Background
In Norway, musculoskeletal (MSK) disorders present the greatest burden to future health and welfare services [
1,
2]. The high economic costs related to sick leave include productivity loss and use of health care services. Importantly, through the Norwegian Labour and Welfare Administration (NAV), the welfare system in Norway covers 100% of the worker’s salary up to 52 weeks of sick leave after the first 16 days, which are paid by the employer.
To address the substantial costs related to sick leave, effective interventions targeting obstacles to return to work (RTW) are needed. In a best evidence synthesis of 94 systematic reviews with half of the studies exploring MSK disorders [
3], risk factors associated with poorer RTW outcomes were older age, being female, higher pain or disability, depression, higher physical work demands, previous sick leave, unemployment, and activity limitations. Better RTW outcomes were found in people with higher education and socioeconomic status, higher self-efficacy beliefs, optimistic expectations for recovery, lower severity of the injury/illness, better RTW coordination and in those receiving multidisciplinary interventions involving the workplace and key stakeholders.
There is strong evidence that interventions with a health focus, service coordination involving the workplace, and work modifications reduce the proportion of people on sick leave [
4]. Motivational interviewing (MI) [
5] is an intervention that targets behavior change that has been suggested to be useful in an RTW context [
6]. A systematic review including five randomized controlled trials (RCTs) reported weak evidence for the effectiveness of MI to facilitate RTW, particularly for people with less serious conditions and short work absences [
7]. A recent systematic mapping review by our research group [
8] with the objective of mapping all types of empirical research on MI as a method to help people with MSK disorders return to work revealed only three papers from two RCTs: A Norwegian RCT with high risk of bias showed now effect of a brief intervention including MI on RTW for 89 disability pensioners with back pain [
9], and a Canadian cluster RCT with low risk of bias including 728 claimants with chronic musculoskeletal disorders, showed that providing MI in addition to usual rehabilitation increased RTW both at discharge and at 1-year follow-up [
10,
11].
Providing vocational interventions to all people having any period of sick leave, that comprises individualized cognitive, affective and behavioral approaches, would require enormous resources. Using a stratified approach in which only individuals at high risk for long-term sick leave are targeted with the intervention, could be more efficient.
Stratified care is one approach with which to improve outcomes among people with MSK disorders. By way of example, the STarT Back trial was the first RCT to show that stratified care based on matching treatment to low back pain patients’ risk of persistent disabling pain (low, medium or high risk) resulted in better patient outcomes including fewer days lost from work, at less cost for the UK healthcare system and UK society [
12,
13]. Furthermore, a recent RCT [
14] compared the difference in the number of sickness absence days between a targeted intervention that emphasized communication (MI and problem-solving skills for the patient and their work supervisor) versus treatment as usual in people with back pain at high risk of persistent pain. The targeted intervention resulted in fewer days off work, fewer health care visits and better perceived health. Despite promising results for low back pain, to date there are few studies on stratified care for the broader group of people with MSK disorders. Several tools have been developed with which to assess MSK pain patients’ risk of persistent disabling pain, for instance the Keele STarT MSK tool [
15], and long-term work loss [
16]. A
stepped care approach to facilitate RTW was investigated in the Study of Work and Pain (SWAP) cluster RCT in the UK [
17]. General practices were randomized to either offer usual care or the SWAP intervention in addition to usual care. Patients consulting general practices in the intervention arm with MSK pain who were absent from work or struggling at work were offered access to a vocational advice service, whereby vocational advisors provided a case-managed stepwise intervention, starting with brief telephone assessment and advice, addressing obstacles to RTW [
18]. The SWAP trial showed that participants in the vocational advice arm had fewer days off work compared with those having usual care alone.
There is lack of research of the effectiveness of MI and vocational advice interventions in people on long term sick leave due to MSK disorders. The objectives of this RCT are thus to compare the effectiveness and cost-effectiveness of usual case management by NAV alone with usual case management by NAV plus MI or usual case management by NAAV plus stratified vocational advice intervention (SVAI), on RTW among people on sick leave due to MSK disorders. The objectives and hypotheses are presented in detail the statistical analysis plan in Appendix 1. This multi-arm RCT is not designed to compare the two interventions head-to-head, as this would have required an unrealistically large sample size. In addition to analyses of effectiveness of the two interventions, we will conduct health economic analyses, mediation analyses, process evaluation, and exploratory analyses of potential predictors for sick leave due to MSK disorders.
Discussion
The Norwegian Directorate of Health encourages health care providers to use MI to support health behavior change, and MI is used in NAV to facilitate RTW despite little research supporting the use of MI in people with MSK disorders [
8]. To be able to give evidence-based recommendations on the effectiveness and cost-effectiveness of MI on RTW, there is a need for large RCTs. Whilst other vocational advice interventions have shown promising results in improving RTW outcomes in individuals with MSK disorders [
17,
31], a stratified vocational advice intervention provided by physiotherapists, as included in this RCT, has not been studied previously. In this multi-arm RCT all participants receive usual case management by NAV and the two intervention groups receive additionally either MI or SVAI. This design enables us to examine the additional effect of the vocational interventions to the usual case management, however, we have not designed the study to compare the two interventions head-to-head, as this would have required an unrealistically large sample size. The primary outcome is the number of sick leave days from inclusion to the 6-month follow-up, and the sample size calculation is based on this follow-up time-point with an expected difference between the intervention groups and the usual case management group of 10 days.
Experienced professionals will educate both the NAV caseworkers and the SVAI physiotherapists to provide the interventions. However, it is difficult to conduct MI correctly with little experience [
6]. Therefore, we will pay close attention to how the NAV caseworkers and the SVAI physiotherapists will use and develop their skills in the interventions through audiotaping the sessions, score the MI interventions, and conduct monthly mentoring and supervision sessions.
Conducting RCTs with people on sick leave is dependent upon the willingness of these people to participate in research. A previous RCT on the effectiveness of inpatient multicomponent occupational rehabilitation found that less than 10% of eligible participants accepted the trial invitation [
32]. Thus, we have tried to keep the questionnaires as short as possible to prevent missing data. We will have data from all the participants on the main outcome from NAV registries and we will perform the analyses according to the intention-to-treat principle to reduce the impact of attrition bias. Nevertheless, we need more knowledge of the group that is willing to participate in research as compared to those who do not participate. This will be addressed by comparing registry data of those who are willing and those who do not participate in this RCT and the other similar ongoing RCT in Norway [
28]. The results of the RCT will provide evidence of the clinical and cost-effectiveness of MI and SVAI in addition to usual NAV case management in Norway.
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