assuring data quality dept. of healthcare-associated infection & antimicrobial resistance,...
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Assuring Data Quality Assuring Data Quality
Dept. of Healthcare-Associated Infection & Antimicrobial Resistance,Health Protection Agency
Jennie WilsonProgramme Leader – SSI Surveillance
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AT BE DE ES FI FR HU LT NL NO UE UN US UW
1164 544 5987 379 3896 4775 1203 473 6011 1007 39678 3933 8462 2098
N=6 N=6 N=54 N=5 N=6 N=200 N=7 N=6 N=33 N=20 N=172 NA NA NA
N in
-hospita
l SS
I/1000 p
ost-
op. pt.-d
ays
0.0%
1.0%
2.0%
3.0%
4.0%
5.0%
6.0%
7.0%
8.0%
AT BE DE ES FI FR HU LT NL NO PL UE UN US UW
1166 544 30478 379 6103 4844 1203 474 6081 1009 1325 39684 3941 8764 2250
N=6 N=6 N=100 N=5 N=12 N=200 N=7 N=6 N=34 N=20 N=17 N=172 NA NA NA
SS
I cum
ulat
ive
inci
denc
e (%
)
2005 Hip prosthesis: inter-country rate (incidence density)
2005 Hip prosthesis: inter-country rate (cumulative incidence)
External benchmarksExternal benchmarks
External benchmarks are a powerful driver for effecting change, but require
standardised data collection methods
standardised analysis
high data quality
central co-ordination
Gaynes 1997
Why is data quality so Why is data quality so important locally?important locally?
Do you know whether action is required?• real problems?• poorly collected data?
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Apr-Jun 2004 Jul-Sep 2004 Oct-Dec 2004 Jan-Mar 2005 Apr-Jun 2005P e rio d
SSI SurveillanceSSI SurveillanceBasic methodologyBasic methodology
Targeted at categories of clinically similar
operative procedures
Data collection form completed for each relevant
operation (denominator)
Systematic (active) surveillance after each
operation to detect infections (numerator)
Methods of identifying patientsMethods of identifying patientswith SSI (numerator)with SSI (numerator)
Active
Designated, trained personnel, use a variety of data sources to determine whether an HAI has occurred
Sensitivity = 85-100%
Passive
HAI identified and reported by people other than designated, trained personnel. Requires fewer people but unreliable, definition not applied consistently
Sensitivity: 14-34%(Perl, 1998)
Surveillance methods:Surveillance methods:Sensitivity of case findingSensitivity of case finding
Lab-based phoneSensitivity 36%1.2hrs / 100 beds / week
Temperature / treatment chartSensitivity 65%6.5 hours / 100 beds / week
Lab-based, ward liaisonSensitivity 76%6.4 hours / 100 beds / week
Glenister et al 1992Glenister et al 1992
Systematic surveillance for SSI Systematic surveillance for SSI Lab-based ward liaisonLab-based ward liaison
1. Visit ward/patient 3 times per week– discuss patients with ward staff
– check medical / nursing records
– check temperature / treatment charts
2. Review microbiology reports daily– identify positive surgical site reports
Definitions of surgical site Definitions of surgical site infection (CDC)infection (CDC)Superficial incisional
• involves only skin or subcutaneous tissue• occurs within 30 days of surgery
Deep incisional
• involves fascial or muscle layers• occurs within 30 days, implants within 1
year
Organ/space
• part of anatomy opened / manipulated • infection appears related to surgery• occurs within 30 days, implants within 1
year
Superficial Incisional InfectionSuperficial Incisional Infection
Must meet one of the following criteria:
1. Purulent drainage from superficial incision
2. Culture of organisms from fluid/tissue
3. At least 1 symptom of inflammation (pain, tenderness, localised swelling, redness, heat) and incision deliberately opened to manage infection
4. Clinicians diagnosis of superficial SSI
Deep Incisional InfectionDeep Incisional Infection
Must meet one of the following criteria:
1. Purulent drainage from deep incision
2. Deep incision dehisces / deliberately opened and patient has 1 symptom : fever, localised pain/tenderness
3. Abscess / other evidence of infection in deep incision: re-operation / histopathology /
radiology
4. Clinicians diagnosis of deep infection
Identifying SSIIdentifying SSI
Review patients systematically whilst they are in hospital
Do not rely on reviewing case-notes after discharge to find SSIs
If a patient is prescribed antibiotics do not assume these are for SSI – check with clinician
Check significance of positive microbiology cultures
Make sure any SSI identified post-discharge also meets the definition
Is this an SSI…….?Is this an SSI…….?
Nursing record states:
‘Wound oozing ++ from small lower section. Pressure dressing applied’
Oozing what:
•Clear (serous) fluid, blood, pus?
What was the condition of the suture line?
•Red, swollen, dehisced
Was a wound swab taken, if so why?
Criteria for SSI checklistCriteria for SSI checklistWeblink data entry (SSISS)Weblink data entry (SSISS)
Validation studiesValidation studies
Mannien et al 2007: PREZIES, Netherlands
• Reviewed 859 medical charts; 149 SSI
• Validation team = ‘gold standard’
• PPV = 0.97; NPV = 0.99
McCoubrey et al 2005: SSI surveillance, Scotland• 91 SSI reported validated by case note review
• 10/27 hospitals criteria not recorded
• PPV 94.6% (95%CL 87.9 – 98.2); NPV 99.4 (95% CL 98.3 – 99.9)
(assuming not recorded data valid)
NNIS SSI ‘Risk Index’NNIS SSI ‘Risk Index’
Each operation is scored, and results stratified, using 3 major
risk factors associated with SSI*:
• ASA pre-operative assessment score
• Wound class
• Duration of surgery (T time)
Score between 0 and 3
*Culver et al (1991)
Risk Index factorsRisk Index factors
ASA classification of physical illness
1: normal healthy patient
2: mild systemic disease
3: severe systemic disease
4: incapacitating systemic disease
5: moribund, little chance of survival
Wound classification
Clean: no signs of infection, no body ‘tracts’
Clean-contaminated: body tract entered
Contaminated: spillage form GIT, inflammation, open trauma
Dirty: pus, perforated viscera, delayed open trauma, faecal contamination
Changed by pre-op and intra-op events
T timeT timeassociation between p value and cut point for duration association between p value and cut point for duration of operation (abdominal hysterectomy)of operation (abdominal hysterectomy)
Leong et al 2006
Trend in rate Trend in rate of SSI by Risk of SSI by Risk index groupindex group
0
5
10
15
20
25
30
35
% in
fec
ted
0 1 2 3 u/k All
Risk Index Group
Vascular surgery
0
5
10
15
20
25
% in
fec
ted
0 1 2 3 u/k All
Risk Index Group
Large bowel surgery
Effect of indirect standardisation on Effect of indirect standardisation on crude rates of SSI (vascular surgery)crude rates of SSI (vascular surgery)
Rate of SWI (%)
crude adjusted
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5
10
15
20
0
5
10
15
20
25
% o
pera
tions
infe
cte
d
Abdom
ial h
yste
rect
omy
Bile d
uct,
liver
or p
ancr
eatic
surg
ery
Coron
ary A
rtery
Byp
ass
Graft
Gas
tric s
urge
ry
Total
hip re
plac
emen
t
Hip h
emiar
thro
plasty
Knee
repla
cem
ent
Larg
e bo
wel su
rger
y
Lim
b am
puta
tion
Ope
n re
ducti
on o
f fra
cture
Small
bow
el su
rger
y
Vascu
lar s
urge
ry
Percentiles90th
75th
50th
25th
10th
Distribution of the incidence of surgical site infectionby category of surgical procedures
Source: SSI Surveillance Service, CDSC
October 1997 to December 2003
Crude rates of SWI for Crude rates of SWI for vascular surgery (95% vascular surgery (95%
CL) by hospitalCL) by hospital
0
5
10
15
20
25
30
35
40
45
0 5 10 15 20 25 30 35 40
Order
Rat
e o
f S
WI
(%)
Hospital
90th percentile
50th percentile
Data to December 2001
Funnel plots used to account Funnel plots used to account for variation in sample sizefor variation in sample size
Total hip prosthesis, January 2000 – March 2005
05
1015
2025
Cu
mul
ativ
e in
cide
nce
0 1000 2000 3000 4000number of operations
95% CI 99% CI
Hospital
Cumulative incidence
2.01
0.65
4.05
1.24
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
Open reductionlong bone fracture
Knee prosthesis
Hiphemiarthroplasty
Total hipprosthesis
% infected
1.67
0.76
2.29
1.36
0.0 0.5 1.0 1.5 2.0 2.5
Open reduction of long bone fracture
Knee prosthesis
Hip hemiarthroplasty
Total hip prothesis
Incidence density per 1000 days
Cumulative incidenceCumulative incidence
Incidence densityIncidence density
Funnel plots to adjust for variation in Funnel plots to adjust for variation in sample size and length of post-op staysample size and length of post-op stay
05
1015
Inci
den
ce D
ens
ity
0 10000 20000 30000 40000in-patient post-operative days
95% CI 99% CI
Hospital
Incidence density/ 1000 post-op in-patient days
Length of stay inLength of stay in elective surgery is reducing elective surgery is reducing
02468
10121416
1998 1999 2000 2001 2002 2003 2004
Year
Me
dia
n le
ng
th o
f s
tay
Total hips Total knee Hip hemi
Proportion of SSI detectedProportion of SSI detectedpre & post dischargepre & post discharge
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10
20
30
40
50
60
Nu
mb
er
of
SS
Is Post discharge
Pre-discharge
Barrett et al 2000
Post-discharge surveillance Post-discharge surveillance studystudy
Post-discharge surveillance method Resources +++ - data collection, informing/contacting patients
General practitioners/district nurses – poor response rate to questionnaire
Patients – better response; +/- reliability
Sensitivity of case-findingactive vs. passive surveillance
reliability
Barrett et al 2000
Response rate to PDS Response rate to PDS patient questionnairespatient questionnaires
n = 615951%
22%27%
No Response
Response No Reminder
Response With Reminder
Barrett et al 2000
Response rate affected by ethnic group and age