Cost-effectiveness of vocational rehabilitation for chronic pain

Background: Although vocational rehabilitation is a widely advocated intervention for workers on sick leave due to subacute or chronic non-specific musculoskeletal pain, the optimal dosage of effective and cost-effective vocational rehabilitation remains unknown. The objective of this paper is to describe the design of a non-inferiority trial evaluating the effectiveness and cost-effectiveness of a 100-hour multidisciplinary vocational rehabilitation programme compared with a 40-hour multidisciplinary vocational rehabilitation programme on work participation for workers on sick leave due to subacute or chronic musculoskeletal pain.
Methods: A non-inferiority study design will be applied. The study population consists of workers who are on part-time or full-time sick leave because of subacute or chronic non-specific musculoskeletal pain. Two multidisciplinary interventions following the bio-psychosocial approach will be evaluated in this study: a reference intervention of ~100 treatment hours and an experimental intervention of ~40 treatment hours, both delivered over a maximum of 15 weeks. The content of the reference intervention comprises five modules: work participation coordination, graded activity, cognitive behavioural therapy, group education, and relaxation. The content of the experimental intervention comprises work participation coordination and a well-reasoned choice from the other four modules. Four rehabilitation centres participate in this study, with each delivering both interventions. Patients will be randomized into one of the interventions, stratified for the duration of sick leave (<6 weeks or ¡Ý6 weeks) and type of sick leave (part-time or full-time). The primary outcome is work participation, measured by self-reported sick leave days, and will be assessed at baseline, mid-term, discharge, and at 2, 4, 6, 8, 10, and 12 months follow-up. Secondary outcomes are work ability, disability, quality of life, and physical functioning, and will be assessed at baseline, discharge, and at 6 and 12 months follow-up. Cost-effectiveness outcomes are absenteeism, presenteeism, and health care usage. Cost-effectiveness will be evaluated from the societal and employer perspective.
Discussion: The results obtained from this study will be useful for vocational rehabilitation practice, and will provide stakeholders relevant insights into two versions of vocational rehabilitation.

The study will be performed in four vocational rehabilitation centres in the Netherlands.

There is non-inferiority on return to work between moderate (40-hour) and extensive (100-hour) vocational rehabilitation, and there will be differences in cost-effectiveness in favour of the moderate program.

Self-reported data will be collected using web-based questionnaires at baseline (T0), mid-term (T1), at discharge (T2), and at 2, 4, 6, 8, 10 and 12 months follow-up after discharge (T3-T8). At each data point, participants will receive an email with login data and the request to complete questionnaires on a website. If participants do not complete the questionnaire within a week, they will be reminded by email. If the questionnaires are not completed after this reminder, patients will be telephoned by a researcher (TB).

Primary outcome T0-T8
Secundaire outcomes:
- WAI: T0, T2, T5, T8
- RAND-36: T0, T2, T5, T8
- PDI: T0, T2, T5, T8
- EQ-5D: T0, T2, T5, T8
- TiC-P: T0, T2, T4, T6, T8
- iPCQ (presenteeism): T0-T8

Experimental 40-hour intervention
The experimental intervention is a multidisciplinary bio-psychosocial group-based vocational rehabilitation programme, and consists of work participation coordination (10 hours), and a choice of 30 hours of a set of modules offered in the reference intervention, such as graded activity, cognitive behavioural therapy, group education, and relaxation. These modules are described in detail in additional file 1. Since the choice of 30 hours of modules will be prioritized by the professionals after the multidisciplinary screening at baseline, the content may differ per patient. The experimental programme lasts a maxim of 40 hours in 15 weeks. The programme will be extended if: a patient has achieved 25-50% return to work (RTW) improvement (RTW improvement: the percentage of hours at work per week pertaining to contract hours at the end of the experimental programme, compared with hours at work per week pertaining to contract hours at baseline), and the team expresses strong arguments that the patient will likely benefit from the extension. However, this should occur in no more than 5% of the cases.

Reference 100-hour intervention
The reference intervention is a multidisciplinary bio-psychosocial group-based vocational rehabilitation programme, and encompasses a set of modules: work participation coordination, graded activity, cognitive behavioural therapy, group education, and relaxation. The reference intervention consists of approximately 100 hours, and is an existing vocational rehabilitation intervention programme in the Netherlands conducted by fourteen rehabilitation centres, four of which will participate in this study. The reference intervention is delivered over a period of 15 weeks with two sessions (~3,5 h / session) per week. The reference intervention in this trial appears similar to other trials in the vocational rehabilitation field, but the reference programme has a longer duration (in weeks) and there are more graded activity hours as compared with similar studies.