Cost-effectiveness of vocational rehabilitation for workers on sick leave due to subacute or chronic musculoskeletal pain

Chronic musculoskeletal pain is a major health problem associated with
decreased functioning and quality of life, sick leave, and increased direct and
indirect medical costs. The majority of the costs (77-93%) are contributed to
indirect costs due to sick leave from work or productivity loss while at work.
Chronic musculoskeletal pain arises when acute musculoskeletal pain does not
recover within six weeks, which occurs in 10-20% of the cases. Arbitrary after
six weeks duration it is considered subacute musculoskeletal pain (SMP), and if
the pain is still present after 12 weeks it is considered chronic
musculoskeletal pain (CMP). If there is no clear medical explanation, the
chronic musculoskeletal pain is called **non-specific**. Vocational
rehabilitation is a widely advocated intervention for absent workers with
subacute or chronic non-specific musculoskeletal pain. Vocational
rehabilitation is **a multi-professional evidence-based approach that is
provided in different settings, services, and activities to working age
individuals with health-related impairments, limitations, or restrictions with
work functioning, and whose primary aim is to optimize work participation**.
Research shows that vocational rehabilitation improves return to work. However,
the dose-effect relation of (cost-)effective vocational rehabilitation is
unclear. In literature and in vocational rehabilitation practice, there are two
programs presented: extensive (>100 treatment hours) and moderate (<=40
treatment hours) vocational rehabilitation. There are two assumptions for the
(cost-)effectiveness of these two programs. The first assumption is mainly
based on one randomized controlled trial in which extensive vocational
rehabilitation was compared with moderate vocational rehabilitation and usual
care for workers on sick leave due to chronic musculoskeletal pain.
Participants were classified based on prognosis for return to work, i.e. good,
medium, or poor, and randomized to one of the three groups. The study found
that patients classified with poor prognosis benefited most from the extensive
program, and patients classified with medium prognosis benefited both from the
moderate and extensive program on return to work. In addition, in a
cost-effectiveness study which included the same study population (but without
the classification), only the moderate program showed significant
cost-effectiveness , and only in men. The second assumption is that moderate
programs may be non-inferior or even superior compared with extensive programs
in facilitating return to work and cost-effectiveness in patients with subacute
or chronic musculoskeletal pain. This assumption is confirmed by a systematic
review in which it was found that vocational rehabilitation programs comprising
<32 treatment hours were more effective on return to work (RR = 1.45) in people
with sick leave from work because of subacute or chronic musculoskeletal pain
compared with more extensive vocational rehabilitation programs, comprising
33-70 treatment hours (RR = 1.09) or more than 70 treatment hours (RR = 1.00).
However, the same review stated that these findings may reflect on subacute
musculoskeletal pain, and that for the **difficult chronic cases** extensive
programs might be more (cost-)effective compared with moderate programs, as
also stated in the first assertion. In summary, the optimal dosage of
(cost-)effective vocational rehabilitation is currently unknown. Patients with
difficult chronic cases with poor prognosis for return to work may benefit most
from extensive programs, but other research suggests that moderate programs
might be non-inferior or even superior compared with extensive programs. These
findings has lead to the hypotheses that there is non-inferiority on return to
work between moderate and extensive vocational rehabilitation, and that there
will be differences in cost-effectiveness in favour of the moderate program.

1) For workers on sick leave due to subacute or chronic musculoskeletal pain,
is a 40 hours vocational rehabilitation program non-inferior on work
participation compared with a 100 hours vocational rehabilitation program?
2) For workers on sick leave due to subacute or chronic musculoskeletal pain,
is a 40 hours vocational rehabilitation program more cost-effective compared
with a 100 hours vocational rehabilitation program?

A multi-center, randomized, 12-month follow-up, non-inferiority study design
will be performed to evaluate the effectiveness and cost-effectiveness on
return to work of 40 hours versus 100 hours of vocational rehabilitation for
patients with subacute or chronic musculoskeletal pain and with sick leave from
work.

Reference 100 hours intervention:
The reference intervention is delivered over 15 weeks with two sessions (~3,5 h
/ session) per week. The reference intervention encompasses several modules:
return to work 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 program in the Netherlands; conducted by fourteen rehabilitation
centers, and of which four will participate in this study.

Experimental 40 hours intervention:
The experimental program lasts maximally 40 hours in 15 weeks. The experimental
intervention consists of return to work coordination (10 hours), 30 hours which
is dependent of the primary restriction of the client, and is a specific
program of multidisciplinary modules.

In case: 1) 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 program, compared with hours at work per
week pertaining to contract hours at baseline), and, 2) when the training team
expresses strong arguments that the patient will likely benefit from
elongation, the program will be elongated. However, this may occur in no more
than 5% of the cases.

There are no apparent risks for the participant being assessed by this study.