Musculoskeletal disorders are the main causes for sickness absence and disability benefits in Norway and the leading causes of disability worldwide. There is strong evidence that long-term sickness absence due to musculoskeletal disorders provides a poor prognosis, both in terms of work-related disability, physical and mental health, and health related quality-of-life. To assist people return to work a range of vocational rehabilitation programs exist, but the initiatives have not been able to reduce the number of people who are on sick leave due to musculoskeletal disorders. In Norway, The Norwegian Labour and Welfare Administration (NAV) case-workers have taken such approaches in use, primarily by teaching their employees with user contact in how to use Motivational Interviewing (MI). However, the evidence on the effectiveness of MI on return to work is highly uncertain. The objectives of this project are to compare the effectiveness and cost-effectiveness of usual case management alone with usual case management plus MI or usual case management plus stratified vocational advice intervention (SVAI), on RTW among people on sick leave due to musculoskeletal (MSK) disorders. All musculoskeletal diagnoses will be included. A multi-arm randomised controlled trial with 150 participants in each group will be conducted within the NAV system in Norway to evaluate these research questions.

The main objective of this project is to evaluate the effectiveness of usual case management plus motivational interviewing (MI), provided by trained Norwegian Labour and Welfare Administration (NAV) case-workers, and usual case management plus a Stratified Vocational Advice Intervention (SVAI), including principles of MI and vocational advice provided by trained physiotherapists, compared to usual case management alone on return to work among people on sick leave due to a musculoskeletal disorder. A multi-arm randomised controlled trial (RCT) will be conducted in order to respond to the following specific research questions:

RQ 1a Is there a difference between usual case management plus MI and usual case management alone in reducing sickness absence days at 6 months follow-up among individuals who have been on sick leave for >7 weeks due to a musculoskeletal disorder?

RQ 1b Is there a difference between usual case management plus SVAI and usual case management alone in reducing sickness absence days at 6 months follow-up among individuals who have been on sick leave for >7 weeks due to a musculoskeletal disorder?

RQ 2a Is there a difference between usual case management plus MI and usual case management alone in reducing sickness absence days at 12 months follow-up among individuals who have been on sick leave for >7 weeks due to a musculoskeletal disorder?

RQ 2b Is there a difference between usual case management plus SVAI and usual case management alone in reducing sickness absence days at 12 months follow-up among individuals who have been on sick leave for >7 weeks due to a musculoskeletal disorder?

RQ 3a Is there a difference between usual case management plus MI and usual case management alone in time until sustained RTW during 12 months follow-up among individuals who have been on sick leave for >7 weeks due to a musculoskeletal disorder?

RQ 3b Is there a difference between usual case management plus SVAI and usual case management alone in time until sustained RTW during 12 months of follow-up among individuals who have been on sick leave for >7 weeks due to a musculoskeletal disorder?

RQ 4a Is there a difference in the proportions of participants who receive sick leave benefits each month during 12 months of follow-up between usual case management plus MI compared to usual case management alone?

RQ 4b Is there a difference in the proportion of individuals who receive sick leave benefits each month during 12 months of follow-up between usual case management plus SVAI compared to usual case management alone?

RQ 5a Is there a difference in cost-effectiveness, cost-utility and cost-benefit during 6 months of follow-up between individuals on sick leave with musculoskeletal disorders who receive usual case management plus MI compared to those who receive usual case management alone?

RQ 5b Is there a difference in cost-effectiveness, cost-utility and cost-benefit during 6 months of follow-up between individuals on sick leave with musculoskeletal disorders who receive usual case management plus SVAI compared to those who receive usual case management alone?

RQ 6a Is there a difference in cost-effectiveness, cost-utility and cost-benefit during 12 months of follow-up between individuals on sick leave with musculoskeletal disorders who receive usual case management plus MI compared to those who receive usual case management alone?

RQ 6b Is there a difference in cost-effectiveness, cost-utility and cost-benefit during 12 months of follow-up between individuals on sick leave with musculoskeletal disorders who receive usual case management plus SVAI compared to those who receive usual case management alone?

RQ 7a Is there a difference in musculoskeletal health during 12 months of follow up between individuals on sick leave with musculoskeletal disorders who receive usual case management plus MI compared to those who receive usual case management alone?

RQ 7b Is there a difference in musculoskeletal health during 12 months of follow up between individuals on sick leave with musculoskeletal disorders who receive usual case management plus SVAI compared to those who receive usual case management alone?

The following hypotheses will be tested:

H 1a There is no difference in number of sickness absence days between participants who receive usual case management plus MI compared to those who receive usual case management alone at 6 months follow-up.

H 1b There is no difference in number of sickness absence days between participants who receive usual case management plus SVAI compared to those who receive usual case management alone at 6 months follow-up.

H 2a There is no difference in number of sickness absence days between participants who receive usual case management plus MI compared to those who receive usual case management alone at 12 months follow-up.

H 2b There is no difference in number of sickness absence days between participants who receive usual case management plus SVAI compared to those who receive usual case management alone at 12 months follow-up.

H 3a There is no difference in time until first sustained RTW between participants who receive usual case management plus MI compared to those who receive usual case management alone during 12 months follow-up.

H 3b There is no difference in time until first sustained RTW between participants who receive usual case management plus SVAI compared to those who receive usual case management alone during 12 months of follow-up.

H 4a There is no difference in the proportions of participants who receive sick leave benefits each month between usual case management plus MI compared to usual case management alone during 12 months of follow-up.

H 4b There is no difference in the proportions of individuals receiving sick leave benefits each month between usual case management plus SVAI compared to usual case management alone during 12 months of follow-up.

H 5a There is no difference in cost-effectiveness, cost-utility and cost-benefit between usual case management plus MI compared to usual case management alone during 6 months of follow up.

H 5b There is no difference in cost-effectiveness, cost-utility and cost-benefit between usual case management plus SVAI compared to usual case management alone during 6 months of follow up.

H 6a There is no difference in cost-effectiveness, cost-utility and cost-benefit between usual case management plus MI compared to usual case management alone during 12 months of follow up.

H 6b There is no difference in cost-effectiveness, cost-utility and cost-benefit between usual case management plus SVAI compared to usual case management alone during 12 months of follow up.

H 7a There is no difference in musculoskeletal health between participants who receive usual case management plus MI compared to those who receive usual case management alone during 12 months of follow-up.

H 7b There is no difference in musculoskeletal health between participants who receive usual case management plus SVAI compared to those who receive usual case management alone during 12 months of follow-up.

A multi-arm RCT with a full-scale health economic evaluation and mediator analysis will be conducted. In order to avoid contextual contamination effect only NAV offices in which the employees have not received any previous MI training will be included. All eligible participants will be asked to participate.

The head NAV office in Oslo will provide weely lists of persons meeting the eligibility criteria. We will contact eligible people by phone and give information about the study. Elibible persons who are interested will then receive a link to the informed consent and the baseline questionnaire.

MI intervention: In addition to usual case management, the MI group will receive 2 motivational interviews provided by a NAV case-worker. The case-workers will be educated and mentored throughout the study period. The first MI will be face-to-face, while the second may by phone, but preferable face-to-face.The interviews will be given in week 8/9 of the sick leave period, and then again after approximately 2 weeks.

SVAI intervention: In addition to usual case management, the SVAI group will be followed up by trained physical therapists. This group will be stratified into risk groups for long term sick leave; an "at risk group" and a "high risk group". The at risk group will receive 1-2 phone calls with emphasis on identifying obstacles for return to work, and solutions for resolving these obstacles. The high risk group will be followed up 3-4 times. The first follow-up is by phone, the remaining follow-ups can be either by phone or face to face meetings and can include a workplace visit. The SVAI intervention will end before week 26 of the participants' sick leave period.

Usual case management: The Norwegian welfare state has a system for following up people on sick leave, including a follow-up plan developed by the worker and the employer by week 4 of the sick leave period, a dialogue meeting between the worker and the employer by week 7, and a second dialogue Meeting including a NAV caseworker, by week 26.

The study flow:

Baseline recruitment will occur by week 8 of the sick leave period. The two interventions will start immediately after randomization and baseline assessments. The questionnaires will be sent electronic through a secure system from University of Oslo at baseline, and after 3, 6, 9, and 12 months.

A pilot study will be conducted prior to start of the RCT to test the study protocol including the recruitment procedure, the randomisation procedure, the information flow between researchers, physical therapists, NAV case workers and study participants, and the interventions (MI and SVAI). The pilot study will end by the first 100 included participants (August 31. 2019). The participants in the pilot study will be included in the RCT as long as the protocol will not be changed with respect to the scientific method and research questions (internal pilot study).

A fidelity study of the MI and SVAI interventions will be conducted to measure how well the trained personnel is using the methods and interventions as intended. For the MI arm, a developed instrument (Motivational Interviewing Treatment Integrity Coding Manual 4.2.1) will be used to score the feasibility from audio recordings of all NAV case-workers who do the MI intervention. For the SVAI intervention, feasibility will be measured by both audiotaping and from the telephone script/journal that the SVAI physiotherapists fill out during the talk with the study participant. The investigators plan to do 20-25 audiotapes of the 5 SVAI physiotherapists.

Inclusion Criteria:

• Have musculoskeletal disorders
• Live in South-East Norway
• Have been on sick leave for 8 weeks with a current sick-leave status of 50%-100%
• Have a job to return to

Exclusion Criteria:

• Have serious somatic or psychological disorders (e.g. cancer, psychotic disorders)
• Have specific disorder requiring specialized, ongoing treatment;
• Are pregnant
• Are self-employed or work free lance
• Have insufficient Norwegian or English speaking or writing skills to participate in group session and fill out questionnaire.

In the written consent, the three groups will be described. Thus the participants will understand which group they are in after the first telephone call, and consequently not be blinded. The interventions are:

1. Motivational interview by 2 meetings between participant and the NAV case-worker. Both the NAV case-workers and the participants will know that the intervention is motivational interviewing because it is only in this arm a NAV case-worker will do the intervention.
2. Stratified vocational advice intervention (SVAI): a physiotherapist will call the study participants, and both the physiotherapist and the participants will know that they are in the SVAI intervention group from the informed consent.

The researchers will be blinded to group allocation throughout the study recruitment and assessment up to the 6-month follow-up.