Accepted Manuscript Title: The health status of people claiming compensation for musculoskeletal injuries following road traffic crashes is not altered by an early intervention program: A comparative study Author: S.M. Littleton D.C. Hughes B. Gopinath B.J. Robinson S.J. Poustie P.N. Smith I.D. Cameron PII: DOI: Reference:

S0020-1383(14)00250-2 http://dx.doi.org/doi:10.1016/j.injury.2014.05.011 JINJ 5742

To appear in:

Injury, Int. J. Care Injured

Received date: Revised date: Accepted date:

8-2-2014 7-5-2014 11-5-2014

Please cite this article as: Littleton SM, Hughes DC, Gopinath B, Robinson BJ, Poustie SJ, Smith PN, Cameron ID, The health status of people claiming compensation for musculoskeletal injuries following road traffic crashes is not altered by an early intervention program: A comparative study, Injury (2014), http://dx.doi.org/10.1016/j.injury.2014.05.011 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

The health status of people claiming compensation for musculoskeletal injuries following road traffic crashes is not altered by an early intervention program: A

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comparative study

S.M. Littleton a,*, D.C. Hughes a, B. Gopinath b, B.J. Robinson a, S.J. Poustie a, P.N. Smith a, , I.D. Cameron b

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College of Medicine, Biology and Environment, Australian National University, Australia

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Rehabilitation Studies Unit, Sydney Medical School, University of Sydney, Australia

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Trauma and Orthopaedic Research Unit, Canberra Hospital, Australia

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Corresponding Author:

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Susannah M Littleton

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Trauma and Orthopaedic Research Unit Building 6, Level 1, Canberra Hospital

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PO Box 11, WODEN ACT 2606, Australia Tel: +61 2 6174 5143

Fax: +61 2 6205 2157

Email: [email protected]

Keywords: traffic, accident, early intervention, health status, soft tissue injury, compensation

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The health status of people claiming compensation for musculoskeletal injuries following road traffic crashes is not altered by an early intervention program: A

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comparative study

Abstract

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Objective: To compare health outcomes among claimants compared to those who were

ineligible or choose not to lodge a compensation claim. We also evaluated the effect of an

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early intervention program on the health outcomes of the participants.

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Design: Prospective comparative study using sequential cohorts.

Subjects: People presenting to hospital emergency departments with mild to moderate

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musculoskeletal injuries following road traffic crashes.

Intervention: referral to an early intervention program for assessment by musculoskeletal

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early activity.

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physician, pain management education, promotion of self-management and encouragement of

Main outcomes: The 36-Item Short-Form Survey (SF-36); Hospital Anxiety and Depression

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Scale (HADS) and Functional Rating Index (FRI) scores were assessed at post-crash and at 12 months.

Results: At 12 months, mean scores in six and five of the SF-36 domains were significantly lower among participants who claimed compensation versus those who chose not to claim or were ineligible, respectively. Differences in mean SF-36 scores ranged from 3.0 (‘general health perception’) to 8.0 units ('role limitations due to physical problems'). Participants who claimed compensation had 6.3- and 4.6-units lower SF-36 physical component score compared to those who were ineligible (p=0.001) or chose not to claim (p=0.01), respectively. Participants who claimed compensation reported a worse HADS–depression score of 6.46 versus 4.97 and 4.69 observed in those who were ineligible (p=0.04) or did not

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claim (p=0.01). Claimants had worse FRI scores compared to non-claimants (p=0.01) and those who were ineligible (p=0.01). The early intervention did not improve health outcomes, 12 months after injury.

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Conclusions: Claiming compensation was associated with a worse health status for people with soft tissue injuries caused by road traffic crashes. The health status in people claiming

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compensation was not altered by an early intervention program.

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Introduction The process of recovery from whiplash injuries caused by road traffic crashes is variably described in the literature as being rapid and complete,1-3 to being protracted with symptoms

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persisting for several years.4, 5 There are a number of factors that influence the recovery process, for example, depression and anxiety,6, 7 female gender,8, 9 high initial pain intensity and involvement in the compensation claims process.9, 12

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In a previous study,13 we demonstrated that people who claimed compensation had a

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worse health status 12 months after sustaining mild to moderate musculoskeletal injuries in a road traffic crash compared with people who do not claim compensation. Prolonged exposure

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to the compensation claims system and involvement of a lawyer 14, 15 during the claims

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process are two components of the compensation claims process that can negatively influence outcome. Psychological stressors such as anxiety related to the claims process are thought to

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prolong symptoms and result in a pain pattern, that once established, does not resolve with

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claim settlement.16 Addressing these stressors with an early intervention program may assist in the recovery of those individuals who claim compensation.

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A number of studies have found that participation in an early, active treatment program

that aims to increase mobilisation, reduce fear of movement and improve patient expectation, can result in reduced pain perception; reduced disability associated with pain; and improved self-efficacy.17-20 From this we can hypothesise that exposure to an early active treatment program may counteract some of the negative factors affecting outcome that exposure to the compensation system exacerbates.

The findings of our previous study 13 were based on the health outcomes of the control arm of the Accident Care Evaluation (ACE) study which was initiated in the Australian Capital Territory (ACT) to improve the health status of people with minor injuries sustained in road traffic crashes. We now expand on the results of our previous study to include a

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second group of subjects who participated in an early intervention program. The present report aims to: 1) Establish whether there are differences in various health outcome measures (i.e. quality of life, anxiety, depression and disability) between participants who claimed

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compensation compared to those who were eligible and chose not to claim compensation or those who were ineligible to claim as they are judged to be “at fault” in the motor vehicle

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crash; and 2) Assess the effects of an early intervention program on the long-term health

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status of participants 12 months after the crash.

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Methods Study design and population

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The methods for this study have been published previously.13 Briefly, the ACE study was a prospective, sequential cohort intervention study in which patients who presented to the

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emergency department (ED) with mild to moderate musculoskeletal injuries (Injury Severity

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Score < 15) sustained in a motor vehicle or motorcycle crash that had occurred within seven days prior to presenting to the ED, who were aged between 18 and 70 years, and were usually

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resident in the ACT were recruited. Patients were excluded if they had sustained a head injury; spinal fracture or cord injury; required admission to hospital for more than three days; were from a non-English speaking background; did not wait to be seen for treatment; were pedestrians; or were pregnant. Human Research Ethics Committee approval was granted by the Australian National University, The Canberra Hospital, Calvary Public Hospital and the University of Sydney.

Demographic and crash related data All recruited participants completed a questionnaire providing socio-demographic, injury (e.g. location and number of injury sites) and crash related information. Employment was

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defined as being in full-time or part-time paid work. Students who performed some type of paid part-time work were included in this group. Tertiary qualifications were defined as completion of a tertiary degree or Technical and Further Education (TAFE) or college

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education. Marital status included the following groups: single; married/ defacto; or separated/ divorced/ widow. Details on living arrangements were obtained and classified as:

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lives alone; lives with spouse and/ or family; or lives with flatmate.

Injuries were assigned an Abbreviated Injury Score (AIS) 21 from which an Injury

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Severity Score (ISS) 22 was derived. The ISS is calculated by adding the squares of each of

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the three most severely injured body regions. ISS was categorised into minor injury (ISS 1-3)

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and moderate (ISS >4).

Health status measures

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Health measures were assessed post-crash, reflecting the baseline post-injury status, and at

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six months and 12 months. Participants were asked to describe their general health status post-crash, using a 5-point Likert scale (excellent, very good, good, fair, or poor). The 36-

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Item Short-Form Survey (SF-36) contains 36 items, which produces eight subscale scores representing dimensions of health and well-being.23 The eight subscales are “physical functioning,” “role limitations due to physical problems,” “bodily pain,” “general health perceptions,” “vitality,” “social functioning,” “role limitations due to emotional problems,” and “mental health.” The subscales are then summarized as a physical and mental component score (i.e. PCS and MCS), calculated by assigning relative weights to each subscale as described by the developers of this instrument and compared with Australian population norms.24 The domain scores are rated so that higher values indicate better health (range 0100).23

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Hospital Anxiety and Depression Scale (HADS) is a 14-item scale with 2 sub-scales; one for measuring depression and one for anxiety. Each item has a four level response (scored 0-3). Scores are summed separately and total scores for each component are derived

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where 0-7 represents normal levels of anxiety or depression, 8-10 represents mild anxiety or depression, 11-14 represents moderate anxiety or depression and 15-21 represents severe

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anxiety or depression.25 Functional rating index (FRI) combines concepts of the Oswestry Low Back Disability Questionnaire and the Neck Disability Index. The 10 items measure

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both pain and function of the spinal musculoskeletal system26. Items use a 5-point scale

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ranging from “0” = no pain or full ability to function, to “4” = worst possible pain and/or unable to perform the function at all. Responses are summarised and an index score

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generated. The range of scores is 0% (no disability) to 100% (severe disability).

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Compensation definition

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Compensation was defined as the participant known to have made a compulsory third (CTP) claim within 12 months of injury, which was the maximum amount of time allowed to initiate

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a compensation claim in the ACT. Participants known to have lodged a public liability claim or a workers compensation claim which then converted to a CTP claim were also included in the compensation group. Claimants were identified through a review of the CTP insurance database and personal interview. Also determined, using similar methods were the number of participants who engaged a lawyer.27 When assessing the effect of compensation on health for the entire cohort, while controlling for study group allocation, compensation was categorised into three independent groups: those not eligible to claim compensation (notcompensable); those who were eligible to claim compensation and lodged a claim (compensation-claim); and those who were eligible to claim compensation, but did not lodge a claim (compensable but no claim).

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Intervention study The control group of patients were enrolled from September 2006 to July 2007, followed by

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an intervention group that were recruited from August 2007 to May 2008. Participants in the control group received the standard of care usually provided to residents of the ACT

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following a road traffic crash. Participants in the intervention group were evaluated by a

musculoskeletal physician who provided the patient with a detailed explanation of the nature

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and likely natural progression of their injuries. In most cases this involved an explanation of

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pain management and pain physiology, promotion of self-management, and encouragement of early activity using the aid of a presentation. A treatment plan was discussed and written

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treatment advice was provided. Where appropriate, a simple, written home-exercise programme was prescribed. The intervention was supported by an education program. The

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objective of the education programme was to disseminate information on evidence based

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guidelines related to the assessment and management of musculoskeletal injury sustained in road traffic crashes. Patient educational materials included brochures and booklets which

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provided information on healing, pain, types of musculoskeletal injury and area-specific exercises for soft tissue injury following a crash.

Statistical methods

Data were analysed using SPSS version 21.0. Shapiro–Wilk tests were used to determine if the data were normally distributed. Baseline characteristics of two groups, those in the control group and those in the intervention group were compared. For continuous data where normality could be assumed, independent t tests were performed. The Mann–Whitney U-test was used to compare skewed continuous data. Chi-squared tests were used for categorical data.

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Explanatory variables and each health measure were assessed in univariate analysis using the generalised linear model. Variables that had a significance of 0.1 were considered for inclusion in the final regression model. Based on univariate analysis (data not shown) and

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clinical relevance the final multiple regression model used fixed effects of age, sex, selfreported prior general health, ISS group and study group (allocation) as well as values of the

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corresponding outcome variable at baseline. Relationships between compensation status at baseline and various study outcomes at 12 months were assessed using linear or logistic

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regression. Similar approaches were used to determine whether the effects of the intervention

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were statistically significant among participants who claimed compensation. Two-tailed tests

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were used for all analyses.

Results

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As reported in our previous paper13, the final study sample was comprised of 193 people, of

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whom 95 and 98 were enrolled in the control and intervention groups respectively. They were 16% (193/1222) of people presenting to the Emergency Departments over the study

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period from September 2006 to May 2008. The reasons for attrition are provided in the other paper13. Recruitment of participants occurred at a mean of 9.3 (range 1 to 25) days following the road traffic crash. At final follow-up 82 (86%) of control group participants and 75 (76%) intervention group participants completed the 12-month questionnaire.

Compensation status and baseline characteristics of study sample Of the 193 participants at baseline, there were 2 participants for whom the claim status was unknown, and hence, were excluded from analyses i.e. leaving 191 participants. Table 1 shows that there were 69, 67 and 55 participants who claimed compensation, eligible to claim but did not claim and ineligible to claim, respectively. Those who claimed compensation

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were more likely to be female, speak a language other than English at home, and have a higher number of injured body sites.

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Prospective analyses assessing health-related quality of life The entire cohort was classified according to compensation status. Health outcome measures

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for the three compensation groups at baseline and 12 months are shown in Table 2. The

unadjusted means of all study outcomes were lowest in the compensation group at baseline,

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with the magnitude of the difference continuing at 12 months.

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After adjustment for baseline injury and other factors over the duration of the study, participants who were in the compensable and claimed versus the compensable and not

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claimed group had significantly lower scores in six out of the eight SF-36 domains as well as a lower MCS and PCS at the 12-month follow-up (Table 3). For these domains, differences in

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the adjusted means between compensable participants who did versus those who did not

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claim ranged from 3.0 (‘general health perception’) to 7.4 ('role limitation due to emotional problems’). Compensable participants who claimed compared to the non-compensable group

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had adjusted mean scores 6.7-, 8.0-, 5.7-, 7.5-, 7.6- and 6.3-units lower in the ‘physical functioning’, 'role limitation due to physical problems', 'bodily pain', ‘social functioning’, 'role limitation due to emotional problems’ and the PCS, 12 months later, respectively. The interaction of compensation eligibility status and study group status was not

statistically significant for any measure, indicating that the effect of the intervention did not differ between compensation eligibility statuses. Of the 69 participants who claimed compensation and were re-surveyed 12 months later, only 57 (29 control and 28 intervention subjects) had complete health status data at follow-up. There were no significant differences in mean scores in either of the SF-36 domains and/or the MCS and PCS, between the intervention and control groups (Online Supplementary Table 1).

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Prospective analyses assessing anxiety, depression and disability After multivariable adjustment, claim status at baseline was not significantly associated with

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anxiety 12 months later (Table 4). However, compensable participants who claimed versus those who were compensable but did not claim or were non-compensable had 1.8 (p=0.01)

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and 1.7 (p=0.04) lower mean HADS-depression subscale scores, respectively (Table 3).

Further, compensable and not claimed participants versus claimants were 70% less likely to

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report mild, moderate or severe depression (HADS depression subscale score ≥8),

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multivariable adjusted OR 0.30 (95% CI 0.11-0.86). Differences in adjusted mean FRI scores between participants who claimed compensation compared to those who were compensable

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but did not claim and those not compensable were 8.9% and 10.0% (both p=0.01), after 12 months, respectively (Table 4). Anxiety, depression and disability scores were not

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significantly different between those receiving the intervention versus the usual care at the

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Discussion

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12-month follow-up (Online Supplementary Table 2).

This prospective study demonstrated that people with mild to moderate musculoskeletal injuries who claimed compensation compared to those who were ineligible for compensation, or those who were compensable but did not claim compensation had poorer quality of life and mental health, and greater disability, 12 months later. These associations persisted after adjusting for potential confounders such as age, sex, and injury severity scores. The early intervention program did not appreciably influence health status 12 months after injury. The finding of worse health at 12 months in people claiming compensation is consistent with other studies 9, 12, 28 and confirms our earlier published results.13 Claiming compensation had a significant impact on a number of SF-36 indices 12 months later, including the PCS,

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social function and role limitation due to physical and emotional problems domains. The observed magnitude of difference in SF-36 scores between claimants and non-claimants was ~3-8 units over one year. This is within the range of 3-10 points which was previously

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defined as a meaningful difference in quality of life scores in a clinical setting.29 Specifically, the differences between claimants and non-claimants were more marked in relation to the SF-

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36 physical and functional indices. It is unlikely that baseline physical injury severity was responsible for these observed differences 12 months after injury, as we had adjusted for

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baseline ISS in all multivariate analyses. However, higher baseline pain, disability, and

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anxiety, and a worse perceived injury state could have provided the impetus for claiming compensation and contributed to poorer long-term outcomes in those who claimed

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compensation. A Danish study of people with mild to moderate injuries after a road traffic crash demonstrated that health utilisation in the 12 months prior was higher in people who

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claimed compensation compared with a control group.30 Moreover, people who chose to

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claim in the future had a higher proportion of health disorders and a much higher use of prescription drugs.30 This suggests that people who claim compensation are more vulnerable

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because they have a different pre-crash health profile, and consequently, they may benefit from a different type of management that is more structured and supportive. There are a number of studies that report claiming compensation as being prognostic

for poor recovery from whiplash injuries,16, 28, 31-33 however, to our knowledge this is the first study to evaluate the effect of an early intervention program on health outcomes of people with mild to moderate musculoskeletal injuries depending on compensation claim status. The intervention encouraged people to self-manage; it provided reassurance of the benign nature of the injury and promoted a return to normal activities. Though, the early intervention did not lead to any statistically significant improvements in health outcomes over the 12 months. Nevertheless, some of the observed differences in health outcomes between the intervention

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and control group could be considered as clinically relevant. For instance, a clinically meaningful difference of 5.0- and 5.2-units 29 in the SF-36 physical functioning and vitality domain scores was observed between the intervention and control groups, respectively, 12

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months later. Also at follow-up, control participants reported mild anxiety (score of 9.8) compared to a score of 7.5 (no anxiety) reported by participants in the intervention arm.

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Hence, while statistically non-significant differences were observed (most likely due to the

small sample size and inadequate statistical power); it is possible that the intervention could

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have resulted in clinically meaningful improvements in certain health measures. In future, an

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adequately powered study with a longer follow-up period could better determine the impacts of this early intervention on recovery after injury.

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Alternatively, contact with the compensation system could have negated the effect of the positive messages affirming a good prognosis. The compensation process focuses the

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injured person on the potential for long-term disability and a negative outcome. It encourages

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the use of medical resources, not for the purpose of recovery, but to assess the extent of disability and predict its future course and thus focuses on the potential for harm, rather than

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on the likelihood of a fast recovery. Patients are generally pessimistic about their recovery,34 and it is conceivable that exposure to a system which focuses on symptom severity and raises the possibility of a poor and prolonged recovery, further reduces expectation of recovery. Poor expectation of outcome has been shown to influence disability at six months following whiplash injury;35-37 however, whilst it is feasible that poor expectation of outcome may result from exposure to the compensation system, it is equally feasible that poor expectation provides the initial incentive to claim compensation. If this is so, the intervention program failed to boost the participants’ expectations of a good recovery. This study has strengths in the early collection of baseline data, the use of well validated health outcome measures and careful determination of compensation status.

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Nevertheless, there are some weaknesses which may have contributed to the intervention failing to demonstrate a greater effect in participants who claimed compensation. When evaluating the effect of the intervention on outcome for all patients in the intervention group

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compared with the control group regardless of compensation status (unpublished data), it was found that a lack of compliance and frequent use of co-interventions diluted the effect of the

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treatment. In addition, the segmental cohort design may have resulted in some selection bias. A cluster randomised controlled trial (RCT) in which the two arms of the study would have

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been conducted in different cities was considered as an alternative, however, a cluster RCT

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may not have captured the consistent influence of the ACT health and CTP scheme, thus introducing additional variables such as differences in compensation schemes and healthcare

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systems. Furthermore, in a compensation environment, it is conceivable that financial incentives may lead some people to over-state symptoms. This may be reflected in worse

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self-reported health measures. However the extent to which measurement error exists is

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difficult to determine. Finally, we cannot discount the possibility of reverse causality, particularly as Spearing et al. 38 recently showed that when reverse causality bias is

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addressed, claiming compensation appears to have a beneficial effect on recovery. Having said that we would expect persons who were not eligible to claim compensation to have worse health outcomes 12 months later, as there is likely to be a subgroup of people in this group who had worse health prior to the crash that were in need of greater support post-crash (support that the compensation system provides) but did not have access to it. Therefore, in the presence of reverse causality these persons would be expected to have poorer health at 12 months; this is contrary to what we observed. Nevertheless, future research clearly needs to address reverse causality bias when examining compensation-related factors and health status.38

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There are a number of considerations this research has raised for the compensation system. First, removing barriers to early medical treatment such as those that prevent commencement of treatment if insurance cover is unclear or the claim is disputed, are more

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likely to result in a favourable health outcome. In fault-based schemes this may include early claim notification incentives and allowing payments for medical treatments without the need

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to prove fault. Secondly, simplifying the compensation process to make it less intimidating for injured people to navigate may make it more accessible and may reduce the need for

Finally, limiting access to compensation for ‘pain and suffering’ and other non-

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14, 15, 32, 39, 40

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lawyer representation which is known to be a strong negative prognostic factor for recovery.

economic loss for minor injury claims should be encouraged. The flow-on benefit of improving health outcome and reducing the number of small claims has been demonstrated in

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previous studies. 9, 41

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In summary, people who claim compensation had poorer quality of life, depression and

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greater disability at 12 months than both people who are ineligible to claim compensation and those who are eligible but choose not to claim compensation. Access to an early intervention

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program failed to result in an appreciable improvement in health status for people who claimed compensation.

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compensation on health care utilisation in a trauma cohort. Medical Journal of Australia 2009; 190 619-22.

33.Joslin CC, Khan SN and Bannister GC. Long-term disability after neck injury. a comparative study. Journal of Bone & Joint Surgery - British Volume 2004; 86 1032-4. 34.Bostick GP, Ferrari R, Carroll LJ, Russell AS, Buchbinder R, Krawciw D, et al. A population-based survey of beliefs about neck pain from whiplash injury, work-related neck pain, and work-related upper extremity pain. European Journal of Pain: Ejp 2009; 13 300-4. 35.Hill JC, Lewis M, Sim J, Hay EM, Dziedzic K, Hill JC, et al. Predictors of poor outcome in patients with neck pain treated by physical therapy. Clinical Journal of Pain 2007; 23 68390.

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36.Holm LW, Carroll LJ, Cassidy JD, Skillgate E and Ahlbom A. Expectations for recovery important in the prognosis of whiplash injuries. PLoS Medicine / Public Library of Science 2008; 5 e105.

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37.Rubinstein SM, Knol DL, Leboeuf-Yde C, de Koekkoek TE, Pfeifle CE, van Tulder MW, et al. Predictors of a favorable outcome in patients treated by chiropractors for neck pain.

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Spine 2008; 33 1451-8.

38.Spearing NM, Connelly LB, Nghiem HS and Pobereskin L. Research on injury

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compensation and health outcomes: ignoring the problem of reverse causality led to a biased

an

conclusion. J Clin Epidemiol 2012; 65 1219-26.

39.Gun RT, Osti OL, O'Riordan A, Mpelasoka F, Eckerwall CG, Smyth JF, et al. Risk factors

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for prolonged disability after whiplash injury: a prospective study. Spine 2005; 30 386-91. 40.Osti OL, Gun RT, Abraham G, Pratt NL, Eckerwall G, Nakamura H, et al. Potential risk

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90-4.

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factors for prolonged recovery following whiplash injury. European Spine Journal 2005; 14

41.Cameron ID, Rebbeck T, Sindhusake D, Rubin G, Feyer AM, Walsh J, et al. Legislative

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change is associated with improved health status in people with whiplash. Spine 2008; 33 250-4.

20 Page 20 of 28

Acknowledgements This study was funded by the ACT Road Safety Trust and Insurance Australia Group. Neither funder had a role in data collection, analysis or report writing. We thank Alexandra Pearce

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for assistance with manuscript preparation and Janine Lourensz for her assistance with data

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collection.

21 Page 21 of 28

Conflict of Interest Statement

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The authors declare that this study was funded by the ACT Road Safety Trust and Insurance Australia Group. Neither funder had a role in data collection, analysis or report writing. No other conflicts of interest exist that may inappropriately influence the findings of this study.

22 Page 22 of 28

Table 1. Baseline characteristics of study participants stratified by claim status

Female, n (%)

Compensable and

(n=55)

compensation (n=69)

not claimed (n=67)

34.7 (14.3)

39.0 (14.3)

37.9 (13.2)

0.21

44 (65.7)

45 (65.2)

0.04

14 (20.3)

10 (14.9)

0.03

25 (45.5) 2 (3.6)

M

Language other than English spoken at home, n (%)

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Age (years), mean (SD)

Claimed

an

Not compensable

Variable

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Table 1

pa

30 (54.5)

30 (43.5)

32 (47.8)

0.47

Tertiary qualified, n (%)

41 (74.5)

43 (62.3)

45 (67.2)

0.35

47 (85.5)

59 (85.5)

60 (89.6)

0.73

26 (47.3)

28 (40.6)

19 (28.4)

0.53

19 (34.5)

28 (40.6)

34 (50.7)

5 (9.1)

7 (10.1)

7 (10.4)

5 (9.1)

6 (8.7)

7 (10.4)

5 (9.1)

7 (10.1)

7 (10.4)

0.97

51 (92.7)

62 (89.9)

60 (89.6)

0.81

3.05 (1.33)

3.61 (1.74)

3.03 (1.47)

0.05

43 (78.2)

57 (82.6)

60 (89.6)

0.23

d

Married/ Defacto, n (%) b

Income group, n (%) $0-$41,599 $41,600-$103,999

Did not answer Living alone, n (%)

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≥$104,000

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Paid work status , n (%)

Self-reported general health (Good/ very good/ excellent), n (%)

Number of injured body sites (self-report), mean (SD) Injury Severity Score group (ISS 1-3), n (%)

Page 23 of 28

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Neck or back injury, n (%)

27 (49.1)

44 (63.8)

Thoracic or lumbar spine

7 (12.7)

Upper/lower limb

9 (16.4)

Shoulder

7 (12.7)

Other

1 (1.8)

36 (53.7)

12 (17.4)

8 (11.9)

13 (18.8)

9 (16.4)

10 (14.5)

7 (10.4)

3 (4.3)

4 (6.0)

0 (0)

3 (4.5)

d

For comparison between three groups. Full or part-time

31 (44.9)

an

11 (20.0)

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Chest

0.35

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b

20 (36.4)

0.10

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Neck

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Primary site of injury, n (%)

45 (67.2)

Page 24 of 28

Table 2

Table 2. Unadjusted means and standard deviation of study outcomes of interest at baseline and at 12-month follow-up Compensable

Claimed

problems

Bodily pain

General health perception

Mean (SD)

0

29.3 (11.8)

36.7 (11.7)

34.4 (11.7)

12

42.7 (14.0)

49.3 (9.0)

51.1 (8.6))

0

24.8 (8.5)

30.6 (12.1)

28.8 (11.1)

12

43.1 (12.3)

49.4 (8.5)

52.2 (8.5)

0

28.9 (6.7)

33.4 (9.0)

32.6 (8.7)

12

43.7 (12.2)

47.1 (11.0)

50.6 (9.2)

0

47.8 (8.1)

50.5 (7.6)

47.5 (7.9)

45.6 (10.9)

48.6 (9.3)

48.7 (9.5)

33.3 (9.9)

36.7 (10.1)

38.0 (10.5)

12

44.3 (12.2)

47.5 (10.2)

49.8 (9.7)

0

23.9 (9.7)

31.5 (11.3)

30.5 (11.1)

12

40.3 (14.1)

47.4 (10.2)

49.3 (9.2)

0

20.2 (17.6)

28.7 (18.3)

34.6 (19.0)

12

38.3 (18.0)

45.9 (12.4)

47.8 (11.3)

0

31.9 (12.0)

35.3 (12.1)

38.2 (12.4)

12

41.4 (12.0)

45.7 (9.9)

46.1 (11.5)

0

33.7 (7.8)

38.8 (9.7)

34.8 (8.9)

12

45.2 (11.4)

49.7 (8.5)

52.6 (7.6)

0

28.2 (12.4)

33.3 (13.5)

38.1 (14.2)

12

40.3 (14.5)

45.6 (10.6)

47.0 (11.5)

0

10.2 (4.82)

8.67 (4.28)

8.25 (4.39)

12

8.23 (5.30)

6.60 (4.08)

5.95 (4.31)

0

7.23 (4.13)

5.91 (4.39)

5.64 (3.64)

12

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Social functioning

0

d

Vitality

Role limitation due to emotional problems

Mental health

Physical component score

Mental component score

Anxiety

Depression

cr

Mean (SD)

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Role limitation due to physical

Mean (SD)

an

Physical functioning

compensable

Time

M

Outcome variable

claimed

Not

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compensation

and not

Page 25 of 28

5.91 (4.86)

3.93 (3.27)

3.55 (3.38)

0

62.9 (19.1)

50.4 (22.3)

52.6 (19.8)

12

30.5 (26.9)

21.2 (17.9)

16.3 (15.4)

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Disability

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Page 26 of 28

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Table 3

Table 3. Association between compensation status at baseline and SF-36 scores at 12 month follow-up, stratified by compensation status

Physical functioning

41.3 (37.2, 45.5)

Role limitation due to physical

M

39.0 (35.5, 42.6)

Compensable and not claimed

problems

p

Not compensable

p

47.2 (43.1, 51.3)

0.005

48.0 (43.2, 52.7)

0.004

45.8 (42.3, 49.3)