Occupational rehabilitation and readiness for return to work in individuals with musculoskeletal complaints and mental health disorders: A randomized clinical trial

Background Musculoskeletal complaints and mental health disorders are the two leading causes of sickness absence in Norway. Despite increasing documentation of overlap in symptoms between these diagnoses groups, most occupational rehabilitation programs described in the scientific literature are diagnosis-specific. In Norway, inpatient occupational rehabilitation programs including different diagnostic groups in the same groups has been done for decades, but such programs have never been evaluated with a rigorous study design. Aims The main aim of this thesis was to assess the effects of a 4+4 days multicomponent inpatient occupational rehabilitation program compared to a less comprehensive outpatient program on sickness absence and somatic and mental health in persons with musculoskeletal- or mental health disorders. A secondary aim was to explore the usefulness of the Readiness for Return to work scale, a questionnaire developed to evaluate where sick listed individuals are in their return to work (RTW) process, by assessing the association between the scale and RTW, and comparing the scale to a single question assessing participants` expectations about length of sick leave. Methods In a randomized trial with parallel groups, individuals on sick leave with musculoskeletal complaints or common mental health disorders were randomized to the inpatient program or the outpatient program. The inpatient program consisted of Acceptance and Commitment Therapy (ACT), physical training and work-related problem-solving including creating a RTW plan and a workplace visit if considered relevant. The outpatient program consisted primarily of ACT (6 sessions during 6 weeks). The primary outcome was cumulated number of sickness absence days at 6 and 12 months follow-up based on registry data. Secondary outcomes were time until sustainable RTW and different somatic and mental health outcomes measured by questionnaires up to 12 months follow-up (paper 1 and 2). In a prospective cohort study with 9 months follow-up participants on sick leave with musculoskeletal complaints or common mental health disorders who took part in two randomized clinical trials were included. Associations between the Readiness for RTW scale and RTW was analysed using linear and logistic regression. The Readiness for RTW scale was compared to a self-reported question assessing participants` expectations about length of sick leave using adjusted/pseudo R2. Questionnaires were answered at the start and the end of rehabilitation programs and sick leave was measured using registry data (paper 3). Results 168 individuals were randomized to the 4+4 days multicomponent inpatient program (n=92) or the outpatient program (n=76) (paper 1 and 2). There was no statistical difference between the programs in median number of sickness absence days at 6 and 12 months follow-up. The hazard ratio for sustainable RTW was 0.74 (95% CI 0.48-1.32, p=0.165), in favor of the outpatient program. There were no statistically significant differences between the programs in health outcomes, except for slightly more reduced pain after the outpatient program. For participants not working at the end of rehabilitation (n=96), high scores on two dimensions (Prepared for action-self-evaluative and Prepared for action-behavioral) were associated with a higher probability of RTW and more working days (paper 3). For those working (n=121), high scores on the Uncertain maintenance dimension was associated with a lower probability of RTW and less working days. Stage allocation, allocating participants to the dimension with the highest score, was problematic due to several tied scores between (not necessarily adjacent) dimensions. Generally, models including the Readiness for RTW dimensions were not as good at explaining work outcomes as models including a single expectation question. Conclusions There was no difference between the inpatient program and the outpatient program on sick leave or sustainable RTW. There was no difference in self-reported health measures between the programs, except for slightly more reduced pain after the outpatient program. Therefore, this study presents no support that a 4+4 days inpatient multicomponent occupational rehabilitation program is superior to a less comprehensive outpatient program. Three of the Readiness for RTW dimensions were associated with RTW, but only to a lesser or similar extent than a single expectation question. Furthermore, several weaknesses with the Readiness for RTW scale were established and particularly the stage allocation approach cannot be recommended for clinical use in its current form