Occupational rehabilitation for musculoskeletal and mental disorders
same outpatient programme (hereafter referred to as the long
inpatient and outpatient programme, respectively). The primary
outcome was sickness absence days. The study protocol and
results from one of the randomized trials have been published,
and the description of the methods is partly overlapping with
previous studies (12, 13, 15). The study was approved by the
Regional Committee for Medical and Health Research Ethics
in Central Norway (no.: 2012/1241), and is registered in clini-
caltrials.gov (no.: NCT01926574).
Eligible participants were aged 18–60 years, and sick listed
2–12 months with a diagnosis within the musculoskeletal (L),
psychological (P) or general and unspecified (A) chapters of
the International Classification of Primary Care, second edition
(ICPC-2). The current sick-leave status at inclusion had to be at
least 50% off work. Sick-listed individuals fulfilling the inclu-
sion criteria were identified in the Social Security Registry and
randomized to receive an invitation to either the long or the short
trial. Invited participants completed a short initial questionnaire
assessing eligibility. Those eligible were invited for an outpa-
tient screening assessment. Exclusion criteria were: (i) alcohol
or drug abuse; (ii) serious somatic (e.g. cancer, unstable heart
disease) or psychological disorders (e.g. high risk of suicide,
psychosis, ongoing manic episode); (iii) disorders requiring
specialized treatment; (iv) pregnancy; (v) currently participating
in another treatment or rehabilitation programme; (vi) insuf-
ficient oral or written Norwegian language skills to participate
and benefit from group sessions and complete questionnaires;
(vii) scheduled for surgery within the next 6 months; or (viii)
serious problems with functioning in a group setting.
Ethical approval.
All procedures performed in studies involving human parti-
cipants were in accordance with the ethical standards of the
institutional and/or national research committee and with the
1964 Declaration of Helsinki and its later amendments or com-
parable ethical standards. Informed consent was obtained from
all individual participants included in the study.
Rehabilitation programmes
The inpatient programmes consisted of group-based acceptance
and commitment therapy (ACT) (16), a form of cognitive beha-
vioural therapy (third-generation), individual and group-based
physical training, mindfulness, education on various topics,
and individual meetings with the coordinators in work-related
problem-solving sessions and creating a RTW plan. One pro-
gramme lasted 3.5 weeks and the other 4+4 days (with 2 weeks
at home in-between).
The outpatient programme, which was identical in the 2
trials, consisted mainly of group-based ACT once a week for 6
weeks, each session lasting 2.5 h. The common component for
the inpatient and outpatient programmes was ACT, in which
the aim was to facilitate RTW through increased psychological
flexibility (17), which presumably would increase self-efficacy
and RTW expectations. A more detailed description of the pro-
grammes has been published previously (12).
Outcomes
Questionnaires. Self-reported data on fear-avoidance beliefs and
other questionnaires were collected via web-based questionnaires
answered at screening before inclusion (baseline, T0), at the start
(T1) and the end of the programme (T2), and at 3 months (T3)
and 12 months (T4) of follow-up after the end of the programmes.
177
Fear-avoidance beliefs were recorded using the FABQ (4). It
consists of 2 subscales: (i) a 7-item work subscale (FABQ-Work,
range 0–42 points), and (ii) a 4-item physical activity subscale
(FABQ-Physical activity, range 0–24 points). To make the
questionnaire usable for participants with other complaints than
back pain, “complaints” replaced “pain” and “body” replaced
“back”. There are no established cut-offs for minimal detectable
change in FABQ, but 12 points have been suggested for the work
subscale and 9 for the physical activity subscale (18).
Other variables registered by questionnaires at the start of
the rehabilitation programmes were anxiety and depression
symptoms (measured using the Hospital Anxiety and Depression
scale (HADS) (19)), mean pain last week, level of completed
education (dichotomized as high (college/university) or low) and
employment status (dichotomized as having a current job, or not).
Sick-leave register data
Sick leave was measured using data from the Norwegian Natio-
nal Social Security System Registry. All individuals receiving
any form of sickness or disability benefits in Norway are regis-
tered by their social security number. The data consisted of all
individual registrations of periods with any medical benefits.
Work participation was measured as the number of days not
receiving medical benefits during 9 months of follow-up after
the end of the rehabilitation programmes. It was adjusted for
graded sick leave, employment fraction, and calculated as a
5-day work-week, yielding 196 possible working days.
Randomization and blinding
If the outpatient screening was passed, the second randomization
allocated the participant to either the inpatient or the outpatient
programme (Fig. 1). A project co-worker performed the first
randomization. In the second allocation, a flexibly weighted
randomization procedure was provided by the Unit of Applied
Clinical Research (third-party) at the Norwegian University of
Science and Technology (NTNU), to ensure that the rehabilita-
tion centre had enough participants to run monthly groups in
periods of low recruitment.
It was not possible to blind the participants or the caregivers
for treatment. The researchers were not blinded.
Statistical analysis
Sample size was calculated based on the primary outcome, i.e.
number of sickness absence days, resulting in 80 persons in
each arm (12).
Linear mixed-effects models were used to compare scores
on the FABQ-work and physical activity subscale over time
between the inpatient and outpatient programme, separately for
the 2 trials. In addition to programme and time, an interaction
term between programme and the 5 time-points (T0–T4) was
included in the analyses to assess whether the effects of the
programmes differed over time. A random intercept for person
was included in the models to allow the participants to start at
different levels. The main analyses were not adjusted for ba-
seline characteristics, but the sensitivity analysis was adjusted
for sex, age and education level to assess the robustness of the
results. In a second sensitivity analysis, a per protocol analysis
was performed, excluding participants who withdrew after
randomization and/or attended less than 60% of the sessions
in the outpatient programmes.
To assess whether changes in fear-avoidance beliefs during
rehabilitation were associated with work-participation days
J Rehabil Med 51, 2019