Article
Health status, work limitations, and
return-to-work trajectories in
injured workers with musculoskeletal disorders
Ute
Bültmann, Renée-Louise Franche, Sheilah Hogg-Johnson, Pierre
Côté, Hyunmi Lee, Colette Severin, Marjan Vidmar, Nancy Carnide Received:
(Note: Figures from this article have been removed for ease of transfer. Please refer to interpretations in the article's text for detailed information regarding study data)
Abstract
Background
The
purpose of this study was to describe the health status and work limitations in
injured workers with musculoskeletal disorders at 1 month post-injury,
stratified by return-to-work status, and to document their return-to work trajectories
6 months post-injury.
Methods
A
sample of 632 workers with a back or upper extremity musculoskeletal disorder,
who filed a Workplace Safety
and Insurance Board lost-time claim injury, participated in this prospective
study. Participants were assessed
at baseline (1 month post-injury) and at 6 months follow-up.
Results
One
month post-injury, poor physical health, high levels of depressive symptoms and
high work limitations are
prevalent in workers, including in those with a sustained first return to work.
Workers with a sustained first
return to work report a better health status and fewer work limitations than
those who experienced a recurrence of work absence or who never returned to
work. Six months post-injury, the rate of recurrence of work absence in the
trajectories of injured workers who have made at least one return to work
attempt is high (38%), including the rate for workers with an initial sustained
first return to work (27%).
Conclusions
There
are return-to-work status specific health outcomes in injured workers. A
sustained first return to work is not equivalent to a complete recovery from
musculoskeletal disorders.
Introduction
Work-related
musculoskeletal (
Recently,
Pransky et al. [7] pointed out that ‘‘despite an abundance of RTW research, the
concept of RTW is often poorly defined, and there is not substantial agreement
about what constitutes a successful RTW outcome.’’ Many studies have been
focused on (first) return to work as the primary outcome measure, e.g., return
to work is used as an indicator for a reduction in disability—usually with the assumption
that workers who return to work are completely recovered from the disabling effects
of the injury [10]. However, several studies have demonstrated that workers who
return to work are not fully recovered from their initial complaints or injury
[10–15]. The traditional outcome measures of return to work and time lost from
work do not capture important information about the burden of injury that can
be shown by self-reported measures of disability and functional limitations.
Hence, to obtain a complete picture of the complex RTW process, capturing the recurrences
of work absence, the persistence of disability, and their consequences for work
performance, it is important to use multiple outcome measures during follow-up.
Although
a few studies have addressed health outcomes, such as pain, functional status,
and general health, in
relation to RTW status [11, 12, 14], little is known about depressive symptoms,
which have been suggested to increase the total numbers of days on benefit [16]
and about limitations at work in injured workers. Furthermore, it is largely
unclear how injured workers ‘‘transit’’ in their RTW status over time. So far,
we do know that a substantial proportion of workers with cumulative trauma disorders
of the upper extremity [15] and compensated back pain (Côté et
al., submitted) experience multiple episodes of work absence.
The
purpose of this study was to describe the health status, assessed by multiple
outcome measures, and work limitations, in injured workers with
Materials and methods
Study design
The
present study was conducted within the sampling frame of a prospective study of
Participant recruitment and final
study sample
Study
eligibility required participants to have a new, accepted or pending, back or
UE
A
total of 632 participants completed the baseline interview 1 month post-injury.
The overall response rate was
61% (632 out of 1,038 eligible and contacted potential participants). Verbal
consent for the interview data was obtained from all participants. The mean
time between the date of injury and the date of interview was 29.6 days (SD
6.2; median 29 days, range 15–46 days). Approximately 98% of the participants
were interviewed within 6 weeks post-injury. For the linkage with WSIB data,
written consent was obtained from 479 participants, for which WSIB wage
replacement data was available for 431 participants. A consent-to-linkage
analysis showed that consenters (n =
479) and non-consenters were similar in terms of sociodemographic,
workplace, health status, and work absence variables. However, consenters were
more likely to have a higher level of education, and male consenters were more
likely to be older than male non-consenters (Franche et al., submitted).
Definition of the RTW status
At
baseline, four mutually exclusive RTW status groups were constructed, based on
the workers’ responses to the following yes/no questions: ‘‘Have you gone back
to work at any point since your injury (includes part-time or modified work)?’’
and ‘‘Are you currently working at any job right now?’’ The four groups were:
(1) sustained first return to work (RTW-S),
(2) return to work with recurrence(s) of work absence and working at time of
interview (RTW-R working), (3) return to
work with recurrence(s) of work absence and not working at time of interview (RTW-R
not working), and (4) no return to work (No
RTW). In the analyses,
we collapsed the two return to work with recurrence(s) groups into one group (RTW-R).
RTW status was assessed at each follow-up.
Measurements: health outcomes and
work limitations
Pain intensity
We
used two items from the Von Korff Pain Scale [17, 18] to measure pain
intensity. On a 10-point numerical rating scale (0 = ‘‘no pain’’ to 10 = ‘‘pain
as bad as could be’’), participants were asked to indicate their level of
perceived pain from their workplace injury (1) at the present
time and (2) on average in the past month.
Functional status
Functional
disability associated with back pain was measured using the Roland–Morris
Disability Questionnaire [19], a 24-item questionnaire assessing the presence
of activity limitations. Responses to individual items (yes/no) are summed up
and range from 0 (no disability) to 24 (severe disability). The score is
averaged and—for a better comparison with scores of other
instruments—transformed to a standardized score of 0–100 (by multiplying each averaged
score by 100), with a higher score indicating greater
disability. The Roland–Morris has been shown to have good psychometric
properties [20–25]. In the baseline sample, the internal consistency (Cronbachs
a) was 0.92.
The
11-item QuickDASH was used to assess physical function and symptoms in
participants with
When
participants reported pain in both the back and UE, they completed both the Roland–Morris
and the QuickDASH.
For these participants, scores from each instrument were converted into a z-score
and the highest z-score was used as the
index of functional status. For participants completing only one measure of
functional status, the z-score of that measure
was used as the index of functional status. In addition, for those completing
both measures, determination of the main pain site, i.e., back or UE, was based
on the highest z-score on the
Roland–Morris or the QuickDASH.
General health
The
Short Form-12 (SF-12), a 12-item version of the SF- 36, was used to measure
physical (Physical Component Summary Scale Score;
Depressive symptoms
The
20-item Center for Epidemiologic Studies Depression (CES-D) [31] scale was used
to measure depressive symptoms. The items report the frequency of occurrence of
symptoms in the past week on a 4-point rating scale
ranging from ‘‘rarely or none of the time’’ (<1 day) to ‘‘most of the time’’
(5–7 days). The score ranges from 0 to 60 with a higher score denoting more
depressive symptoms. CES -D scores ‡16
are indicative of individuals at risk for clinical depression [31]. The
internal consistency was 0.92, measured in the baseline sample.
Work limitations
We
used the 16-item version of the Work Limitations Questionnaire (WLQ-16) to
assess limitations at work due to injury or associated treatment [32–35]. The
WLQ-16 covers four domains: output demands (4 items), mental demands (6 items),
physical demands (4 items), and time management demands (2 items). Items are
scored on a 5-point scale, ranging from ‘‘none of the time’’ to ‘‘all of the time.’’
The scores on the individual items are summed, averaged, and transformed to a
standardized score of 0–100, with a higher score indicative of more
limitations. The internal consistency Cronbachs a’s
were 0.82 (output demands), 0.86
(mental demands), 0.78 (physical demands), and 0.76 (time management demands)
at baseline.
Sociodemographics, days off work,
and comorbidity
Participants
provided information on age, gender, education, living status, number of children
under the age of 18, and personal income. Information on occupational status was
obtained from the WSIB database. One self-reported question assessed how many
full days of work a participant had missed due to the injury. In addition, data
on time receiving wage replacement benefits was obtained from the WSIB
database. The Saskatchewan Comorbidity Scale was used to measure comorbidity
(Jaroszynski et al., unpublished work). The 16/14-item (women/men) self-report scale
assesses the presence and severity of health problems.
Participants
are instructed to indicate whether they currently have a particular health
problem/disease and, if so how much it has affected their health in the last 6
months. The response options range from 1 = ‘‘not at all’’ to 4 = ‘‘severe.’’
In the present study, two additional items pertaining to gynecological problems
and pregnancy status were added for women. Responses were combined and categorized
as: no comorbidity, comorbidity with no/mild effect on health, and comorbidity
with moderate/severe effect on health.
Statistical analyses
Univariate
statistics (means, standard deviations, frequency counts) were used to describe
participants, for the total cohort and by RTW status, in terms of their
baseline sociodemographics, health outcomes, and work limitations. Differences
in baseline characteristics between the three RTW status groups (RTW-S, RTW-R,
and No RTW) were tested using a v2 test
or analysis of variance. Multiple comparisons, with RTW-S as reference group,
were performed with a Tukey correction. Group differences in health outcomes and
work limitations, adjusted for identified covariates were tested with
Results
Baseline characteristics and
selection bias analysis
A
total of 632 participants, 350 (55%) men and 282 (45%) women, completed the
baseline interview 1 month postinjury. Table 1 shows the sociodemographic
factors for the total sample and by RTW status at baseline. The mean age of the
total cohort was 42.2 years (SD 10.8) and
approximately 69% lived with a partner. The mean duration of time receiving
wage replacement benefits, based on WSIB data, was 19.1 days (SD
8.9; median 20 days). Sixty-six percent of the participants were
primarily experiencing back pain and 34% UE pain.
To
examine a possible selection bias, we compared the cohort participants (n
= 632) to a group of algorithm-selected potential participants (n
= 3,712) on characteristics extracted from the WSIB database, where
the algorithm mimicked the inclusion criteria of our study.1 The time frame during
which their injury occurred was the same as for our study sample. This analysis
showed that participants were comparable to potential participants with regards
to firm size, industrial sector, and income level (Table 2). However,
participants were more likely to be older and female. Women aged 40–49 were
more likely to participate than women in the other age categories, and older
men were more likely to participate than younger men.
With respect to claim status, we compared only participants with accepted
claims and available wage replacement
data (n = 559) with potential participants, since this
data is not available for participants with pending, denied or abandoned
claims. Participants were more likely to have a longer duration on wage
replacement benefits at 1 and 6 months post-injury and a higher rate of wage
replacement re-instatement at 6 months post-injury than potential participants,
suggestive of more severe work disability in our cohort.
Group differences in baseline
characteristics
A
total of 625 participants were categorized into one of the four RTW status
groups. The remaining seven participants were working when interviewed at
baseline, but not asked about recurrence(s) due to an error in a skip pattern
of the questionnaire, which was subsequently corrected. At baseline
(approximately 1 month post-injury), 47% of the participants reported a
sustained first return to work, 5% a return to work with recurrence(s) of work
absence and working at time of interview, almost 9% a return to work with
recurrence(s) of work absence and not working at time of interview, and 39% no
return to work.
With
regards to gender, age, children under age 18, education, occupational status,
and working hours per week at the time of the injury no statistically
significant differences were observed across the three RTW groups. However, participants
who had a sustained first return to work reported more often that they lived
with a partner (v2 =
11.0, p = .004) and reported a higher personal income (v2 =
11.7, p = .069) than those with a recurrence or no
return to work. These variables were used as covariates in subsequent analyses.
With
respect to the mean duration of time receiving wage replacement benefits, based
on WSIB data, significant differences were observed across all three RTW groups
(F = 122.6, p =
.000). Significant differences were also seen with self-reported full days off
work due to the injury (F = 169.7, p
= .0000). With respect to pain site, a statistically significant
difference was found across the RTW groups: participants with a sustained first
return to work and those who experienced a recurrence reported low back
pain more often, and participants who did not return to work reported pain in
the UE more often (v2 =
21.6, p = <.0001). A total of 81% of the participants
reported no comorbidity, whereas 5% reported no/mild effects on health, and 14%
reported moderate/severe effects on health, with no statistically significant
group differences.
Group differences in health outcomes
and work limitations
Table
3 presents the adjusted (for age, gender, living status, and income level)
estimated means for baseline health outcomes and work limitations by RTW
status, with multiple comparison results. Participants with a sustained first return
to work reported significantly less pain compared to those with a recurrence
and no return to work. Moreover, they also reported significantly less pain in
the past month compared to those with no return to work. In participants with
back pain, those with a sustained first return to work reported significantly
less functional disability compared to those with a recurrence and no return to
work. In participants with UE pain, we observed that those with a sustained first
return to work reported significantly less functional disability compared to
those who did not return to work, but not compared to those who experienced a recurrence.
With regards to physical and mental health as well as depressive symptoms,
participants with a sustained first return to work reported significantly
better health and fewer depressive symptoms than those with a recurrence and no
return to work. It is interesting to note that high levels
of depressive symptomatology, indicative of being at risk for clinical
depression, were found in all participants, especially in those with a
recurrence and those who did not return to work. For all outcomes, there were
no significant differences between participants who experienced a recurrence
and those who did not return to work. With regards to limitations at work,
those with a sustained first return to work and those with a recurrence,
reported limitations in all domains, but mainly for physical demands and time
management demands. As expected, participants with a sustained first return to
work reported significantly fewer limitations than those with a recurrence.
Attrition analysis
Six
months after injury, the 632 participants who had completed the baseline
interview were approached again to complete the follow-up interview. Overall,
446 participants, 238 (53%) men and 208 (47%) women, completed the follow-up
interview (retention rate of 70.6%). Reasons for non-response in the follow-up
interview were ‘‘unable to contact’’ (n =
92), ‘‘avoided contact’’ (n = 49), and ‘‘refused
to participate’’ (n = 45). An attrition
analysis, comparing respondents (n =
446) of the 6-month interview with
non-respondents (n = 186), revealed that
nonrespondents were more likely to be younger, to work longer hours at the time
of injury, and to specify ‘‘back’’ as their primary pain site. Moreover, male
non-respondents tended to be younger than male respondents, whereas in females differences
in age were not statistically significant. Otherwise, non-respondents did not
differ significantly with respect to other sociodemographic, workplace, health status,
and work absence variables tested, including time receiving wage
replacement benefits, re-instatement of wage replacement benefits 6 month
post-injury, self-reported work
absence duration 1 month post-injury, and claim status. Full details of the attrition
bias analysis have been reported elsewhere (Franche et al., submitted).
RTW
trajectories from baseline to 6 month follow-up (Figure 2) shows the
RTW trajectories for 439 participants, based on self-reported RTW
status at baseline and 6 month follow-up. The majority (73%) of workers
with a
sustained first return to work at baseline were still at work 6 months
later.
However, 27% had experienced at least one recurrence during that time
period.
All participants who experienced a recurrence remained, by definition,
in this
group. Of those participants who had not returned to work at baseline,
59% had
a sustained first return to work 6 months later,
17% had made a RTW attempt with a recurrence, and 24% were still off
work 6
months post-injury. Six months post-injury, the rate of recurrences of
work
absence in workers who had made at least one RTW attempt was 38% [n
= 153 recurrences/(n = 439 minus n
= 40 with no RTW attempt)].
Discussion
The
findings of this cohort study suggest the presence of a pattern in baseline
health states and work limitations specific to RTW status, 1 month post-injury.
Workers with a sustained first return to work reported less pain, less functional
disability, better physical and mental health, fewer depressive symptoms, and
fewer work limitations compared to those who experienced a recurrence of work absence
or who never returned to work. The study adds to the literature by
demonstrating that depressive symptoms and limitations at work are prevalent in
workers 1 month post-injury, including in those with a sustained first return to
work. A substantial rate of recurrences of work absence over 6 months was found
(38%), even in workers who had initially made a sustained first return to work
at baseline (27%). Moreover, of those workers who did not return to work at
baseline, 17% attempted to return and experienced a recurrence within 6 months
of the injury, and 24% were still off work at 6 months post-injury.
Our
findings are consistent with previous research suggesting that a return to work
does not translate into a complete
recovery from a
When
interpreting the results, the following methodological issues must be
considered. Though reasonable for a study among claimants, the overall
participation rate of 61% raises the question of selective participation, which
may have biased the results. However, the cohort was shown to be representative
of the most comparable claimant group with regards to basic demographic and workplace
variables, but not with regards to duration of time receiving wage replacement
benefits and rates of wage replacement re-instatement, suggesting the presence
of more severe disability in the cohort. Hence, the generalizability of
the results remains limited with respect to workers with less severe work
disability. More importantly, the
rates of self-reported recurrence of work absence may be inflated in our
cohort.
A
related issue concerns the loss-to-follow-up of 29%. The attrition analysis
demonstrated that non-respondents and respondents were similar with regards to
time receiving wage replacement benefits, the occurrence of re-instatement of
wage replacement benefits, and self-reported work absence duration.
Non-respondents were younger males, worked longer hours, and were more likely
to specify ‘‘back’’ as their primary pain site compared to respondents.
Future
research should further explore the relationship between recurrence(s) of work
absence, health outcomes, and work limitations over an extended period of time.
We found that workers who experienced a recurrence after a first return to work
clearly report more health problems and work limitations than those with a
sustained first return to work, and their health status is often comparable to
workers who do not return to work. Our trajectory analyses were based on a 6
months time window and it was not yet possible
to examine multiple recurrences and their effects on health outcomes and work
limitations over a longer period of time. However, 12 month follow-up data will
make such analyses possible in the future. Moreover, we have to examine
important and meaningful changes in health outcomes and work limitations
between baseline and follow-up across the possible RTW trajectories [39], and also
study them in relation to a broad range of factors (e.g., RTW interventions,
disability management strategies) that might have influenced the RTW process
and the outcomes considered. Finally, future research should identify early prognostic
factors of the trajectories, particularly focusing on the ‘‘problematic’’
trajectories (recurrences and persistent work absence), so that guidance for an
optimal reintegration or for recurrence prevention can be provided.
To
conclude, the results of this prospective study suggest that workers who had a
sustained first return to work report a better health status and fewer work
limitations than those who experienced a recurrence after a first return to work
or who did not return to work. However, it is also demonstrated that a return
to work is not equivalent to a complete recovery from
Acknowledgements
This
project was funded by a research grant provided by the Workplace Safety and
Insurance Board (
References
1.
Health
2.
Cassidy, J. D., Coˆte´, P., Carroll, L. J., & Kristman, V. (2005). Incidence
and course of low back pain episodes in the general population. Spine,
30, 2817–2823.
3.
Wasiak, R., Verma, S., Pransky, G., & Webster, B. (2004). Risk factors for
recurrent episodes of care and work disability: Case of low back pain. Journal
of Occupational and Environmental Medicine, 46, 68–76.
4.
Hestbaek, L., Leboeuf-Yde, C., Engberg, M., Lauritzen, T., Bruun, N. H., &
Manniche, C. (2003). The course of low back
pain
in a general population. Results from a 5-year prospective study. Journal
of Manipulative and Physiological Therapeutics,
26,
213–219.
5.
Picavet, H. S., & Schouten, J. S. (2003). Musculoskeletal pain in the
6.
Croft, P. R., Macfarlane, G. J., Papageorgiou, A. C., Thomas, E., & Silman,
A. J. (1998). Outcome of low back pain in general practice: A prospective
study. British Medical Journal, 316, 1356–1359.
7.
Pransky, G., Gatchel, R., Linton, S. J., & Loisel, P. (2005). Improving
return to work research. Journal of Occupational
Rehabilitation,
15, 453–457.
8.
Frank, J., Sinclair, S., Hogg-Johnson, S., Shannon, H., Bombardier, C., Beaton,
D., & Cole, D. (1998). Preventing disability
from
work-related low-back pain. New evidence gives new hope if we can just get all
the players onside. Canadian Medical
Association
Journal, 158, 1625–1631.
9.
10.
Baldwin, M. L., Johnson, W. G., &
11.
Lo¨ tters, F., Hogg-Johnson, S., & Burdorf, A. (2005). Health status, its
perceptions, and effect on return to work and recurrent sick leave. Spine,
30, 1086–1092.
12.
Lo¨ tters, F., Meerding, W. J., & Burdorf, A. (2005). Reduced productivity
after sickness absence due to musculoskeletal disorders and its relation to
health outcomes. Scandinavian Journal of Work, Environment and
Health, 31, 367–374.
13.
Pransky, G., Benjamin, K., Hill-Fotouhi, C., Fletcher, K. E., Himmelstein, J.,
& Katz, J. N. (2002). Work-related outcomes in occupational low back pain:
A multidimensional analysis. Spine, 27,
864–870.
14.
Evanoff, B., Abedin, S., Grayson, D., Dale, A. M., Wolf, L., & Bohr, P.
(2002). Is disability underreported following work injury? Journal
of Occupational Rehabilitation, 12, 139–150.
15.
Baldwin, M. L., & Butler, R. J. (2006). Upper extremity disorders in the
workplace: Costs and outcomes beyond the first return to work. Journal
of Occupational Rehabilitation, 16, 296–316.
16.
Lo¨ tters F., Franche, R. L., Hogg-Johnson, S., Burdorf, A., & Pole, J. D.
(2006). The prognostic value of depressive symptoms, fearavoidance, and
self-efficacy for duration of lost-time benefits in workers with
musculoskeletal disorders. Occupational and Environmental
Medicine, 63, 794–801.
17.
VonKorff, M., Ormel, J., Keefe, F. J., & Dworkin, S. F. (1992). Grading the
severity of chronic pain. Pain, 50, 133–149.
18.
VonKorff, M., Jensen, M. P., & Karoly, P. (2000). Assessing global pain
severity by self-report in clinical and health services research. Spine,
25, 3140–3151.
19.
Roland, M., & Morris, R. (1983). A study of the natural history of back
pain. Part I: Development of a reliable and sensitive measure of disability in
low-back pain. Spine, 8, 141–144.
20.
Leclaire, R., Blier, F., Fortin L., & Proulx R. (1997). A cross sectional study
comparing the Oswestry and Roland–Morris
Functional
Disability scales in two populations of patients with low back pain of
different levels of severity. Spine, 22,
68–71.
21.
Deyo, R. A. (1986). Comparative validity of the sickness impact profile and
shorter scales for functional assessment in low-back pain. Spine,
11, 951–954.
22.
Hsieh, C. Y., Phillips, R. B., Adams, A. H., & Pope, M. H. (1992).
Functional outcomes of low back pain: Comparison of
four
treatment groups in a randomized controlled trial. Journal
of Manipulative and Physiological Therapeutics, 15,
4–9.
23.
Kopec, J. A., & Esdaile, J. M. (1995). Functional disability scales for
back pain. Spine, 20, 1943–1949.
24.
25.
Beurskens, A. J., de Vet, H. C., & Koke, A. J. (1996). Responsiveness of
functional status in low back pain: A comparison of different instruments. Pain,
65, 71–76.
26.
Beaton, D. E., Wright, J. G., Katz, J. N., The Upper Extremity Collaborative
Group (2005). Development of the QuickDASH: Comparison of three item-reduction
approaches. The Journal of Bone & Joint Surgery
American Volume, 87, 1038–1046.
27. Hudak, P. L., Amadio, P. C., &
Bombardier, C. (1996). Development of an upper extremity outcome
measure: The DASH
(disabilities
of the arm, shoulder and hand). The Upper Extremity Collaborative Group (UECG).
American Journal of Industrial Medicine, 29,
602–608.
28.
Ware, J. Jr., Kosinski, M., & Keller, S. D. (1996). A 12-Item Short-Form
Health Survey: Construction of scales and preliminary tests of reliability and
validity. Medical Care, 34, 220–233.
29.
Ware, J. Jr., Kosinski, M., & Keller, S. D. (2002). SF-12:
How to score the SF-12 Physical and Mental Health Summary scales.
30.
Luo, X.,
31.
Radloff, L. S. (1977). The CES-D Scale: A self-report depression scale for
research in the general population. Applied Psychological Measurement,
1, 385–401.
32.
Lerner, D., Amick, B. C.
33.
Lerner, D., Amick, B. C.
34.
Lerner, D., Adler, D. A., Chang, H., Berndt, E. R., Irish, J. T., Lapitsky, L.,
Hood, M. Y., Reed, J., & Rogers, W. H. (2004). The clinical and
occupational correlates of work productivity loss among employed patients with
depression. Journal of Occupational and Environmental
Medicine, 46, S46–S55.
35.
Beaton, D. E., & Kennedy, C. A. (2005). Beyond return to work: Testing a
measure of at-work disability in workers with musculoskeletal pain. Quality
of Life Research, 14, 1869–1879.
36.
37.
Dersh, J., Gatchel, R. J., Polatin, P., & Mayer T. (2002). Prevalence of
psychiatric disorders in patients with chronic work-related musculoskeletal
pain disability. Journal of Occupational and Environmental
Medicine, 44, 459–468.
38.
Keogh, J. P., Nuwayhid,