fear-avoidance beliefs, perceived lumbar exertion ......1 116167 fear-avoidance beliefs, perceived...
TRANSCRIPT
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116167
Fear-avoidance beliefs, perceived lumbar exertion, musculoskeletal fitness, and
multi-site pain contribute to pain intensity, physical functioning, and perceived
ability to work in female health-care personnel with recurrent low back pain
Annika Taulaniemi1, MSc
Lotta Kuusinen2, MD
Kari Tokola1, MSc
Markku Kankaanpää2, PhD
Jaana H. Suni1, DSc
1 UKK Institute for Health Promotion Research
2 Tampere University Hospital
short title: Descriptors of low back pain in nursing personnel
2
Abstract
Objective: To study associations between physical and psychosocial risk factors for chronic low
back pain (LBP) and outcomes representing various domains of the ICF model, assessed through
pain intensity, physical functioning, and work ability
Design: Cross-sectional study
Subjects: 219 female health-care workers with recurrent non-specific LBP
Methods: Associations between several risk factors and outcomes of bodily pain and pain
interfering with normal work, physical functioning, and ability to work were studied. Bivariate
correlations between risk factors and outcome variables were studied first. Secondly, variables with
statistically significant correlation (p<0.05) were set within a generalised linear model to analyse
their contribution to each outcome.
Results: Work-induced lumbar exertion (p<0.001), multi-site pain (p<0.001), and work-related
fear-avoidance beliefs (FAB-W) (p=0.02) were associated with bodily pain. Multi-site pain
(p<0.001), perceived lumbar exertion (p=0.005), FAB-W (p=0.01), and physical performance in
figure-of-eight running (p=0.01) and modified push-ups (p=0.05) were associated with physical
functioning; FAB-W (p<0.001), lumbar exertion (p=0.003), depression (p=0.01), and recovery after
work (p=0.03) were associated with work ability. In addition, there was an association between
lumbar exertion and poor physical performance.
Conclusion: FAB-W and perceived lumbar exertion contribute to pain, physical functioning, and
work ability. Good physical performance capacity may reduce work-induced lumbar exertion.
Keywords: Lower Back Pain; International Classification of Functioning, Disability and Health;
Biological Factors; Psychological Factors
Journal of Rehabilitation Medicine
Annika Taulaniemi
The UKK Institute for Health Promotion Research
Kaupinpuistonkatu 1, 33500 Tampere, Finland
3
Introduction
Low back pain (LBP) is a bio-psychosocial, multidimensional, complex, and costly problem and is
a leading cause of years lived with disability(1). In the majority of low back pain patients (85–
90%), the pain is classified as non-specific low back pain (NSLBP). After an acute pain episode,
most recover, but in 50–70% the pain recurs within the following year and in 10% it becomes
chronic (2). The prevalence of LBP varies between occupational groups. Workers in physically
demanding jobs are known to have increased risk (3). Among health-care workers, the one-year
prevalence of LBP has been found to be as high as 45–77% (4), which is high in comparison to
other occupations.
Preventing new LBP episodes (i.e., recurrence) is considered to be of importance for prevention of
persistent pain. Low back pain is often a long-term or recurrent condition wherein individuals
experience repeated pain episodes that are not independent of each other (5). Longer-time follow-up
studies (6, 7) indicate that the majority of people with LBP indeed experience back pain off and on
over an extended span of time.
Risk factors for development of chronic disability from LBP are related more closely to
psychosocial and psychological factors than to spine condition itself (8, 9). Fear-avoidance beliefs
(FAB), job satisfaction, and anxiety are known to be associated with the problem of chronicity (10).
On the other hand, there is also increasing evidence that low performance levels for several
components of physical fitness are risk factors for LBP (11, 12), although scientific evidence about
those associations is still partly conflicting. Nursing duties include large amounts of heavy physical
work and psychosocial stress, which are known to be risk factors for LBP (13).
The World Health Organization (WHO) has presented the International Classification of
Functioning, Disability and Health (ICF) model, aimed at providing a scientific basis for
Kommentar [KJ1]: Please give references
4
understanding and studying health and health-related states, outcomes, and determinants (14). There
are ICF Core Sets developed for various health conditions, including LBP (15).
The ICF model comprises five main components: (i) body structures and functioning, (ii) activities,
(iii) participation, (iv) environmental factors, and (v) personal factors. Each of these main domains
can be subdivided into chapters and further categories (14). The ICF is a useful tool in structuring
numerous bio-psychosocial measurements into logical and understandable entities and for analysing
their associations with various outcomes.
For preventing new episodes of LBP and pain chronicity it is essential to understand these links
between several biological and psychosocial factors influencing the early stages of recurrent LBP,
especially in a population performing physically demanding work.
The purpose of the cross-sectional study was to assess predictors of sub-acute outcomes of LBP in
a sample of female health-care personnel with recurrent non-specific LBP, with the ICF model as
the framework. More specifically, it examined associations between bio-psychosocial risk factors
that might influence bodily pain and pain interfering with normal work, physical functioning, and
ability to work.
MATERIALS AND METHODS
Study design and participants
The cross-sectional study was part of a randomised controlled trial (the NURSE RCT, clinical trial
registration NCT04165698) aimed at reducing pain, movement-control impairment, and fear-
avoidance beliefs in working female health-care personnel with recurrent non-specific LBP. The
study was approved by the Ethics Committee of Pirkanmaa Hospital District, Finland (ETL code
R08157). Data from the baseline measurements in the NURSE RCT were analysed in the study
reported upon here.
Gelöscht: cross-sectional
5
The target population was female health-care personnel working in wards with bed patients or other
nursing tasks that include lifting patients, transfer, or other postures that are awkward for the lower
back. To be eligible, individuals had to meet the following criteria: (i) being a woman aged 30–55
who (ii) had worked in her current job for at least 12 months and (iii) experienced LBP of intensity
2 or above on the numeric rating scale (NRS; 0–10) (16) within the preceding four weeks. The
exclusion criteria for the study were (i) a serious earlier back injury (fracture, surgery, or disc
protrusion), (ii) chronic LBP as diagnosed by a physician or self-reporting of continuous LBP over
the past seven months or longer, (iii) a serious other disease or symptoms limiting participation in
moderate-intensity neuromuscular exercise, (iv) engaging in neuromuscular-type exercise more than
once a week, and (v) pregnancy or recent delivery (<12 months).
More precise information on recruitment in its three sub-studies is available in the protocol article
on the NURSE RCT (17). The total sample consisted of 219 health-care workers, working in
community- or university-hospital wards, old people’s homes, home service, and public health-care
units in the city of Tampere, Finland. Figure 1 summarises the recruitment process.
Study procedures and measurements:
The measurements for all three sub-studies were conducted in 2011–2013 at the UKK Institute for
Health Promotion Research, in Tampere. Informed consent was obtained in writing from all
participants on the first visit. Specially educated personnel with a long work history conducted all
measurements. Health screening was performed before fitness testing, in accordance with the safety
model of the Health-related Fitness Test Battery for Middle-aged Adults (18). The measurement
battery consisted of questionnaires, assessment of health-related fitness tests’ results, and
objectively measured physical activity / sedentary time over one week. The description of
measurements used in the study is presented in line with the ICF model.
Outcome measures (dependent variables):
Kommentar [KJ2]: and
Kommentar [KJ3]: demanding
Kommentar [KJ4]: Were all measures taken at one single session?
6
Body structures and functioning: Bodily pain and pain interfering with normal work (sum score
from the two questions concerning pain in the RAND-36 Health Survey (19), which consists of one
five-point-scale and one six-point-scale rating. Ratings were re-coded in accordance with
predetermined numbers, with the sum scores for the recoded values being 0 (very severe pain and
extreme difficulties) to 100 (no pain and no difficulties).
Activities: Physical functioning (sum score from 10 questions from the RAND-36 survey) (19). The
item consists of 10 ratings on a three-point scale (limited a lot, limited a little, not limited at all).
Ratings were recoded to predetermined numbers, with the sum score interpreted thus: 0 = limited a
lot … 100 = not limited at all.
Participation: Self-assessed current and future ability to work (sum score from four questions, 3–27
scale (3 = poor … 27 = the best possible) (20).
Risk factors for low back pain (independent variables):
Body structures and functioning:
Number of musculoskeletal pain sites.
Body mass index (BMI), in kg/m2.
Depression; Beck Depression Inventory, short form (sum score from nine questions with a 1–4
rating scale) (21), where high values indicate higher levels of depression.
Flexibility (trunk lateral flexion; cm) (22).
Perceived recovery from work (on a five-point scale: 1 = recovering well … 5 = not recovering).
Ratings were re-coded to tertiles.
Kommentar [KJ5]: How did you compute the 0-100 score?
Kommentar [KJ6]: give reference or explain
Kommentar [KJ7]: same remark here. Please try to clarify. The aim is that readers can repeat the procedure. Looking at the reference, it seems you did not use the work ability index WAI. This is one of the primary outcomes so use some sentences to explain. Give questions and responses (e.9. 1= ... -9=...)
Kommentar [KJ8]: Procedure, number of sites, You may present body chart in additional file. Reference?
Kommentar [KJ9]: Fingertips to floor? How did you account for length?
Kommentar [KJ10]: Explain. E.g. ’daily after work, on average during the past week’?
Kommentar [KJ11]: how
7
Perceived exertion in various anatomical body parts after work (1–5 scale: 1 = no exertion at all …
5 = high exertion) over the preceding four weeks(23). The sum score measured exertion in eight
distinct physical parts of the body.
Perceived exertion after work in the low back (1 = no exertion … 5 = high exertion)(23). Five-
point-scale ratings were recoded to tertiles.
Tiredness and sleepiness (sum score from three questions developed by Finnish Institute of
Occupational Health; 3 = no tiredness or sleepiness… 13 = long-term, daily tiredness and
sleepiness)(24). The questions concern tiredness in the morning after woken up, and tiredness and
sleepiness during the day-time.
Activities:
Aerobic fitness assessed via a six-minute-walk test (6MWT), for maximal walking distance
(metres) in six minutes (25).
Muscle strength assessed via (i) modified push-ups, number of repetitions in 40 seconds; (ii) one-
leg squats, number of repetitions, with progressively increasing external load; and (iii) vertical
jump, cm (22).
Agility as assessed by running of a figure of eight, via running time in seconds (26).
Participation:
Health-related physical activity:
Objectively measured aerobic physical activity (using a Hookie AM20 tri-axial accelerometer, from
Traxmeet, Espoo, Finland), with recoding of data on meeting recommendations for at least three
times a week (27), yes/no.
Kommentar [KJ12]: Which? Did you use all regions? Add subscores?
Kommentar [KJ13]: Sum score? Or each muscle group was analysed?
Kommentar [KJ14]: Unclear, I assume subjects wore the accellerometers during three days the whole day or during wake hours or durinh work?
8
Meeting of recommendations for muscle-strengthening training at least twice a week (27), yes/no
(questionnaire).
Personal factors:
Fear-avoidance beliefs (FAB). Two sub-scales exist in the fear-avoidance beliefs questionnaire
(FABQ): an eight-item work (FAB-W) sub-scale (range: 0–48 points; three questions considering
long-term sick leave were excluded from the original FABQ) and a five-item physical-activity
(FAB-P) sub-scale (range: 0–30 points). High values indicate increased levels of fear-avoidance
beliefs. (28, 29)
Content and placement of risk factors and outcome measures are presented in Figure 2, according to
the ICF model.
Also, psychosocial factors at work (such as work stress) were assessed via a Finnish questionnaire
(30). Those variables were used in the study only for adjustments.
Statistical analysis
For the descriptive analyses, the mean and standard deviation (SD) were calculated for normally
distributed data, and medians (Md) and quartiles (Q1,Q3) for skewed distributions. Correlations
between interval-scale measurements were analysed via Pearson’s correlation coefficient (r) in
cases of normal distributions and via Spearman’s rank correlation coefficient (rs) in cases of skewed
distributions.
Associations between categorical and normally distributed interval-scale variables were analysed
via one-way analysis of variance (ANOVA) for tertiles and via independent-samples t-test in cases
of binominal variables. The corresponding statistical tests for non-normal distributions were the
Kruskal–Wallis test and the Mann–Whitney test.
Kommentar [KJ15]: Why not as independent variable?
9
When statistically significant associations (p<0.05) between individual factors from the ICF model
and selected main outcomes were calculated in bivariate analysis, generalised linear models (GLMs)
were used to determine the contribution of the factors and covariates to dependent outcome
measurements: bodily pain and pain interfering with normal work, physical functioning, and
perceived ability to work. After calculation of crude β-coefficients, the analyses were adjusted first
for age, BMI, and work type (shift work / regular work), and after that also for hormonal status and
work satisfaction.
All analyses were conducted with the SPSS statistical analysis package, version 22.
RESULTS
Description of the study population
Baseline characteristics of the study sample are reported in Table 1. The study subjects had worked
in their current position for, on average, 11.4 years. More than 85% of them were nurses or nursing
assistants, and 70% had irregular working hours. Most perceived their health to be average or good,
but 28% perceived their fitness to be poor in comparison to that of persons the same age and
gender. Only approximately 40% were of normal body weight, and 60% were considered to be
overweight or obese.
At the pre-study screening, the pain intensity for all people who were included in the study was
more than 2 (mean 4.7, SD 1.8), measured on NRS (1–10). Most of the study subjects (82%)
experienced LBP on a few or most days of the week but not daily, and 18% had daily LBP. The
corresponding percentages at the baseline measurement were 72% and 12%, and 16% had
recovered from pain.
Gelöscht: investigated
Kommentar [KJ16]: Figure 1 sows some exclusions after baseline measures. What was the reason?
Kommentar [KJ17]: Were there no missings? If yes, how did you handle missings?
10
Descriptive data for the measurements are presented in Table II. Participants perceived themselves
as having moderate bodily pain and pain interfering with normal work: mean 63.1 (SD 19.0) on a
0–100 scale (0 = very severe pain / extreme difficulties … 100 = no pain/difficulties). The median
for physical functioning was 90 (Q1=80,Q3=95, scale 0–100), and the median for self-assessed
current and future work ability was 23 (Q1=21, Q3=24, scale 3–27).
Bivariate analysis
The correlation of the various risk factors from ICF-domains (a) body structures and functioning,
(b) activities, and (c) personal factors with the outcome variables (i) bodily pain and pain interfering
with normal work, (ii) physical functioning, and (iii) work ability were calculated. These are
presented in Table III.
Associations between categorical risk factor variables and outcome variables are presented in Table
IV. Perceived lumbar exertion was associated with physical pain and pain interfering with normal
work (F=17.82, df=207, p<0.001). Those who perceived themselves very exerted in the low back
after work had more pain and pain interfering with normal work than did those who perceived little
exertion (mean difference 17.4, 95% confidence interval (CI) 9.9, 24.9, p<0.001) or moderate
exertion (mean difference 13.3, 95% CI 6.3, 24.4, p<0.001). Perceived exertion in the low back was
also associated with levels of physical functioning (p<0.001). Those with little low-back exertion
after work had a higher score for physical functioning than those who experienced moderate or high
exertion. Perceived lumbar exertion was associated also with levels of work ability (p<0.001); little
exertion was linked to higher work-ability scores than more exertion was.
Recovery from work was associated with physical functioning (p=0.003). Those who were
recovering well had higher scores for physical functioning than participants who had some
difficulties in recovering or who felt that they were not recovering after work.
Kommentar [KJ18]: Dependent and independent variables (’measures’ is too broad, are also taken for Table 1)
Kommentar [KJ19]: Self rated
Kommentar [KJ20]: Continuous? Next are categoriacal.
11
Post-work recovery was associated with perceived work ability (p<0.001). Subjects who were
recovering well had higher work-ability scores than those who had some difficulties in recovering
or who did not recover after work.
Higher values for physical functioning were detected in those who met recommendations for
aerobic exercise (U=-1.96, p=0.05) and strength training (U=-2.26, p=0.02) than in those who did
not meet the recommendations.
Multivariable analysis
The results of the GLM-based analysis are presented in Table V and visualised in Figure 3.
The risk factors associated with having bodily pain and pain interfering with normal work were
perceived lumbar exertion after work (high exertion vs. little exertion, β=-13.95, p<0.001, n=206),
FAB related to work (β=-0.44, p=0.02, n=206), and number of musculoskeletal pain sites (β=-3.06,
p<0.001, n=206). Negative β coefficients are explained by coding of bodily pain with descending
values: a high score indicates no pain. When the analyses were adjusted for age, BMI, work type
(shift/regular work), hormonal status, and work satisfaction (including work-related stress),
statistically significant associations were found also between work type (β=-10.74, p<0.001), work
stress (β=-4.53, p=0.05), and bodily pain.
Lower perceived lumbar exertion after work (β=-0.075, p=0.005, n=174), lower values for FAB
related to work (β=-0.004, p=0.01, n=174), a higher number of modified push-ups (β=0.008,
p=0.045, n=174), and shorter times for running a figure of eight (β=-0.033, p=0.01, n=174) were
associated with better physical functioning. No significant changes were detected after adjustments.
Lower perceived lumbar exertion after work (β=-0.052, p=0.003, n=192), lower FAB related to
work (β=-0.004, p<0.001, n=192), lower scores for depression (β=-0.003, p=0.045, n=192), and
Kommentar [KJ21]: Multivariate?
Kommentar [KJ22]: Am I right that these are not in Table V? Wouldn’t it be better to add these independent variables there too?
12
higher scores for perceived recovery after work (β=-0.03, p=0.03, n=192) were associated with
greater work ability. No significant changes were detected after adjustments.
Additional analysis:
Perceived lumbar exertion after work contributed to all three main outcomes: levels of bodily pain,
physical functioning, and perceived ability to work. In consequence, we calculated the associations
between fitness levels and perceived lumbar exertion via ANOVA. The results are presented in
Table VI. Fitness results were consistently lower in those who perceived more lumbar exhaustion
after work in comparison to subjects who were nowhere near exhausted. All differences were
statistically significant.
DISCUSSION
The study’s purpose was to assess and identify cross-sectional associations between physical and
psychosocial risk factors for chronic LBP and outcome measures representing different domains of
the ICF model among nursing personnel with NSLBP. The main outcome measures were (i) bodily
pain and pain interfering with normal work, (ii) physical functioning, and (iii) perceived current and
future ability to work. The results indicate that perceived lumbar exertion after work and work-
related FAB contributed to all outcome measures: levels of pain, physical functioning, and work
ability. Multi-site musculoskeletal pain contributed to pain, and physical functioning and
musculoskeletal performance level (assessed via modified push-ups) contributed to physical
functioning and work ability.
Body structures and functioning
The outcome measure for the first ICF domain was bodily pain and pain interfering with normal
work. We chose a sub-scale for bodily pain from RAND-36 (19) in preference to a visual analogue
Kommentar [KJ23]: explain
13
scale (VAS) (1–100) (31), because we considered it more informative in a population performing
physically demanding work. Perceived lumbar exertion, multi-site pain, and FAB-W all contributed
to perceived pain. After adjustments, work stress too was associated with pain. Work stress has
already been shown to be associated with musculoskeletal disorders, especially LBP, in nurses (32).
The average number of musculoskeletal pain sites was 3.2 in the study sample. Multi-site pain
seems quite commonplace in nursing personnel, with prevalence within the past year having been
found to be 60% among Estonian nurses (33). Multi-site musculoskeletal pain is a strong predictor
of sickness-related absences (34) and early retirement (35). In a recent cross-sectional study
conducted among health-care providers (36), multi-site musculoskeletal pain was associated with
perceived work ability, with the magnitude of association likely to increase with the number of pain
sites.
Depression contributed to levels of perceived current and future work ability. If one is having dark
thoughts about the present, the perceived prognosis for work ability too may be bleak. In a recent
systematic review (37), Pinheiro et al. suggested that depression might have an effect on LBP
prognosis also in the acute or sub-acute phase.
Also, shift work contributed to pain. Most of the study subjects performed irregular shift work,
which is often associated with sleep disturbances and poor recovery. These, in turn, can affect
perceptions of pain (38).
Activities
‘Activities’ and ‘participation’ domains are often considered in combination because of difficulty in
differentiating the two concepts (39). For the present study, we chose not to combine those
domains, because limitations and restrictions to activities and participation may be most relevant to
patients with LBP (15). Impairments in physical functioning have been shown to be one of the most
important components in predicting persistent, disabling LBP(40).
14
Fitness level in the modified push-up test contributed to physical functioning, and it was strongly
associated with levels of perceived lumbar exertion after work. The modified push-up test requires
both upper-body muscular strength and trunk stabilisation, and low performance levels in this test
have been associated with low-back dysfunction and pain in middle-aged subjects (41). Increased
risk of LBP has been reported also in young conscripts with poor fitness in terms of trunk-muscle
endurance and aerobic performance (12).
Muscle strength and power of the lower extremities are commonly considered important capacities
when one is lifting and transferring patients in nursing duties, along with keeping the back in
neutral position, although scientific evidence of associations between LBP and leg strength is
limited. It can be assumed that nursing personnel with poor strength and power in the lower
extremities are more prone to use their back musculature in lifting and transferring patients, and
they might perceive lumbar exertion for this reason. In our study, poor results in running a figure of
eight (which requires agility and power in the lower extremities) contributed to poor physical
functioning in GLM analysis, and number of one-leg squats was strongly linked with perceived
levels of low-back exertion.
In the study, we found that performance levels in aerobic, motor, and musculoskeletal fitness tests
were systematically lower in those who perceived more lumbar exhaustion after work in
comparison to those who were less exhausted. Poor endurance leads to exhaustion and fatigue at the
end of a work shift, and fatigue, in turn, is known to decrease perception abilities and motor control
(42), thereby intrinsically raising the risk of injury in physically demanding tasks. Perceived lumbar
exertion after a work was linked to all outcome measures: bodily pain, physical functioning, and
work ability.
Participation
15
The third main outcome examined in the study was perceived current and future ability to work.
Experience of LBP causes absenteeism from work and early retirement. Work ability in cases of
musculoskeletal disease is affected by several physical, psychosocial, individual-level, and
environmental factors (43). In our study, the strongest associations detected were with perceived
lumbar exertion, perceived recovery from work, depression, and FAB-W.
Managing physically demanding work and having low-back troubles is a challenging combination.
Perceived lumbar exertion after work depends on exposure to physical loads at work, the length of
the work shift, and personal physical capacities. Handling physically demanding work without
incidents of LBP probably requires sufficient physical capacities, but exact cut-off points in fitness-
test results are unknown. Therefore, further research is needed.
Personal factors
For the study reported on here, fear-avoidance beliefs were positioned in the personal factors
domain, representing one’s attitudes affecting perception of pain and of physical activity and work
ability. In previous studies, FAB has been positioned in the ‘body structures and functioning’ ICF
domain also (44).
In our study, FAB related to work was associated with all three main outcomes in a group who are
still functional but some of whom might be on the verge of losing their work ability in the coming
years. That FAB-W was related to bodily pain confirms that attitudes have an effect on pain
severity and consequences in this recurrent-LBP population. Associations with physical functioning
support the theory of deconditioning mediated by FA and kinesiophobia (45), and associations with
work ability support the idea that fear-avoidance beliefs are a sort of a cognitive failure or
dysfunction tied to specific movements only (here related to work or work tasks) (46). On the other
hand, nursing duties such as lifting and transferring patients are physically heavy and cause
seriously harmful load on the back structures. Therefore, it is no wonder that nursing personnel’s
Kommentar [KJ24]: causal? Or association?
Kommentar [KJ25]: for what?
Kommentar [KJ26]: Rephrase? ... risk for LBP? Reference.
16
attitudes to some work duties are filled with trepidation.
Fear-avoidance beliefs play a central role in chronic non-specific LBP (47). The role of FAB in
non-chronic populations remains unclear, but it seems that it is linked to the transition of pain to the
chronic stage (48) and plays a key role in recovery (40). Fear-avoidance is not, however,
unambiguously related to deconditioning, disuse, or lower physical fitness (49).
Clinical implications and conclusions
The multi-aetiology risk factors for chronic LBP pain and prolonged disability are quite well
established, but their associations in non-chronic populations are not widely documented. Both
psychosocial risk factors and physical performance levels were associated with pain, physical
functioning, and work ability in our study sample, with recurrent LBP and physically burdensome
work.
Level of perceived lumbar exertion after work was assessed with a simple question offering five
response options. This measurement showed strong associations with all three main outcomes and
the level of physical fitness. Therefore, it could be used as a screening tool in assessment of risks of
prolonged disability and possible loss of work ability. Those who perceive high exertion in their
low back after work could benefit from fitness tests and exercise counselling.
Measurement methods to screen people who have a physically demanding job and may be at risk
for LBP are needed in occupational health services. Our study’s wide range of measurements and its
results might be useful in developing measurement batteries.
The main limitation of the study is its cross-sectional design. Interpretations as to causality cannot
be made. Hence, a prospective study design is needed, to explore the associations of the factors that
appear; causal relationships; and effects on perceived pain, physical functioning, and work ability.
This understanding should aid in identifying persons at risk of LBP troubles and targeting treatment
Gelöscht: when organic pathology is not evident
Gelöscht: It seems that b
Gelöscht: are
Gelöscht: also
Gelöscht: alternatives
Gelöscht: setting
17
and interventions at the correct, identifiable problems, thereby perhaps providing possibilities for
avoiding the path to chronic pain.
In conclusion, recurrent NSLBP is a complex multi-factor phenomenon wherein individual factors
do not operate in isolation from other factors. In our study, we sought to explore which factors are
the central ones in physically demanding work. Perceived lumbar exertion in the low back after
work and work-related fear-avoidance beliefs were factors that contributed to all outcome variables:
bodily pain and pain interfering with normal work, physical functioning, and perceived work
ability. Level of physical fitness is related to perceived lumbar exertion; therefore, sufficient
physical performance capacity might be of importance for maintaining ability to work in nursing
duties.
ACKNOWLEDGEMENTS
The authors wish to thank the Social Insurance Institution of Finland and the Tampere University Hospital
for financial support for the NURSE RCT, and researchers from Finnish Institute of Occupational Health;
Sirpa Lusa, PhD, and Harri Lindholm, PhD, for contributing to the study design and measurement selection.
The authors declare no conflicts of interest
Kommentar [KJ27]: You may add questions that ’your’ RCT can answer, e.g. changing physical activity, beliefs and self rated work ability.
18
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21
Figure 1. Recruitment process for the NURSE RCT.
22
Figure 2. Measurements of LBP outcomes in the ICF framework.
23
Figure 3. Contribution of risk factors associated with three dependent variables (bodily pain and pain
interfering with normal work, physical functioning, and perceived current and future ability to work) in the
ICF model’s three domains: body structures and functions, activities, and participation.
24
Table I: Baseline characteristics of the study sample (n=219)
n (%) mean (SD) or
Md (Q1,Q3)
Age (years) 219 46.4 (6.8)
Basic education level
lower than secondary school
high school or above
87
132
(39.7)
(60.3)
Profession
nurse
nursing assistant
physiotherapist or assistant PT
midwife
radiographer or lab technician
head nurse
102
89
14
6
5
3
(46.6)
(40.6)
(6.4)
(2.7)
(2.3)
(1.4)
Number of years working 217 11.4 (8.8)
Work type
shift work
regular work
152
66
(70)
(30)
Smoking
non-smoker
smoking regularly
smoking occasionally
157
36
26
(71.7)
(16.4)
(11.9)
Hormonal status
regular periods
irregular periods
periods with hormone replacement therapy
post-menopause
91
30
11
86
(41.6)
(13.7)
(5.0)
(39.3)
Body mass index (BMI), kg/m2
normal weight (≤24.9)
overweight (25.0–29.9)
obese (≥30.0)
88
90
38
(40.7)
(41.7)
(17.6)
26.4 (4.4)
Perceived health
below average
average
good
very good
1
81
124
12
0.5
37.2
56.9
5.5
Perceived fitness in comparison to persons of the same
age and gender
much worse
somewhat worse
similar
somewhat better
much better
7
54
109
42
6
3.2
24.7
49.8
19.2
2.7
Work satisfaction
Possibilities to exert an influence on one’s work
Support from one’s supervisor
Conflicts with one’s supervisor
Work stress (Siegrist’s effort–reward model)
2.8 (0.7)
3.4 (0.8)
2.0 (1.7,2.7)
1.5 (1.3, 1.8)
LBP intensity (VAS 0–100; past 4 weeks) 218 36.2 (22.6)
Frequency of LBP
daily
most days of the week
a few days a week
recovered from low back pain episodes
23
56
82
31
12
29
43
16
Kommentar [KJ28]: Explain meaning of scores in footnote. Explain ’Siegrist model’ in text?
25
Table II: Descriptors of outcome measures and the risk factors that were analysed in line with the ICF model (n=219)
mean (SD) Md (Q1,Q3) n (%)
Outcome measurements:
Bodily pain and pain interfering with work
(RAND-36)
63.1 (19.0)
Physical functioning (RAND-36) 90 (80,95)
Self-assessed current and future ability to work 23 (21,24)
Risk factors:
Body structures and functioning:
Number of musculoskeletal pain sites 3.2 (1.3)
BMI 26.4 (4.4)
Beck Depression Inventory, 9 items (9–36 pts) 16 (13,19)
Trunk lateral flexion (cm) 18 (3.3)
Perceived recovery from work
recovering well
some difficulties
not recovering
90
102
21
(42)
(48)
(10)
Exertion in various body parts after work 12.5 (3.8)
Perceived lumbar exertion after a work shift
little exertion
exertion
high exertion
63
79
74
(29)
(37)
(34)
Tiredness and sleepiness 7 (5,10)
Activities:
Heath-related fitness
six-minute walk (walking distance, metres) 620 (49.5)
modified push-ups (repetitions) 9.1 (3.0)
one-leg squats (repetitions) 9.6 (2.5)
vertical jumps (cm) 29.1 (5.8)
running a figure of eight (seconds) 7.6 (7.1, 8.2)
Participation:
Physical activity:
Aerobic activity
meeting recommendations
not meeting recommendations
Strength training
meeting recommendations
not meeting recommendations
54
156
44
174
(26)
(74)
(20)
(80)
Personal factors:
Fear-avoidance beliefs
related to physical activity
related to work
13.1 (6.2)
10 (5,15)
Kommentar [KJ29]: Suggestion: add ’moderate’
26
Table III: Correlations between interval-scale risk factors for low back pain and outcome measures. (statistically
significant correlations are in boldface)
ICF domain Body structures and
functioning: Bodily pain
and pain interfering with
work
Activities: Physical
functioning Participation:
Work ability
Body structures and
functioning
r
p
rs
p
rs
p
Number of musculoskeletal pain
sites -0.28 <0.001 -0.29 <0.001 -0.21 0.002
BMI -0.04 0.56 -0.15 0.03 -0.15 0.03
Depression
Beck inventory, 9 itemsa
-0.079
0.37
-0.25
<0.001
0.42
<0.001
Trunk lateral flexion 0.04 0.61 0.12 0.08 0.12 0.07
Perceived exertion after work -0.39 <0.001 -0.38 <0.001 -0.45 <0.001
Tiredness and sleepinessa -0.128 0.65 -0.10 0.15 -0.25 <0.001
Activities
Heath-related fitness
six-minute-walk test 0.16 0.02 0.28 <0.001 0.19 0.005
modified push-ups 0.09 0.17 0.37 <0.001 0.32 <0.001
one-leg squats -0.01 0.86 0.28 <0.001 0.30 <0.001
vertical jumps 0.05 0.46 0.26 <0.001 0.23 <0.001
running a figure of eighta -0.10 0.15 -0.34 <0.001 0.33 <0.001
Personal factors
FAB about physical activity -0.26 <0.001 -0.15 0.03 -0.23 0.01
FAB about worka -0.25 <0.001 -0.25 <0.001 -0.38 <0.001
r = Pearson’s correlation coefficient, rs = Spearman’s rank correlation coefficient, a = skewed distribution where rs is
used to describe the correlation, BMI = body mass index, and FAB = fear-avoidance beliefs.
Kommentar [KJ30]: Table also includes variables you use as confounders used for adjustment..
27 Table IV: Associations between risk factors for low back pain in various ICF domains: (a) body structures and functioning and (b) the participation domain, all categorical
variables and outcome variables, for (1) bodily pain and pain interfering with normal work, (2) physical functioning, and (3) perceived current and future ability to work
(statistically significant p-values are in boldface)
Body structures and
functioning:
Bodily pain
Activities:
Physical functioning Participation:
Perceived current and
future ability to work
Body structures and functioning
domain:
n
mean (SD)
p
Md (min.,
max.)
p
Md (min.,
max.)
p
Perceived lumbar exertion after
work
little exertion
exertion
high exertion
63
79
74
70.4 (18.8)
66.3 (17.4)
53.0 (17.0)
<0.001
95 (60, 100)
90 (15, 100)
80 (45, 100)
<0.001
24 (15, 27)
23 (16, 26)
21 (12, 27)
<0.001
Perceived recovery from work
recovering well
some difficulties
not recovering
90
102
21
65.4 (18.8)
62.9 (18.7)
57.3 (18.1)
0.19
90 (60, 100)
85 (15, 100)
75 (50, 100)
0.003
23 (17, 27)
22 (15, 26)
21 (16, 27)
<0.001
Participation domain
Physical activity
Aerobic activity
meeting recommendations
not meeting recommendations
Strength training
meeting recommendations
not meeting recommendations
54
156
44
174
63.0 (19.9)
63.4 (15.9)
62.6 (18.5)
63.6 (20.7)
0.89
0.76
Md (Q1, Q3)
93 (85, 95)
85 (75, 95)
95 (85, 95)
85 (75, 95)
0.05
0.02
Md (Q1, Q3)
23 (21, 24)
23 (20, 24)
23 (21, 25)
22.5 (20, 24)
0.87
0.053
28
Table V: Associations between risk factors for LBP and outcome measures (bodily pain and pain interfering with normal work, physical functioning, and perceived current
and future ability to work) with a statistically significant association in bivariate analysis, analysed via generalised linear models
Bodily pain and pain interfering with work Physical functioning Perceived current and future work ability
Crude β (p) Adjusteda β
(p)
Adjustedb β
(p)c
Crude β (p) Adjusteda β
(p)
Adjustedb β
(p)d
Crude β (p) Adjusteda β
(p)
Adjustedb β
(p)
Body structures
and functioning:
Number of
musculoskeletal
pain sites
-3.06
(<0.001)
-2.65
(0.002)
-2.78
(0.002)
-0.28 (<0.001) -0.27
(<0.001)
-0.025 (0.001)
Perceived lumbar
exertion
-13.95
(<0.001)
-15.31
(<0.001)
-15.83
(<0.001)
-0.075 (0.005) -0.08 (0.005) -0.079 (0.003) -0.052 (0.003) -0.055
(0.003)
-0.06 (0.003)
Depression -0.003 (0.045) -0.003 (0.08) -0.003 (0.08)
Recovery from
work
-0.03 (0.03) -0.052 (0.04) -0.04 (0.02)
Activities:
Modified push-ups 0.008 (0.045) 0.007 (0.08) 0.007 (0.09)
Running a figure of
eight
-0.033 (0.01) -0.033 (0.03) -0.037 (0.01)
Personal factors:
FAB-W -0.44
(0.02)
-0.59
(0.002)
-0.61
(0.002)
-0.004 (0.01) -0.004
(0.003)
-0.004 (0.003) -0.004
(<0.001)
-0.004
(<0.001)
Β = regression coefficient; FAB-W = fear-avoidance beliefs related to work; a = adjusted for age, BMI, and work type (shift work vs. regular work);
b = adjusted for age, BMI,
work type (shift work vs. regular work), hormonal status, and work satisfaction; and LBP = low back pain.
29 Table VI: Associations between fitness-test results and perceived exertion in the low back after a work shift, analysed via ANOVA and adjusted for age (p-values reflecting
statistically significant differences are in boldface)
Mean (SD) test results for various categories of perceived lumbar exertion
after a work shift
Fitness test: little exertion exertion high exertion mean difference from
little exertion to high
exertion (95% CI)
p-value
six-minute-walk test (m) 632.1 (49.7) 620.7 (44.8) 602.6 (51.1) 29.5 (9.5, 49.6) 0.001
modified push-ups (reps) 10.2 (3.2) 8.8 (2.5) 8.1 (3.2) 2.1 (0.8, 3.3) <0.001
one-leg squats (reps) 10.2 (2.3) 9.7 (2.3) 8.7 (2.9) 1.5 (0.5, 2.5) 0.001
vertical jumps (cm) 30.1 (5.5) 29.3 (5.5) 27.5 (6.3) 2.7 (0.2, 5.1) 0.03
running a figure of eight (s) 7.6 (0.9) 7.7 (0.8) 8.1 (1.2) -0.5 (-0.9, -0.1) 0.007
SD = standard deviation and CI = confidence interval.