bmj open · 10 1. department of internal medicine, soma central hospital, soma city, fukushima, 11...

For peer review only

Impacts of the 2011 Fukushima Nuclear Accident on EMS

times in Soma district: A retrospective observational study

Journal: BMJ Open

Manuscript ID bmjopen-2016-013205

Article Type: Research

Date Submitted by the Author: 28-Jun-2016

Complete List of Authors: Morita, Tomohiro; Soma Central Hospital, Department of Internal Medicine; The University of Tokyo, Institute of Medical Science Tsubokura, Masaharu; Soma Central Hospital, Department of Radiation Protection; The University of Tokyo, Institute of Medical Science Furutani, Tomoyuki; Keio University, Faculty of Policy Management Nomura, Shuhei; Imperial College London, Department of Epidemiology and Biostatistics, School of Public Health Ochi, Sae; Soma Central Hospital, Department of Internal Medicine

Leppold, Claire; Minamisoma Municipal General Hospital, Department of Research Takahara, Kazuhiro; Fire Suppression Division, the Soma Regional Fire Department Shimada, Yuki; Minamisoma Municipal General Hospital, Department of Neurosurgery Fujioka, Sho; Minamisoma Municipal General Hospital, Department of Gastroenterology Kami, Masahiro; The University of Tokyo, Institute of Medical Science Kato, Shigeaki; Research Center, Jyoban Hospital Oikawa, Tomoyoshi; Minamisoma Municipal General Hospital, Department

of Neurosurgery

<b>Primary Subject Heading</b>:

Emergency medicine

Secondary Subject Heading: Global health

Keywords: ACCIDENT & EMERGENCY MEDICINE, PUBLIC HEALTH, Health policy < HEALTH SERVICES ADMINISTRATION & MANAGEMENT, Fukushima Nuclear Accident, Emergency Medical Services, Disaster Medicine

For peer review only - http://bmjopen.bmj.com/site/about/guidelines.xhtml

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Title: Impacts of the 2011 Fukushima Nuclear Accident on EMS times in Soma district: 1

A retrospective observational study 2

3

Authors: Tomohiro Morita [1, 2], Masaharu Tsubokura [2], Tomoyuki Furutani [3], 4

Shuhei Nomura [4], Sae Ochi [1], Claire Leppold [5] Kazuhiro Takahara [6], Yuki 5

Shimada [7], Sho Fujioka [8], Masahiro Kami [2], Shigeaki Kato [9], Tomoyoshi 6

Oikawa [7] 7

8

Affiliations: 9

1. Department of Internal Medicine, Soma Central Hospital, Soma City, Fukushima, 10

Japan. 11

2. Division of Social Communication System for Advanced Clinical Research, 12

Institute of Medical Science, The University of Tokyo, Minato-ku, Tokyo, Japan. 13

3. Faculty of Policy Management, Keio University, Fujisawa, Kanagawa, Japan. 14

4. Department of Epidemiology and Biostatistics, School of Public Health, Imperial 15

College London, Norfolk Place, London, United Kingdom. 16

5. Department of Research, Minamisoma Municipal General Hospital, Minamisoma 17

City, Fukushima, Japan 18

6. Fire Suppression Division, the Soma Regional Fire Department, Minamisoma City, 19

Fukushima, Japan. 20

7. Department of Neurosurgery, Minamisoma Municipal General Hospital, 21

Minamisoma City, Fukushima, Japan. 22

8. Department of Gastroenterology, Minamisoma Municipal General Hospital, 23


9. Department of Radiation Protection, Soma Central Hospital, Soma City, Fukushima, 25

Japan. 26

27

Keywords: ACCIDENT & EMERGENCY MEDICINE, PUBLIC HEALTH, Health 28

policy, Fukushima Nuclear Accident, Emergency Medical Services, Disaster Medicine 29

Corresponding author: 30

Tomohiro Morita 31

Soma Central Hospital 32

3-5-18, Okinouchi, Soma City, Fukushima 33

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976-0016 34

E-mail: [email protected] 35

Tel +81-90-8212-1356 36

Fax +81-244-35-4234 37

38

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Abstract 39

Objective 40

To assess the influence of the 3.11 triple disaster (earthquake, tsunami, and nuclear 41

accident) on the emergency medical service (EMS) system in Fukushima. 42

Methods 43

Total EMS time (from EMS call to arrival at a hospital) was assessed in the EMS 44

system of Soma district, located 10-40km north of the nuclear plant, from March 11 to 45

December 31, 2011. We defined the affected period as when total EMS time was 46

significantly extended after the disasters compared with the historical control data from 47

January 1, 2009 to March 10, 2011. To identify the risk factor of extension of total EMS 48

time after the disasters, we investigated trends in three time segments of total EMS 49

time; response time, defined as time from an EMS call to arrival at the location, 50

on-scene time, defined as time from arrival at the location to departure, and transport 51

time, defined as time from departure from the location to arrival at a hospital. 52

Results 53

The affected period was defined as week 0 to week 11. Median total EMS time in the 54

affected period was 36 (IQR 27-52) minutes while that in the pre-disaster control period 55

was 31 (IQR 24-40) minutes. The percentage of transports exceeding 60 minutes in total 56

EMS time increased from 8.2% (584/7087) in the control period to 22.2% (151/679) in 57

the affected period. Among the three time segments, there was the most change in 58

transport time (SMD: 0.41 vs 0.13-0.17). 59

Conclusion 60

EMS transport was significantly delayed for approximately three months, from week 1 61

to 11 after the 3.11 triple disaster. This delay may be attributed to malfunctioning 62

emergency hospitals after the triple disaster. 63

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Strengths and limitations of this study 64

This is the first study to evaluate the influence of the 3.11 triple disaster (earthquake, 65

tsunami, and nuclear accident) on the Emergency Medical Service (EMS) system in 66

Fukushima. 67

This study suggests that delays in EMS transports after nuclear disasters may be 68

attributed to malfunctioning emergency hospital systems, while EMS systems 69

themselves can be functionally maintained. 70

This study is limited in that the EMS database lacked information concerning vital signs, 71

mental status, mortality or outcome, the severity of patient status or the outcome of 72

EMS transport could not be assessed. 73

Further, there may be a small scope for generalisability of these findings, as this study 74

was focused on a rare and complex disaster (earthquake, tsunami and nuclear accident). 75

76

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INTRODUCTION 77

Establishment and maintenance of emergency medical services (EMS), including rapid 78

transport, is crucial for timely care and a rapid diagnosis. Timely care has been 79

demonstrated to improve outcomes especially in time-sensitive diseases including 80

cardiopulmonary arrest (CPA), ST-elevated myocardial infarction, major trauma, and 81

stroke.1-4 Adequate numbers of EMS transport vehicles and personnel, and capacity of 82

emergency departments (EDs) to accept EMS patients are indispensable for effective 83

EMS systems. Further, functionality of EMS systems appears to largely depend on a 84

proportionate number of calls (demand) and ability to respond (supply). 85

EMS systems malfunction upon unusual circumstances including a large-scale traffic 86

accidents, and natural and man-made disasters.5-7 Following disasters, there is often a 87

significant increase in the number of people sustaining serious injuries, which can 88

subsequently result in an increased demand for EMS. Yet, at the same time as demand 89

for care increases, rapid transport may be interrupted with impassable roads or 90

malfunctioned hospitals due to the damage of disasters.8 In a worst-case scenarios, 91

hospitals may completely suspend their entire ED service after large disasters.9 In these 92

situations, EMS may be forced to take responsibility for triage and initial care of 93

casualties, whether hospitals are functional or not.10-12

94

Nuclear accidents could also be a cause to perturb EMS systems. In previous 95

reports, the number of patients demanding EMS care due to acute radiation exposure 96

has been low because acute radiation exposure is usually limited to nuclear power plant 97

workers who deal with radioactive materials unintentionally or without appropriate 98

knowledge.13-15

However, in the aftermath of nuclear disasters, EMS transport may be 99

impacted by the mass evacuation of medical staff due to fear of radiation exposure. A 100

shortage of medical personnel in emergency care was indeed seen after the nuclear 101

accident at Three Mile Island in 1979, when out of more than 70 doctors, only 6 102

remained in the hospital near the damaged nuclear power plant.16 However, there is 103

currently little information on EMS system maintenance after nuclear disasters. 104

The 2011 accident at the Fukushima Daiichi Nuclear Power Plant in Japan was 105

one of the worst nuclear disasters ever seen in a developed country. Soma district in 106

Fukushima, located from 10 to 40 km north of the plant, was damaged by the triple 107

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disaster (earthquake, tsunami, and nuclear accident), with particularly severe impacts of 108

the nuclear accident. A Nuclear Emergency Situation was declared, and a mandatory 109

evacuation order was issued within a 20 km radius of the plant on March 12, 2011, with 110

a voluntary evacuation zone additionally put into place 20 to 30 km from the power 111

plant (Figure 1A).17 The population of Soma district decreased from nearly 100,000 to 112

40,000 after the evacuation orders.18 Five of eight hospitals with EDs in the district 113

were closed, despite the fact that no hospital facilities were severely damaged by the 114

earthquake or tsunami (Figure 1B). 115

Measurement of elapsed time of EMS transport is a useful way to evaluate the 116

effects of unusual events on the functionality of EMS systems.10 19 20 The purpose of 117

this study is to assess the influence of the 3.11 triple disaster on EMS systems. We 118

investigated total EMS time (time from EMS call to arrival at a hospital) within EMS 119

systems of Soma district for 9 months after the disasters, compared to a pre-disaster 120

control period of 2 years and 3 months. 121

122

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METHODS 123

Design and Setting 124

A retrospective study approved by the Ethics Board of the Minamisoma Municipal 125

General Hospital was undertaken, using cases of patients transported by EMS in Soma 126

district from March 11 to December 31, 2011. To determine the influence of the 127

disasters on the EMS system, EMS data from this period was compared with the 128

historical control data from January 1, 2009 to March 10, 2011 in this district. Soma 129

district constitutes of four municipalities; Iitate Village, Minamisoma City, Soma City, 130

and Shinchi Town, of which populations as of March 1, 2011, were 6,132, 70,752, 131

37,721, and 8,178, respectively. These areas were served by eight hospitals with EDs 132

and five fire stations with EMS depots. Five of the eight hospitals were closed within 133

ten days of the disasters (Figure 1B). However, none of 152 EMS personnel in the fire 134

stations evacuated. The study areas were divided into five regions according to 135

evacuation orders by the government after the nuclear accident; 1) Minamisoma, within 136

20 km of the plant; the area under mandatory evacuation orders after March 12, 2011, 2) 137

Minamisoma, 20 to 30 km from the plant; designated as a voluntary evacuation area 138

from March 15 to April 22, 2011, 3) Minamisoma, further than 30 km from the plant; 139

under no evacuation orders, 4) Iitate; a rural mountain area located 25 to 45 km 140

northwest of the nuclear plant, under mandatory evacuation orders from April 11, 2011, 141

and 5) Soma; an area located more than 40 km to the north from the plant, under no 142

evacuation orders (Figure 1A). 143

144

Data Collection 145

EMS Data from January 1, 2009, to December 31, 2011 was collected from the EMS 146

transport records of the Soma Regional Fire Department. The transport records 147

contained clinical and spatiotemporal data. Clinical data included age, sex, and reasons 148

of EMS call, main complaints or symptoms, temporal data including time of the day, 149

day of the week, and geospatial data at the scene of EMS calls, fire stations, and 150

hospitals. Two independent reviewers (T.M. and K.T.), classified the main complaints 151

into 14 categories as follows: injuries due to the disasters, CPA, injuries unrelated to the 152

disasters, chest pains, disturbance of consciousness (DOC), neurologic symptoms, 153

fevers, shortness of breath (SOB), general weakness, abdominal pains, unspecific pain, 154

overdose/toxic exposure, and self-harm based on past EMS studies.21 22

The total EMS 155

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time was defined from an EMS call to arrival at a hospital, and it was divided in three 156

categories: response time, on-scene time, and transport time.23 The definition of each 157

segment was as follows; a response time was defined as time from an EMS call to 158

arrival of an EMS vehicle at the patient’s location; an on-scene time was defined as time 159

from arrival at the patient’s location to departure from it, and a transport time was 160

defined as time from departure from the patient’s location to arrival at a hospital 161

(excluding time for a triage at the EDs) (Figure 2A). We converted geospatial data into 162

longitude and latitude using Google maps,24 and calculated the actual network distance 163

across roads from the fire station to the patient’s location and from the patient’s location 164

to the hospital with the ArcGIS software.25 165

166

Statistical Analysis 167

This study is comprised of two endpoints. The first is to investigate the extent of 168

disruption on Soma district EMS transport services after the triple disaster as measured 169

by the length of total EMS time. The second is to identify potential determinants 170

contributing to this damage by identifying risk factors for prolonged EMS time during 171

the affected period. 172

173

Primary Analysis 174

The length of total EMS time was examined in every week, from the week of the 175

earthquake (March 11th-17th, 2011) defined as week 0. Data from each week from 176

March 11th, 2011 to December 31th, 2011 was compared with the same week of the 177

control period using a Mann-Whitney U nonparametric test.26 The affected period was 178

defined as the duration during which total median EMS time had been significantly 179

affected by the disasters, starting from week 0 (Figure 2B). In order to assess the 180

influence of the impact of the disasters on these variables, Student's t tests were used to 181

compare the distributions of clinical or spatiotemporal variables of EMS transports 182

between the control and affected period. 183

184

Secondary Analysis 185

A Poisson regression model was used to identify risk factors for prolonged EMS time 186

during the affected period. The total EMS time in minutes was used as the dependent 187

variable. Because of the properties of the Poisson regression, all results represent 188

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multiplicative changes in the total EMS time in minutes for a one-unit change in the 189

covariates. All clinical and spatiotemporal variables were included in the model. 190

P-values of less than 0.05 were considered statistically significant. 191

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RESULTS 192

The initial dataset included 2,648 EMS call records between March 11 and December 193

31 in 2011. Of the 2,648 records, 334 were excluded because of absence of transports to 194

hospitals or transports from hospitals to hospitals, and the remaining 2,314 transports 195

were further studied. After excluding 94 transports of 2,314 with missing or incomplete 196

data of EMS time, the remaining 2,240 transports were used for EMS time analysis. For 197

the control period, of the initial 8,384 records between January 1, 2009 and March 10, 198

2011, 7,107 transports were included in this study. Of the 7,107 transports, 7,087 199

transports with adequate information of EMS time were used as control data for the 200

EMS time analysis. There were no seasonal changes in the number of EMS transports or 201

median total EMS time per week during the control period. 202

Figure 3 shows trends in the number of EMS transports and total EMS time of 203

the 2,314 patients during the study period. A robust peak (n=182) was seen in the 204

number of transported patients per week within the first week after the earthquake 205

occurred on March 11th, 2011, designated as “week 0” in figure 2B and 3. Nearly half 206

of these patients (83/182) were transported to during the first two days. The main 207

reasons for transports in week 0 included injuries related to earthquake or tsunami 208

(n=56), DOC (n=23), injuries unrelated to the disasters (n=14), abdominal pain (n=14), 209

general weakness (n=13) and neurologic symptoms (n=13). After week 0, the number of 210

EMS transports decreased to a similar or lower level compared to the control period. 211

The median total EMS time peaked at 48 minutes in week 2. Statistically 212

extended total EMS time continued up to week 11 compared with the same durations of 213

the control period (Table E1). The affected period was identified from week 0 to 11 and 214

706 of 2,314 transports in this period were further studied. 215

216

Table E1. Comparisons of total EMS time per week.

Week 2011 Control Period 2011 vs Control

n median IQR n median IQR chi sq. P value †

0 162 29 19 125 30 13 0.04 0.83

1 62 41 29 121 31 18 14.04 0.00

2 49 48 36 105 29 14 24.12 0.00

3 32 38 22 122 30 15 5.67 0.02

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4 56 42 31 126 31 20 17.76 0.00

5 34 40 27 126 31 13 15.24 0.00

6 39 36 18 116 27 12 6.33 0.01

7 50 39 26 147 35 21 3.64 0.06

8 41 32 17 129 30 18 3.08 0.08

9 51 42 26 109 32 17 6.53 0.01

10 52 34 13 107 30 15 7.07 0.01

11 51 31 16 119 28 10 4.14 0.04

12 44 32 11 107 30 19 0.70 0.40

13 51 35 14 116 30 13 8.28 0.00

14 43 32 10 113 29 16 2.07 0.15

15 42 29 8 94 30 18 0.30 0.58

16 52 32 13 134 32 21 0.16 0.69

17 54 30 14 133 29 16 0.18 0.67

18 47 33 12 151 33 19 0.24 0.63

19 49 31 13 141 29 18 0.36 0.55

20 53 30 13 132 28 10 1.15 0.28

21 59 31 12 145 31 16 0.28 0.60

22 79 30 9 168 32 18 0.00 0.98

23 49 30 11 127 32 15 0.88 0.35

24 50 34 10 116 30 15 2.39 0.12

25 52 33 16 123 30 14 3.17 0.07

26 39 33 11 127 32 22 0.03 0.85

27 57 33 16 98 30 21 1.49 0.22

28 55 30 19 123 29 14 0.28 0.60

29 55 33 14 116 30 17 2.01 0.16

30 51 32 17 122 33 19 0.07 0.79

31 51 31 15 134 31 18 0.00 0.96

32 52 31 11 112 30 16 0.05 0.83

33 52 31 12 113 29 15 0.26 0.61

34 41 29 10 135 29 16 0.21 0.65

35 52 32 11 129 30 19 1.12 0.29

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36 54 34 13 133 34 21 0.07 0.80

37 57 33 17 141 33 17 0.02 0.89

38 43 33 10 114 33 14 0.03 0.87

39 61 32 15 124 32 16 1.35 0.25

40 52 30 17 128 31 17 0.69 0.41

41 48 33 12 155 31 18 1.27 0.26

† The P value was calculated with the use of a Mann-Whitney U test.

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218

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Table 1: Characteristics of EMS transports in the control and affected period.

Control Period Affected Period P value†

(Control

vs

Affected)

(Week -114 to -1) (Week 0 to 11)

n=7107 n=706

Characteristic No./Week No./Week

All 62.3 58.8 0.41

Patient age, year

0-14 3.5 1.9 0.02 *

15-64 22.4 21.8 0.92

65- 36.4 35.2 0.89

Sex

Male 32.6 27.6 0.30

Female 29.8 31.3 0.82

Time of the day

6 AM-12 PM 20.9 17.8 0.51

12 PM-6 PM 19.2 15.7 0.30

6 PM-12 AM 15.4 15.8 0.64

12 AM-6 AM 6.8 9.6 0.39

Day of the week

Weekday 44.0 40.0 0.64

Weekend 18.3 18.8 0.89

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Scene of EMS call

Soma 19.0 18.1 0.83

Minamisoma 30- km 4.9 4.2 0.34

Minamisoma 20-30 km 22.7 22.8 0.94

Minamisoma -20 km 7.0 1.4 <0.001 ***

Iitate 4.6 5.7 0.13

Others 0.2 0.3 0.33

Reason for EMS call

Disaster-related 0.0 4.8 NA

Abdominal pain 6.0 5.8 0.89

Chest pain 2.9 3.3 0.37

CPA 2.2 1.4 <0.01 **

DOC 10.1 8.6 0.38

Fever 2.2 3.9 <0.01 **

General weakness 3.9 4.0 0.89

Gynecology 0.1 0.2 0.87

Intoxicated 0.7 0.7 0.24

Neurologic symptom 6.8 6.0 0.37

Pain, unspecified 3.1 1.5 <0.001 ***

Self-harm 0.4 0.7 0.12

SOB 4.7 3.3 0.04

Trauma 15.8 8.9 <0.001 ***

Others 0.9 1.3 0.48

Destination area

Soma 20.0 24.1 0.41

Minamisoma 30- km 4.1 3.3 0.65

Minamisoma 20-30 km 30.8 13.6 <0.001 ***

Minamisoma -20 km 1.2 0.3 <0.01 **

Iitate 0.0 0.1 0.58

Outside of study area 5.7 16.7 <0.01 **

EMS, emergency medical services; IQR, interquartile range; CPA,

cardiopulmonary arrest; DOC, disturbance of consciousness; SOB, shortness

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of breath.

† The P values below were calculated with Student's t tests.

* Statistically significant at 0.05 level

** Statistically significant at 0.01 level

220

Table 1 shows the characteristics of EMS transport of the control and affected 221

period. The average number of EMS transports per week was 62 and 59 in the control 222

and affected periods, respectively. The number of transported children aged between 0 223

and 14 per week decreased from 3.5 to 1.9. The number of transports from areas within 224

20 km of the nuclear plant per week additionally decreased, from 7.0 to 1.4. As for 225

destination areas, the number of transports to areas within 20 km (1.2 vs 0.3) and from 226

20 to 30 km of the nuclear plant (30.8 vs 13.6) decreased in the affected period from the 227

control period. Notably, no subject claimed radiation exposure as a reason for EMS 228

calls. 229

Table 2 shows the comparison of elapsed EMS time between the control and 230

affected period. Median lengths of the total EMS times were prolonged to 36 231

(interquartile range (IQR) 27-52) minutes in the affected period from 31 (IQR 24-40) 232

minutes in the control period. As a result, the percentage of transports exceeding 60 233

minutes in total EMS time increased from 8.2% (584/7087) in the control period to 234

22.2% (151/679) in the affected period. Figure 4 shows the density curve for 235

distributions of total EMS time and the three time segments during the control and the 236

affected period. While means and medians of all three time segments had significantly 237

increased during the affected period compared with the control period, the extension of 238

change was the largest in transport time of the three time segments. (Table 2, 239

standardized mean difference: 0.41 vs 0.13-17) 240

241

Table 2: Comparison of EMS time between the control and affected period

Control Period Affected Period P-value

(Control

vs

Affected)

SMD (95% CI) (Week -114 to -1) (Week 0 to 11)

n=7087 n=679

Total EMS time (minutes)

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Median (IQR) 31 (24-40) 36 (27-52) <0.001 †

Mean (SD) 35 (17.4) 43 (2.3) <0.001 ‡ 0.41 (0.40-0.43)

>60 min (%) 584 (8.2) 151 (22.2) <0.001 ¶

Response time (minutes)

Median (IQR) 8 (6-10) 8 (6-11) <0.001 †

Mean (SD) 8.5 (4.6) 9.2 (5.3) <0.001 ‡ 0.17 (0.14-0.20)

On-scene time (minutes)

Median (IQR) 13 (10-18) 15 (11-19) <0.001 †

Mean (SD) 15 (7.4) 16 (8.5) <0.001 ‡ 0.13 (0.10-0.15)

Transport time (minutes)

Median (IQR) 7 (4-14) 10 (5-23) <0.001 †

Mean (SD) 12 (13.2) 18 (19.1) <0.001 ‡ 0.41 (0.39-0.43)

EMS, emergency medical services; SMD, standardized mean difference; IQR, interquartile range;

SD, standard deviation; CPA, cardiopulmonary arrest; DOC, disturbance of consciousness; SOB,

shortness of breath.

† Mann-Whitney's U test

‡ Welch's t test

¶ Chi-square test

242

A multivariate analysis was used to illustrate the patient group with prolonged 243

total EMS time in the control and affected period (Table 3). Total EMS time was 244

associated with the distance from the fire station to the scene of EMS call and the 245

distance from the scene of EMS call to the hospital in the both control and affected 246

period (relative ratio of total EMS time (RR): 1.02 per kilometre for all). In addition, the 247

extension of total EMS time was, in the both control and affected period, associated 248

with EMS transports at night (from 6 PM to 6 AM, RR: 1.06-1.14 and 1.06-1.07) and 249

EMS calls from Iitate, the mountainous area far from emergency hospitals (RR: 1.07 250

and 1.15). Conversely, in the both control and affected periods, reduced total EMS time 251

was associated with EMS transports of children aged 0 to 14 (RR: 0.89 and 0.79), of 252

females (RR: 0.99 and 0.97), from the area within 20 km from the nuclear plant (RR: 253

0.83), and transports due to CPA (RR: 0.89) or due to self-harm (RR: 0.86). Although 254

10 of 14 reasons for EMS calls were associated with the total EMS time in the control 255

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period, this proportion dropped to 5 of 15 in the affected period, with the added 256

category of disaster-related calls. 257

258

Table 3: Multivariate poisson regression model for total EMS time in the control and affected period.

Control Period Affected Period

Estimate 95% CI P value Estimate 95% CI

Constant, minutes 24.0 (23.5-24.4) <0.001 *** 28.6 (27.1-30.1)

Variable RR 95% CI P value RR 95% CI

Age, year

0-14 0.89 (0.88-0.91) <0.001 *** 0.79 (0.72-0.86)

15-64 Reference - Reference

65- 0.98 (0.98-0.99) <0.001 *** 0.98 (0.95-1.01)

Sex

Male Reference - Reference

Female 0.99 (0.98-1.00) <0.01 ** 0.97 (0.94-0.99)

Time of the day

6 AM-12 PM Reference - Reference

12 PM-6 PM 1.01 (1.00-1.02) 0.17 0.96 (0.93-0.99)

6 PM-12 AM 1.06 (1.05-1.07) <0.001 *** 1.07 (1.03-1.11)

12 AM-6 AM 1.14 (1.12-1.15) <0.001 *** 1.06 (1.02-1.11)

Day of the week

Weekday Reference - Reference

Weekend 1.01 (1.00-1.02) <0.01 ** 0.98 (0.95-1.00)

Scene of EMS call

Soma† Reference - Reference

Minamisoma 30- km 0.98 (0.96-1.00) 0.01 * 0.83 (0.79-0.87)

Minamisoma 20-30 km 0.97 (0.96-0.98) <0.001 *** 0.97 (0.94-1.00)

Minamisoma -20 km 1.07 (1.06-1.09) <0.001 *** 0.95 (0.87-1.04)

Iitate 1.07 (1.05-1.09) <0.001 *** 1.15 (1.11-1.20)

Other 1.04 (0.98-1.11) 0.21 1.35 (1.19-1.53)

Reason for EMS call

Disaster-related - - 1.08 (1.01-1.15)

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Abdominal pain Reference - Reference

Chest pain 1.06 (1.04-1.08) <0.001 *** 1.01 (0.95-1.07)

CPA 0.97 (0.94-0.99) <0.01 ** 0.86 (0.79-0.94)

DOC 1.04 (1.03-1.06) <0.001 *** 1.02 (0.97-1.07)

Fever 1.01 (0.98-1.03) 0.61 1.05 (0.99-1.12)

General weakness 1.07 (1.05-1.10) <0.001 *** 1.03 (0.97-1.10)

Gynecology 0.91 (0.83-1.00) 0.05 * 0.89 (0.72-1.10)

Intoxicated 1.13 (1.09-1.18) <0.001 *** 1.31 (1.20-1.44)

Neurologic symptom 1.05 (1.04-1.07) <0.001 *** 1.00 (0.95-1.06)

Pain, unspecified 1.12 (1.10-1.15) <0.001 *** 1.07 (0.98-1.15)

Self-harm 1.15 (1.10-1.21) <0.001 *** 0.86 (0.76-0.97)

SOB 1 (0.98-1.02) 0.74 1.02 (0.96-1.09)

Trauma 1.08 (1.06-1.10) <0.001 *** 1.02 (0.97-1.07)

Other 1 (0.96-1.03) 0.90 1.11 (1.02-1.20)

Distance (km)

from FS to scene of call 1.02 (1.02-1.02) <0.001 *** 1.02 (1.02-1.02)

from scene of call to hospital 1.02 (1.02-1.02) <0.001 *** 1.02 (1.02-1.02)

EMS, emergency medical services; RR, relative ratio; CI, confidence interval; FS, fire station.

*Statistically significant at 0.05 level

**Statistically significant at 0.01 level

***Statistically significant at 0.001 level

259

260

261

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DISCUSSION 262

This study is the first study to assess an EMS system in Fukushima after the triple 263

disaster. The results of this study indicate that the median total EMS time was prolonged 264

from week 1 to 11 after the triple disaster and recovered to the pre-disaster control level 265

from week 12. 266

It is possible that the extension of EMS time from the week 1 to 11 was related 267

to prolonged transport distance from the scene of EMS calls to the hospitals. This 268

hypothesis is supported by several findings. First, results of the multivariable model 269

indicate that the effect of the distance for EMS transport per kilometre on total EMS 270

time was similar in the affected period to that in the control period (RR: 1.02 vs 1.02). 271

Second, the largest change of the three time segments was seen in transport times (Table 272

2), suggesting that the extension of EMS time can be mainly attributed to prolonged 273

transport distance from the scene to the hospitals. Third, the number of the transports 274

per week to hospitals outside Soma district significantly increased, from 5.7 (9.1%) to 275

16.7 (28.4%) while those to hospitals within 30 km from the nuclear plant in 276

Minamisoma City significantly decreased (32.0 vs 13.9, Table 1). 277

As to the reason for distance prolongation, we presume that hospital closures 278

had been a main cause as the affected period was chronologically consistent with the 279

duration of hospital closures, from the timing of the closings of five hospitals in weeks 280

0 and 1 (Figure 1B) until the timing of the reopening of three hospitals in weeks 5, 8, 281

and 14 (Figure E1). There were two kinds of hospital closures in Soma district. First, 282

one of the five hospital was located in the mandatory evacuation area, and forced to 283

evacuate on March 12, 2011. Second, the other four closed hospitals were located in the 284

voluntary evacuation area and it is true that multiple reasons could have led to their 285

closure. However, our discussion with hospital administrators suggest that the main 286

cause of hospital closures in the study area was due to a lack of human resources and 287

material resources including food and drugs in these hospitals. For instance, 288

Minamisoma Municipal General Hospital, with the most bed in Soma district, has 289

closed after 71 of the 239 staff voluntarily evacuated following the nuclear accident 290

without mandatory evacuation orders.27 Voluntary evacuation of hospital staff after a 291

disaster was similarly reported after the Three Mile Island accident or Chi-Chi 292

earthquake.16 28

In all, four emergency hospitals located in the voluntary evacuation area 293

and one in the mandatory evacuation area were closed by week 1 (Figure 1B). As the 294

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hospitals with EDs in Soma district did not suffer from physical damage to the hospital 295

buildings, we presume that the hospital closures were related to staffing issues rather 296

than damage to physical infrastructure. It is of note that EMS staff had continued 297

working even in the evacuation areas, which may highlight a different response to a 298

disaster between hospital and EMS staff. Past studies have indicated that EMS staff may 299

be more likely than other medical staff to take risks for people in need.29 30

It can be 300

hypothesized that hospitals could be more vulnerable to staff shortages than EMS after 301

disasters. 302

Interestingly, this study suggests that the extension of EMS times was not 303

limited to evacuation areas. In the affected period, total EMS time was prolonged in all 304

area of Soma district, not only the 30 km from the nuclear plant where hospital closures 305

occurred. The multivariate analysis suggests that the influence of the call location on 306

total EMS time were similar in the affected period to that in the control period, which 307

indicates that EMS transports from within 30 km from the plant were not delayed more 308

than other areas (Table 3). 309

It is worth nothing that mass casualties from the disaster did not disrupt the EMS 310

system in Soma district in this study. The number of EMS transports was 2.9 higher 311

than that before the disasters in week 0. Approximately one third of these patients were 312

transported due to injuries from the earthquake and tsunami (57/182) while no patient 313

was transported due to acute radiation exposure. In spite of the increased number of 314

transports, total EMS time was not prolonged in week 0. In past disasters, it has been 315

reported that mass casualties can extend total EMS time.31 32 This suggests that the 316

number of casualties of the triple disaster did not overcome the capacity of the EMS 317

systems in Soma district. 318

319

LIMITATIONS 320

Because the EMS database lacks information concerning vital signs, mental 321

status, mortality or outcome, the severity of patient status or the outcome of EMS 322

transport could not be assessed. In addition, due to lack of data on the population of 323

Soma district from March to May, 2011, the relationship between EMS transports and 324

population immediately after the disasters could not be evaluated. 325

This study was unable to assess transports within a 10 km radius of the nuclear 326

plant because Soma Regional Fire Department did not cover this area. As a result, the 327

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areas investigated in this study were restricted to places with relatively low radiation 328

levels, and the results of this study may not be applicable to areas significantly 329

contaminated in radiation-release accidents. 330

331

CONCLUSION 332

This study shows that the elapsed time in EMS transport was significantly 333

prolonged from week 1 to 11. This delay could be mainly attributed to malfunctioning 334

emergency hospital systems after the nuclear disaster. 335

336

Acknowledgements 337

We are grateful to all of the staff in emergency departments or hospitals in Soma district 338

who have managed patients in the aftermath of the disasters. 339

340

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LEGEND 445

Figure 1A: Five regions of the study area according to evacuation orders by the 446

government after the nuclear accident; 1) Minamisoma, within 20 km of the plant; the 447

area under mandatory evacuation orders after March 12, 2011, 2) Minamisoma, 20 to 30 448

km from the plant; designated as a voluntary evacuation area from March 15 to April 22, 449

2011, 3) Minamisoma, further than 30 km from the plant; under no evacuation orders, 450

4) Iitate; a rural mountain area located 25 to 45 km northwest of the nuclear plant, under 451

mandatory evacuation orders after April 11, 2011, and 5) Soma; an area located more 452

than 40 km to the north from the plant, under no evacuation orders. 453

454

Figure 1B: The periods of hospital closures. Each letter corresponds to the hospital ID 455

in Figure 1A. 456

457

Figure 2A: Definition of three time segments of total EMS time. 458

459

Figure 2B: Description of the time course of study period: the duration during which 460

total median EMS time had been significantly affected by the disasters, starting from 461

week 0, March 11th to 17th in 2011. 462

463

Figure 3: Trends in the number of EMS transports and median total EMS time. The 464

week of the earthquake (March 11-17 in 2011) is defined as week 0. 465

466

Figure 4: The dense curves of total EMS time and three time segments; response time, 467

on-scene time, and transport time during the control and affected period. 468

469

Table 1: Characteristics of EMS transports of the control and affected period. 470

Table 2: Comparison of EMS time between the control and affected period 471

Table 3: Multivariable poisson regression model for total EMS time in the control and 472

affected period. 473

474

Web Appendices 475

Figure E1: The relationship of total EMS time and the timing of closing and reopening 476

of hospitals. Each letter corresponds to the hospital ID in figure 1. 477

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Table E1: Comparisons of total EMS time per week. 478

479

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Contributorship statement: TM, MT, MK, and TO developed the concept and 480

designed the study. SO, KT and SK supervised the data collection. TM, MT, YS, SF and 481

CL collected and managed the data, including quality control. SN and TF provided 482

statistical advice on study design and analysed the data. TM drafted the manuscript, and 483

all authors contributed substantially to its revision. TM takes responsibility for the paper 484

as a whole. 485

Funding statement: There is no funding to report for this submission 486

Competing interests: None declared. 487

Data sharing statement: No additional data are available. 488

489

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Five regions of the study area according to evacuation orders by the government after the nuclear accident; 1) Minamisoma, within 20 km of the plant; the area under mandatory evacuation orders after March 12, 2011, 2) Minamisoma, 20 to 30 km from the plant; designated as a voluntary evacuation area from March

15 to April 22, 2011, 3) Minamisoma, further than 30 km from the plant; under no evacuation orders, 4) Iitate; a rural mountain area located 25 to 45 km northwest of the nuclear plant, under mandatory

evacuation orders after April 11, 2011, and 5) Soma; an area located more than 40 km to the north from the plant, under no evacuation orders.

Figure 1A 254x190mm (96 x 96 DPI)

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The periods of hospital closures. Each letter corresponds to the hospital ID in Figure 1A. Figure 1B

338x190mm (96 x 96 DPI)

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A: Definition of three time segments of total EMS time. B: Description of the time course of study period: the duration during which total median EMS time had been significantly affected by the disasters, starting

from week 0, March 11th to 17th in 2011. Figure 2

338x190mm (96 x 96 DPI)

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Trends in the number of EMS transports and median total EMS time. The week of the earthquake (March 11-17 in 2011) is defined as week 0.

Figure 3 271x198mm (96 x 96 DPI)

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The dense curves of total EMS time and three time segments; response time, on-scene time, and transport time during the control and affected period.

Figure 4

219x278mm (300 x 300 DPI)

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338x190mm (96 x 96 DPI)

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Impacts of the 2011 Fukushima Nuclear Accident on Emergency Medical Service Times in Soma District, Japan: A

retrospective observational study.

Journal: BMJ Open

Manuscript ID bmjopen-2016-013205.R1

Article Type: Research

Date Submitted by the Author: 06-Sep-2016

Complete List of Authors: Morita, Tomohiro; Soma Central Hospital, Department of Internal Medicine; The University of Tokyo, Institute of Medical Science Tsubokura, Masaharu; Soma Central Hospital, Department of Radiation

Protection; The University of Tokyo, Institute of Medical Science Furutani, Tomoyuki; Keio University, Faculty of Policy Management Nomura, Shuhei; Imperial College London, Department of Epidemiology and Biostatistics, School of Public Health Ochi, Sae; Soma Central Hospital, Department of Internal Medicine Leppold, Claire; Minamisoma Municipal General Hospital, Department of Research Takahara, Kazuhiro; Fire Suppression Division, the Soma Regional Fire Department Shimada, Yuki; Minamisoma Municipal General Hospital, Department of Neurosurgery Fujioka, Sho; Minamisoma Municipal General Hospital, Department of

Gastroenterology Kami, Masahiro; The University of Tokyo, Institute of Medical Science Kato, Shigeaki; Research Center, Jyoban Hospital Oikawa, Tomoyoshi; Minamisoma Municipal General Hospital, Department of Neurosurgery

<b>Primary Subject Heading</b>:

Emergency medicine

Secondary Subject Heading: Global health

Keywords: ACCIDENT & EMERGENCY MEDICINE, PUBLIC HEALTH, Health policy < HEALTH SERVICES ADMINISTRATION & MANAGEMENT, Fukushima Nuclear Accident, Emergency Medical Services, Disaster Medicine


BMJ Open on S

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Title: Impacts of the 2011 Fukushima Nuclear Accident on Emergency Medical Service 1

Times in Soma District, Japan: A retrospective observational study. 2

3

Authors: Tomohiro Morita [1, 2], Masaharu Tsubokura [2], Tomoyuki Furutani [3], 4

Shuhei Nomura [4], Sae Ochi [1], Claire Leppold [5] Kazuhiro Takahara [6], Yuki 5

Shimada [7], Sho Fujioka [8], Masahiro Kami [2], Shigeaki Kato [9], Tomoyoshi 6

Oikawa [7] 7

8

Affiliations: 9

1. Department of Internal Medicine, Soma Central Hospital, Soma City, Fukushima, 10

Japan. 11

2. Division of Social Communication System for Advanced Clinical Research, 12

Institute of Medical Science, The University of Tokyo, Minato-ku, Tokyo, Japan. 13

3. Faculty of Policy Management, Keio University, Fujisawa, Kanagawa, Japan. 14

4. Department of Epidemiology and Biostatistics, School of Public Health, Imperial 15

College London, Norfolk Place, London, United Kingdom. 16

5. Department of Research, Minamisoma Municipal General Hospital, Minamisoma 17

City, Fukushima, Japan 18

6. Fire Suppression Division, the Soma Regional Fire Department, Minamisoma City, 19

Fukushima, Japan. 20

7. Department of Neurosurgery, Minamisoma Municipal General Hospital, 21


8. Department of Gastroenterology, Minamisoma Municipal General Hospital, 23


9. Department of Radiation Protection, Soma Central Hospital, Soma City, Fukushima, 25

Japan. 26

27

Keywords: ACCIDENT & EMERGENCY MEDICINE, PUBLIC HEALTH, Health 28

policy, Fukushima Nuclear Accident, Emergency Medical Services, Disaster Medicine 29

Corresponding author: 30

Tomohiro Morita 31

Soma Central Hospital 32

3-5-18, Okinouchi, Soma City, Fukushima, 976-0016 33

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E-mail: [email protected] 34

Tel +81-90-8212-1356 35

Fax +81-244-35-4234 36

37

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Abstract 38

Objective 39

To assess the influence of the 3.11 triple disaster (earthquake, tsunami, and nuclear 40

accident) on the emergency medical service (EMS) system in Fukushima. 41

Methods 42

Total EMS time (from EMS call to arrival at a hospital) was assessed in the EMS 43

system of Soma district, located 10-40km north of the nuclear plant, from March 11 to 44

December 31, 2011. We defined the affected period as when total EMS time was 45

significantly extended after the disasters compared with the historical control data from 46

January 1, 2009 to March 10, 2011. To identify risk factors associated with the 47

extension of total EMS time after the disasters, we investigated trends in three time 48

segments of total EMS time; response time, defined as time from an EMS call to arrival 49

at the location, on-scene time, defined as time from arrival at the location to departure, 50

and transport time, defined as time from departure from the location to arrival at a 51

hospital. 52

Results 53

For the affected period from week 0 to week 11, the median total EMS time was 36 54

(IQR 27-52) minutes while that in the pre-disaster control period was 31 (IQR 24-40) 55

minutes. The percentage of transports exceeding 60 minutes in total EMS time 56

increased from 8.2% (584/7087) in the control period to 22.2% (151/679) in the affected 57

period. Among the three time segments, there was the most change in transport time 58

(SMD: 0.41 vs 0.13-0.17). 59

Conclusion 60

EMS transport was significantly delayed for approximately three months, from week 1 61

to 11 after the 3.11 triple disaster. This delay may be attributed to malfunctioning 62

emergency hospitals after the triple disaster. 63

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Strengths and limitations of this study 64

• This is the first study to evaluate the influence of the 3.11 triple disaster 65

(earthquake, tsunami, and nuclear accident) on the Emergency Medical Service 66

(EMS) system in Fukushima. 67

• This study suggests that delays in EMS transports after nuclear disasters may be 68

attributed to closures of hospitals providing emergency care, while EMS systems 69

themselves can be functionally maintained. 70

• This study is limited in that the EMS database lacked information concerning 71

vital signs, mental status, mortality or outcome, the severity of patient status or 72

the outcome of EMS transport could not be assessed. 73

• Further, there may be a small scope for generalisability of these findings, as this 74

study was focused on a rare and complex disaster (earthquake, tsunami and 75

nuclear accident). 76

77

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INTRODUCTION 78

Establishment and maintenance of emergency medical services (EMS), including rapid 79

transport, is crucial for timely care and a rapid diagnosis. Timely care has been 80

demonstrated to improve outcomes especially in time-sensitive diseases including 81

cardiopulmonary arrest (CPA), ST-elevated myocardial infarction, major trauma, and 82

stroke.1-4 Adequate numbers of EMS transport vehicles and personnel, and capacity of 83

emergency departments (EDs) to accept EMS patients are indispensable for effective 84

EMS systems. Further, functionality of EMS systems appears to largely depend on a 85

proportionate number of calls (demand) and ability to respond (supply). 86

EMS systems are disrupted upon unusual circumstances including a large-scale traffic 87

accidents, and natural and man-made disasters.5-7 Following disasters, there is often a 88

significant increase in the number of people sustaining serious injuries, which can 89

subsequently result in an increased demand for EMS. Yet, at the same time as demand 90

for care increases, rapid transport may be interrupted with roads or hospitals closed or 91

damaged by disasters.8 In a worst-case scenarios, hospitals may completely suspend 92

their entire ED service after large disasters.9 In these situations, EMS may be forced to 93

take responsibility for triage and initial care of casualties, whether hospitals are 94

functional or not.10-12

95

Nuclear accidents could also be a cause to perturb EMS systems. In previous 96

reports, the number of patients demanding EMS care due to acute radiation exposure 97

has been low because acute radiation exposure is usually limited to nuclear power plant 98

workers who deal with radioactive materials unintentionally or without appropriate 99

knowledge.13-15

However, in the aftermath of nuclear disasters, EMS transport may be 100

impacted by the mass evacuation of medical staff to prevent radiation exposure. A 101

shortage of medical personnel in emergency care was indeed seen after the nuclear 102

accident at Three Mile Island in 1979, when out of more than 70 doctors, only 6 103

remained in the hospital near the damaged nuclear power plant.16 However, there is 104

currently little information on the functioning of EMS systems after nuclear disasters. 105

The 2011 accident at the Fukushima Daiichi Nuclear Power Plant in Japan was 106

one of the worst nuclear disasters ever seen in a developed country. Soma district in 107

Fukushima, located from 10 to 40 km north of the plant, was damaged by the triple 108

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disaster (earthquake, tsunami, and nuclear accident), with particularly severe impacts of 109

the nuclear accident. A Nuclear Emergency Situation was declared, and a mandatory 110

evacuation order was issued within the 20 km radius of the plant on March 12, 2011, 111

with a voluntary evacuation zone additionally put into place 20 to 30 km from the 112

power plant (Figure 1A).17 The population of Soma district decreased from nearly 113

100,000 to 40,000 after the evacuation orders.18 Though no hospital facilities were 114

severely damaged by the earthquake or tsunami, five of the eight hospitals with EDs in 115

the district were closed (Figure 1B). 116

Measurement of elapsed time of EMS transport is a useful way to evaluate the 117

effects of unusual events on the functionality of EMS systems.10 19 20 The purpose of 118

this study is to assess the influence of the 3.11 triple disaster on EMS systems. We 119

investigated total EMS time (time from EMS call to arrival at a hospital) within EMS 120

systems of Soma district for 9 months after the disasters, compared to a pre-disaster 121

control period of 2 years and 3 months. 122

123

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METHODS 124

Design and Setting 125

A retrospective study approved by the Ethics Board of the Minamisoma Municipal 126

General Hospital was undertaken, using cases of patients transported by EMS in Soma 127

district from March 11 to December 31, 2011. To determine the influence of the 128

disasters on the EMS system, EMS data from this period was compared with the 129

historical control data from January 1, 2009 to March 10, 2011 in this district. Soma 130

district constitutes of four municipalities; Iitate Village, Minamisoma City, Soma City, 131

and Shinchi Town, of which populations as of March 1, 2011, were 6,132, 70,752, 132

37,721, and 8,178, respectively. These areas were served by eight hospitals with EDs 133

and five fire stations with EMS depots. Five of the eight hospitals were closed within 134

ten days of the disasters (Figure 1B). However, none of 152 EMS personnel in the fire 135

stations evacuated. The study areas were divided into five regions according to 136

evacuation orders by the government after the nuclear accident; 1) Minamisoma, within 137

20 km of the plant; the area under mandatory evacuation orders after March 12, 2011, 2) 138

Minamisoma, 20 to 30 km from the plant; designated as a voluntary evacuation area 139

from March 15 to April 22, 2011, 3) Minamisoma, further than 30 km from the plant; 140

under no evacuation orders, 4) Iitate; a rural mountain area located 25 to 45 km 141

northwest of the nuclear plant, under mandatory evacuation orders from April 11, 2011, 142

and 5) Soma; an area located more than 40 km to the north from the plant, under no 143

evacuation orders (Figure 1A). 144

145

Data Collection 146

EMS Data from January 1, 2009, to December 31, 2011 was collected from the EMS 147

transport records of the Soma Regional Fire Department. The transport records 148

contained clinical and spatiotemporal data. Clinical data included age, sex, and reasons 149

of EMS call, main complaints or symptoms, temporal data including time of the day, 150

day of the week, and geospatial data at the scene of EMS calls, fire stations, and 151

hospitals. Two independent reviewers (T.M. and M.T.), classified the main complaints 152

into 14 categories as follows: injuries due to the disasters, CPA, injuries unrelated to the 153

disasters, chest pains, disturbance of consciousness (DOC), neurologic symptoms, 154

fevers, shortness of breath (SOB), general weakness, abdominal pains, unspecific pain, 155

overdose/toxic exposure, and self-harm based on past EMS studies.21 22

The total EMS 156

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time was defined from an EMS call to arrival at a hospital, and it was divided in three 157

categories: response time, on-scene time, and transport time.23 The definition of each 158

segment was as follows; a response time was defined as time from an EMS call to 159

arrival of an EMS vehicle at the patient’s location; an on-scene time was defined as time 160

from arrival at the patient’s location to departure from it, and a transport time was 161

defined as time from departure from the patient’s location to arrival at a hospital 162

(excluding time for a triage at the EDs) (Figure 2A). We converted geospatial data into 163

longitude and latitude using Google maps,24 and calculated the actual network distance 164

across roads from the fire station to the patient’s location and from the patient’s location 165

to the hospital with the ArcGIS software.25 166

167

Statistical Analysis 168

This study is comprised of two endpoints. The first is to investigate the extent of 169

disruption on Soma district EMS transport services after the triple disaster as measured 170

by the length of total EMS time. The second is to identify potential determinants 171

contributing to this damage by identifying risk factors for prolonged EMS time during 172

the affected period. 173

174

Primary Analysis 175

The length of total EMS time was examined in every week, from the week of the 176

earthquake (March 11th-17th, 2011) defined as week 0. Data from each week from 177

March 11th, 2011 to December 31th, 2011 was compared with the same week of the 178

control period using a Mann-Whitney U nonparametric test.26 The affected period was 179

defined as the duration during which total median EMS time had been significantly 180

affected by the disasters, starting from week 0 (Figure 2B). In order to assess the 181

influence of the impact of the disasters on these variables, Student's t tests were used to 182

compare the distributions of clinical or spatiotemporal variables of EMS transports 183

between the control and affected period. 184

185

Secondary Analysis 186

A Poisson regression model was used to identify risk factors for prolonged EMS time 187

during the affected period. The total EMS time in minutes was used as the dependent 188

variable. Because of the properties of the Poisson regression, all results represent 189

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multiplicative changes in the total EMS time in minutes for a one-unit change in the 190

covariates. All clinical and spatiotemporal variables were included in the model. P 191

values of less than 0.05 were considered statistically significant. 192

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RESULTS 193

The initial dataset included 2,648 EMS call records between March 11 and December 194

31 in 2011. Of the 2,648 records, 334 were excluded because they were not transports to 195

hospitals or they were transports between hospitals, and the remaining 2,314 transports 196

were studied. After excluding 94 transports of 2,314 with missing or incomplete data of 197

EMS time, the remaining 2,240 transports were used for EMS time analysis. For the 198

control period, of the initial 8,384 records between January 1, 2009 and March 10, 2011, 199

7,107 transports were included in this study. Of the 7,107 transports, 7,087 transports 200

with adequate information of EMS time were used as control data for the EMS time 201

analysis. There were no seasonal changes in the number of EMS transports or in the 202

length of total EMS times per week during the control period (P = 0.48 and 0.06 by 203

Kruskal-Wallis test, respectively). 204

Figure 3 shows trends in the number of EMS transports and total EMS time of 205

the 2,314 patients during the study period. A robust peak (n=182) was seen in the 206

number of transported patients per week within the first week after the earthquake 207

occurred on March 11th, 2011, designated as “week 0” in figure 2B and 3. Nearly half 208

of these patients (83/182) were transported to during the first two days. The main 209

reasons for transports in week 0 included injuries related to earthquake or tsunami 210

(n=56), DOC (n=23), injuries unrelated to the disasters (n=14), abdominal pain (n=14), 211

general weakness (n=13) and neurologic symptoms (n=13). After week 0, the number of 212

EMS transports decreased to a similar or lower level compared to the control period. 213

The median total EMS time peaked at 48 minutes in week 2. Statistically 214

extended total EMS time continued up to week 11 compared with the same durations of 215

the control period (Table E1). The affected period was identified from week 0 to 11 and 216

706 of 2,314 transports in this period were further studied. 217

218

Table 1: Characteristics of EMS transports in the control and

affected period.

Control Period Affected Period P value†

(Control vs

Affected)

(Week -114 to -1) (Week 0 to 11)

n=7107 n=706

Characteristic No./Week No./Week

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All 62.3 58.8 0.41

Patient age,

year

0-14 3.5 1.9 0.02 *

15-64 22.4 21.8 0.92

65- 36.4 35.2 0.89

Sex

Male 32.6 27.6 0.30

Female 29.8 31.3 0.82

Time of the day

6 AM-12 PM 20.9 17.8 0.51

12 PM-6 PM 19.2 15.7 0.30

6 PM-12 AM 15.4 15.8 0.64

12 AM-6 AM 6.8 9.6 0.39

Day of the week

Weekday 44.0 40.0 0.64

Weekend 18.3 18.8 0.89

Scene of EMS

call

Soma 19.0 18.1 0.83

Minamisoma 30-

km 4.9 4.2 0.34

Minamisoma

20-30 km 22.7 22.8 0.94

Minamisoma -20

km 7.0 1.4 <0.001 ***

Iitate 4.6 5.7 0.13

Others 0.2 0.3 0.33

Reason for

EMS call

Disaster-related 0.0 4.8 NA

Abdominal pain 6.0 5.8 0.89

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Chest pain 2.9 3.3 0.37

CPA 2.2 1.4 <0.01 **

DOC 10.1 8.6 0.38

Fever 2.2 3.9 <0.01 **

General

weakness 3.9 4.0 0.89

Gynecology 0.1 0.2 0.87

Intoxicated 0.7 0.7 0.24

Neurologic

symptom 6.8 6.0 0.37

Pain,

unspecified 3.1 1.5 <0.001 ***

Self-harm 0.4 0.7 0.12

SOB 4.7 3.3 0.04

Trauma 15.8 8.9 <0.001 ***

Others 0.9 1.3 0.48

Destination

area

Soma 20.0 24.1 0.41

Minamisoma 30-

km 4.1 3.3 0.65

Minamisoma

20-30 km 30.8 13.6 <0.001 ***

Minamisoma -20

km 1.2 0.3 <0.01 **

Iitate 0.0 0.1 0.58

Outside of study

area 5.7 16.7 <0.01 **

EMS, emergency medical services; IQR, interquartile range; CPA,

cardiopulmonary arrest; DOC, disturbance of consciousness; SOB, shortness of

breath.

† The P values below were calculated with Student's t tests.

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* Statistically significant at 0.05 level

** Statistically significant at 0.01 level

219

Table 1 shows the characteristics of EMS transport of the control and affected 220

period. The average number of EMS transports per week was 62 and 59 in the control 221

and affected periods, respectively. The number of transported children aged between 0 222

and 14 per week decreased from 3.5 to 1.9. The number of transports from areas within 223

20 km of the nuclear plant per week additionally decreased, from 7.0 to 1.4. As for 224

destination areas, the number of transports to areas within 20 km (1.2 vs 0.3) and from 225

20 to 30 km of the nuclear plant (30.8 vs 13.6) decreased in the affected period from the 226

control period. Notably, no subject claimed radiation exposure as a reason for EMS 227

calls. 228

Table 2 shows the comparison of elapsed EMS time between the control and 229

affected period. Median lengths of the total EMS times were prolonged to 36 230

(interquartile range (IQR) 27-52) minutes in the affected period from 31 (IQR 24-40) 231

minutes in the control period. As a result, the percentage of transports exceeding 60 232

minutes in total EMS time increased from 8.2% (584/7087) in the control period to 233

22.2% (151/679) in the affected period. Figure 4 shows the density curve for 234

distributions of total EMS time and the three time segments during the control and the 235

affected period. While means and medians of all three time segments had significantly 236

increased during the affected period compared with the control period, the extension of 237

change was the largest in transport time of the three time segments. (Table 2, 238

standardized mean difference: 0.41 vs 0.13-17) 239

240

Table 2: Comparison of EMS time between the control and

affected period

Control

Period

Affected

Period

P-value

(Contro

l vs

Affecte

d)

SMD (95%

CI) (Week -114 to

-1)

(Week 0 to

11)

n=7087 n=679

Total EMS time

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(minutes)

Median (IQR) 31 (24-40) 36 (27-52) <0.00

1 †

Mean (SD) 35 (17.4) 43 (2.3) <0.00

1 ‡

0.41

(0.40-0.43)

>60 min (%) 584 (8.2) 151 (22.2) <0.00

1 ¶

Response time

(minutes)

Median (IQR) 8 (6-10) 8 (6-11) <0.00

1 †

Mean (SD) 8.5 (4.6) 9.2 (5.3) <0.00

1 ‡

0.17

(0.14-0.20)

On-scene time

(minutes)

Median (IQR) 13 (10-18) 15 (11-19) <0.00

1 †

Mean (SD) 15 (7.4) 16 (8.5) <0.00

1 ‡

0.13

(0.10-0.15)

Transport time

(minutes)

Median (IQR) 7 (4-14) 10 (5-23) <0.00

1 †

Mean (SD) 12 (13.2) 18 (19.1) <0.00

1 ‡

0.41

(0.39-0.43)

EMS, emergency medical services; SMD, standardized mean difference; IQR,

interquartile range; SD, standard deviation; CPA, cardiopulmonary arrest; DOC,

disturbance of consciousness; SOB, shortness of breath.

† Mann-Whitney's U test

‡ Welch's t test

¶ Chi-square test

241

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A multivariate analysis was used to illustrate the patient group with prolonged 242

total EMS time in the control and affected period (Table 3). Total EMS time was 243

associated with the distance from the fire station to the scene of EMS call and the 244

distance from the scene of EMS call to the hospital in the both control and affected 245

period (relative ratio of total EMS time (RR): 1.02 per kilometre for all). In addition, the 246

extension of total EMS time was, in the both control and affected period, associated 247

with EMS transports at night (from 6 PM to 6 AM, RR: 1.06-1.14 and 1.06-1.07) and 248

EMS calls from Iitate, the mountainous area far from emergency hospitals (RR: 1.07 249

and 1.15). Conversely, in the both control and affected periods, reduced total EMS time 250

was associated with EMS transports of children aged 0 to 14 (RR: 0.89 and 0.79), of 251

females (RR: 0.99 and 0.97), from the area within 20 km from the nuclear plant (RR: 252

0.83), and transports due to CPA (RR: 0.89) or due to self-harm (RR: 0.86). Although 253

10 of 14 reasons for EMS calls were associated with the total EMS time in the control 254

period, this proportion dropped to 5 of 15 in the affected period, with the added 255

category of disaster-related calls. 256

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Table 3: Multivariate poisson regression model for total EMS time in the control

and affected period.

Control Period Affected Period

Estim

ate 95% CI P value

Estim

ate 95% CI P value

Constant, minutes 24.0

(23.5-2

4.4)

<0.0

01

**

* 28.6

(27.1-3

0.1)

<0.0

01

**

*

Variable RR 95% CI P value RR 95% CI P value

Age, year

0-14 0.89

(0.88-0

.91)

<0.0

01

**

* 0.79

(0.72-0

.86)

<0.0

01

**

*

15-64

Refere

nce -

Refere

nce -

65- 0.98

(0.98-0

.99)

<0.0

01

**

* 0.98

(0.95-1

.01) 0.18

Sex

Male Refere

nce -

Refere

nce -

Female 0.99 (0.98-1

.00)

<0.0

1 ** 0.97

(0.94-0

.99) 0.02 *

Time of the day

6 AM-12 PM

Refere

nce -

Refere

nce -

12 PM-6 PM 1.01

(1.00-1

.02) 0.17 0.96

(0.93-0

.99) 0.01 *

6 PM-12 AM 1.06

(1.05-1

.07)

<0.0

01

**

* 1.07

(1.03-1

.11)

<0.0

01

**

*

12 AM-6 AM 1.14

(1.12-1

.15)

<0.0

01

**

* 1.06

(1.02-1

.11)

<0.0

1 **

Day of the week

Weekday

Refere

nce -

Refere

nce -

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Weekend 1.01

(1.00-1

.02)

<0.0

1 ** 0.98

(0.95-1

.00) 0.08

Scene of EMS call

Soma†

Refere

nce -

Refere

nce -

Minamisoma 30-

km 0.98

(0.96-1

.00) 0.01 * 0.83

(0.79-0

.87)

<0.0

01

**

*

Minamisoma 20-30

km 0.97

(0.96-0

.98)

<0.0

01

**

* 0.97

(0.94-1

.00) 0.05

Minamisoma -20

km 1.07

(1.06-1

.09)

<0.0

01

**

* 0.95

(0.87-1

.04) 0.30

Iitate 1.07

(1.05-1

.09)

<0.0

01

**

* 1.15

(1.11-1

.20)

<0.0

01

**

*

Other 1.04

(0.98-1

.11) 0.21 1.35

(1.19-1

.53)

<0.0

01

**

*

Reason for EMS

call

Disaster-related - - 1.08

(1.01-1

.15) 0.03 *

Abdominal pain

Refere

nce -

Refere

nce -

Chest pain 1.06

(1.04-1

.08)

<0.0

01

**

* 1.01

(0.95-1

.07) 0.78

CPA 0.97

(0.94-0

.99)

<0.0

1 ** 0.86

(0.79-0

.94)

<0.0

01

**

*

DOC 1.04

(1.03-1

.06)

<0.0

01

**

* 1.02

(0.97-1

.07) 0.44

Fever 1.01

(0.98-1

.03) 0.61 1.05

(0.99-1

.12) 0.09

General weakness 1.07

(1.05-1

.10)

<0.0

01

**

* 1.03

(0.97-1

.10) 0.29

Gynecology 0.91 (0.83-1 0.05 * 0.89 (0.72-1 0.27

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257

258

259

260

261

.00) .10)

Intoxicated 1.13

(1.09-1

.18)

<0.0

01

**

* 1.31

(1.20-1

.44)

<0.0

01

**

*

Neurologic

symptom 1.05

(1.04-1

.07)

<0.0

01

**

* 1.00

(0.95-1

.06) 0.95

Pain, unspecified 1.12

(1.10-1

.15)

<0.0

01

**

* 1.07

(0.98-1

.15) 0.12

Self-harm 1.15

(1.10-1

.21)

<0.0

01

**

* 0.86

(0.76-0

.97) 0.01 *

SOB 1

(0.98-1

.02) 0.74 1.02

(0.96-1

.09) 0.47

Trauma 1.08

(1.06-1

.10)

<0.0

01

**

* 1.02

(0.97-1

.07) 0.55

Other 1

(0.96-1

.03) 0.90 1.11

(1.02-1

.20) 0.02 *

Distance (km)

from FS to scene of

call 1.02

(1.02-1

.02)

<0.0

01

**

* 1.02

(1.02-1

.02)

<0.0

01

**

*

from scene of call

to hospital 1.02

(1.02-1

.02)

<0.0

01

**

* 1.02

(1.02-1

.02)

<0.0

01

**

*

EMS, emergency medical services; RR, relative ratio; CI, confidence interval;

FS, fire station.

*Statistically significant at 0.05 level

**Statistically significant at 0.01 level

***Statistically significant at 0.001 level

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DISCUSSION 262

This study is the first study to assess an EMS system in Fukushima after the triple 263

disaster. The results of this study indicate that the median total EMS time was prolonged 264

from week 1 to 11 after the triple disaster and recovered to the pre-disaster control level 265

from week 12. 266

It is possible that the extension of EMS time from the week 1 to 11 was related 267

to prolonged transport distance from the scene of EMS calls to the hospitals. This 268

hypothesis is supported by several findings. First, results of the multivariable model 269

indicate that the effect of the distance for EMS transport per kilometre on total EMS 270

time was similar in the affected period to that in the control period (RR: 1.02 vs 1.02). 271

Second, the largest change of the three time segments was seen in transport times (Table 272

2), suggesting that the extension of EMS time can be mainly attributed to prolonged 273

transport distance from the scene to the hospitals. Third, the number of the transports 274

per week to hospitals outside Soma district significantly increased, from 5.7 (9.1%) to 275

16.7 (28.4%) while those to hospitals within 30 km from the nuclear plant in 276

Minamisoma City significantly decreased (32.0 vs 13.9, Table 1). 277

As to the reason for distance prolongation, we presume that hospital closures 278

had been a main cause as the affected period was chronologically consistent with the 279

duration of hospital closures, from the timing of the closings of five hospitals in weeks 280

0 and 1 (Figure 1B) until the timing of the reopening of three hospitals in weeks 5, 8, 281

and 14 (Figure E1). There were two kinds of hospital closures in Soma district. First, 282

one of the five hospital was located in the mandatory evacuation area, and forced to 283

evacuate on March 12, 2011. Second, the other four closed hospitals were located in the 284

voluntary evacuation area and it is true that multiple reasons could have led to their 285

closure. However, our discussion with hospital administrators suggest that the main 286

cause of hospital closures in the study area was due to a lack of human resources and 287

material resources including food and drugs in these hospitals. For instance, 288

Minamisoma Municipal General Hospital, with the most bed in Soma district, has 289

closed after 71 of the 239 staff voluntarily evacuated following the nuclear accident 290

without mandatory evacuation orders.27 Voluntary evacuation of hospital staff after a 291

disaster was similarly reported after the Three Mile Island accident or Chi-Chi 292

earthquake.16 28

In all, four emergency hospitals located in the voluntary evacuation area 293

and one in the mandatory evacuation area were closed by week 1 (Figure 1B). As the 294

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hospitals with EDs in Soma district did not suffer from physical damage to the hospital 295

buildings, we presume that the hospital closures were related to staffing issues rather 296

than damage to physical infrastructure. It is of note that EMS staff had continued 297

working even in the evacuation areas, which may highlight a different response to a 298

disaster between hospital and EMS staff. Past studies have indicated that EMS staff may 299

be more likely than other medical staff to take risks for people in need.29 30

It can be 300

hypothesized that hospitals could be more vulnerable to staff shortages than EMS after 301

disasters. 302

Interestingly, this study suggests that the extension of EMS times was not 303

limited to evacuation areas. In the affected period, total EMS time was prolonged in all 304

area of Soma district, not only the 30 km from the nuclear plant where hospital closures 305

occurred. The multivariate analysis suggests that the influence of the call location on 306

total EMS time were similar in the affected period to that in the control period, which 307

indicates that EMS transports from within 30 km from the plant were not delayed more 308

than other areas (Table 3). 309

It is worth nothing that mass casualties from the disaster did not disrupt the EMS 310

system in Soma district in this study. The number of EMS transports was 2.9 higher 311

than that before the disasters in week 0. Approximately one third of these patients were 312

transported due to injuries from the earthquake and tsunami (57/182) while no patient 313

was transported due to acute radiation exposure. In spite of the increased number of 314

transports, total EMS time was not prolonged in week 0. In past disasters, it has been 315

reported that mass casualties can extend total EMS time.31 32

This suggests that the 316

number of casualties of the triple disaster did not overcome the capacity of the EMS 317

systems in Soma district. 318

319

LIMITATIONS 320

Because the EMS database lacks information concerning vital signs, mental 321

status, mortality or outcome, the severity of patient status or the outcome of EMS 322

transport could not be assessed. In addition, due to lack of data on the population of 323

Soma district from March to May, 2011, the relationship between EMS transports and 324

population immediately after the disasters could not be evaluated. 325

This study was unable to assess transports within a 10 km radius of the nuclear 326

plant because Soma Regional Fire Department did not cover this area. As a result, the 327

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areas investigated in this study were restricted to places with relatively low radiation 328

levels, and the results of this study may not be applicable to areas significantly 329

contaminated in radiation-release accidents. 330

331

CONCLUSION 332

This study shows that the elapsed time in EMS transport was significantly prolonged 333

from week 1 to 11. These delays were likely attributable to the closure of hospitals with 334

emergency departments after the nuclear disaster. 335

336

Acknowledgements 337

We are grateful to all of the staff in emergency departments or hospitals in Soma district 338

who have managed patients in the aftermath of the disasters. 339

340

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LEGEND 453

Figure 1A: Five regions of the study area according to evacuation orders by the 454

government after the nuclear accident; 1) Minamisoma, within 20 km of the plant; the 455

area under mandatory evacuation orders after March 12, 2011, 2) Minamisoma, 20 to 30 456

km from the plant; designated as a voluntary evacuation area from March 15 to April 22, 457

2011, 3) Minamisoma, further than 30 km from the plant; under no evacuation orders, 458

4) Iitate; a rural mountain area located 25 to 45 km northwest of the nuclear plant, under 459

mandatory evacuation orders after April 11, 2011, and 5) Soma; an area located more 460

than 40 km to the north from the plant, under no evacuation orders. 461

462

Figure 1B: The periods of hospital closures. Each letter corresponds to the hospital ID 463

in Figure 1A. 464

465

Figure 2A: Definition of three time segments of total EMS time. 466

467

Figure 2B: Description of the time course of study period: the duration during which 468

total median EMS time had been significantly affected by the disasters, starting from 469

week 0, March 11th to 17th in 2011. 470

471

Figure 3: Trends in the number of EMS transports and median total EMS time. The 472

week of the earthquake (March 11-17 in 2011) is defined as week 0. 473

474

Figure 4: The dense curves of total EMS time and three time segments; response time, 475

on-scene time, and transport time during the control and affected period. 476

477

Table 1: Characteristics of EMS transports of the control and affected period. 478

Table 2: Comparison of EMS time between the control and affected period 479

Table 3: Multivariable poisson regression model for total EMS time in the control and 480

affected period. 481

482

Web Appendices 483

Figure E1: The relationship of total EMS time and the timing of closing and reopening 484

of hospitals. Each letter corresponds to the hospital ID in figure 1. 485

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Table E1: Comparisons of total EMS time per week. 486

487

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Contributorship statement: TM, MT, MK, and TO developed the concept and 488

designed the study. SO, KT and SK supervised the data collection. TM, MT, YS, SF and 489

CL collected and managed the data, including quality control. SN and TF provided 490

statistical advice on study design and analysed the data. TM drafted the manuscript, and 491

all authors contributed substantially to its revision. TM takes responsibility for the paper 492

as a whole. 493

Funding statement: There is no funding to report for this submission 494

Competing interests: None declared. 495

Data sharing statement: No additional data are available. 496

497

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Five regions of the study area according to evacuation orders by the government after the nuclear accident; 1) Minamisoma, within 20 km of the plant; the area under mandatory evacuation orders after March 12, 2011, 2) Minamisoma, 20 to 30 km from the plant; designated as a voluntary evacuation area from March 15 to April 22, 2011, 3) Minamisoma, further than 30 km from the plant; under no evacuation orders, 4)

Iitate; a rural mountain area located 25 to 45 km northwest of the nuclear plant, under mandatory evacuation orders after April 11, 2011, and 5) Soma; an area located more than 40 km to the north from

the plant, under no evacuation orders. Figure 1A

271x191mm (300 x 300 DPI)

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The periods of hospital closures. Each letter corresponds to the hospital ID in Figure 1A. Figure 1B

338x190mm (300 x 300 DPI)

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A: Definition of three time segments of total EMS time. B: Description of the time course of study period: the duration during which total median EMS time had been significantly affected by the disasters, starting

from week 0, March 11th to 17th in 2011. Figure 2

338x190mm (300 x 300 DPI)

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Trends in the number of EMS transports and median total EMS time. The week of the earthquake (March 11-17 in 2011) is defined as week 0.

Figure 3 271x198mm (300 x 300 DPI)

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The dense curves of total EMS time and three time segments; response time, on-scene time, and transport time during the control and affected period.

Figure 4

219x278mm (300 x 300 DPI)

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338x190mm (300 x 300 DPI)

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n median IQR n median IQR chi sq. P value †0 162 29 19 125 30 13 0.04 0.831 62 41 29 121 31 18 14.04 0.002 49 48 36 105 29 14 24.12 0.003 32 38 22 122 30 15 5.67 0.024 56 42 31 126 31 20 17.76 0.005 34 40 27 126 31 13 15.24 0.006 39 36 18 116 27 12 6.33 0.017 50 39 26 147 35 21 3.64 0.068 41 32 17 129 30 18 3.08 0.089 51 42 26 109 32 17 6.53 0.01

10 52 34 13 107 30 15 7.07 0.0111 51 31 16 119 28 10 4.14 0.0412 44 32 11 107 30 19 0.70 0.4013 51 35 14 116 30 13 8.28 0.0014 43 32 10 113 29 16 2.07 0.1515 42 29 8 94 30 18 0.30 0.5816 52 32 13 134 32 21 0.16 0.6917 54 30 14 133 29 16 0.18 0.6718 47 33 12 151 33 19 0.24 0.6319 49 31 13 141 29 18 0.36 0.5520 53 30 13 132 28 10 1.15 0.2821 59 31 12 145 31 16 0.28 0.6022 79 30 9 168 32 18 0.00 0.9823 49 30 11 127 32 15 0.88 0.3524 50 34 10 116 30 15 2.39 0.1225 52 33 16 123 30 14 3.17 0.0726 39 33 11 127 32 22 0.03 0.8527 57 33 16 98 30 21 1.49 0.2228 55 30 19 123 29 14 0.28 0.6029 55 33 14 116 30 17 2.01 0.1630 51 32 17 122 33 19 0.07 0.7931 51 31 15 134 31 18 0.00 0.9632 52 31 11 112 30 16 0.05 0.8333 52 31 12 113 29 15 0.26 0.6134 41 29 10 135 29 16 0.21 0.6535 52 32 11 129 30 19 1.12 0.2936 54 34 13 133 34 21 0.07 0.8037 57 33 17 141 33 17 0.02 0.8938 43 33 10 114 33 14 0.03 0.8739 61 32 15 124 32 16 1.35 0.2540 52 30 17 128 31 17 0.69 0.4141 48 33 12 155 31 18 1.27 0.26

Table E1. Comparisons of total EMS time per week.

† The P value was calculated with the use of a Mann-Whitney U test.

Week2011 vs Control2011 Control Period

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