Journal of Rehabilitation Medicine 51-4inkOmslag | Page 49

Return to work after interdisciplinary pain rehabilitation
Registered patients with
completed data from the
SQRP 2007-2011 and linked
with the SSIA database.
n=15,211
Registered patients
n=15,148
Patients enrolled in the
present study
n=7,297
Missing data from the SSIA
for one or more of the
periods under study (1 year
before (T0), at start (T1), at
1 (T2) and 2 years (T3)
after rehabilitation)
n=63
Excluded patient only
assessed, not enrolled in
MMR
n=7,851
Fig. 1. Inclusion process of study participants from Swedish Quality
Registry for Pain (SQRP) and Swedish Social Insurance Agency (SSIA).
days of work absence due to sickness. This meant that patients
with sick leave had at least 14 consecutive days of registration
at the SSIA database during any given period defined by this
study. Each patient was sequentially followed during a period
of 3 years: from 1 year prior MMR to 2 years after discharge.
In order to analyse changes in patterns of sick leave the se-
lected measurement points were defined as periods of time. To
analyse changes occurring before MMR, the 12-month period
prior to MMR was divided into trimesters. Two of these were
included in the statistical analyses. The first ranged from 365
to 273 days before the start of MMR (T0). The second ranged
from 90 to 0 days before the start (T1). The 1-year follow-up
measuring point was defined as a period ranging from 320 to
410 days after discharge from MMR (T2), and the measurement
point at 2 years follow-up was defined as a period ranging from
685 to 775 days after discharge from MMR (T3).
In this study, 4 categories of sick-leave benefits were con-
structed based on: (i) the extent of benefit (full-benefits, partial
benefits and no benefits) and (ii) the length or duration of sick
leave (temporary and/or permanent). The categories are des-
cribed below:
• full-time permanent sick leave (previously called disability
pension)
• full-time sick leave (including temporary or mixed temporary/
permanent full-time sick leave)
• partial sick leave from 25% to 75%
• no sick leave
Work ability should not be defined in terms of sick leave. This
study assumes that the degree of sick leave registered in SSIA
usually indicates the degree of absence from the workplace.
The category full-time permanent sick leave includes persons
assumed to be absent from work with permanent lack of working
ability or absent from work for more than 2 years. The category
full-time sick leave includes combinations of either only tem-
porary or combinations of temporary and permanent sick leave.
This category was created under the assumption that it included
persons with less deteriorated work ability than the category
full-time permanent sick leave. The category temporary sick
leave includes persons assumed to be without work ability for
up to a maximum of 2 years.
Data and statistical analysis
Descriptive data are presented as medians and 25 th –75 th per-
centiles for ordered categorical data. Differences in number of
283
patients in the 4 categories of sick leave within the sample over
time, at T1, T2 and T3, were analysed by Friedman’s analysis
of variance (ANOVA) by ranks. Wilcoxon signed-rank test was
used as post-hoc analysis and for analysis of difference between
groups at the different time-points and Mann–Whitney U test
within groups at different time-points.
SPSS for Windows version 24.0 was used for all statistical
analyses. The level of significance was set at p < 0.05.
Sex
Men and women were analysed separately in order to explore
and describe their patterns of sick leave.
Policy changes in the sick-leave benefit system
Participants in MMR were separated into 2 groups; one group
“before” policy changes, year 2007–08 (n = 16,02) and one
group “after” policy changes, year 2009–11 (n = 5,695). The
groups were analysed separately to examine whether policy
changes in sick-leave benefits affected the levels of sick leave for
patients registered in SQPR 2009–11 compared with 2007–08.
Ethics
This study followed the principles of the Declaration of Helsin-
ki, and the study was approved by the Regional Ethical Review
Board in Lund, Sweden (Dr 2018-31). The data were collected
as part of the ongoing quality control of clinical care activities
in the participating clinics, and stored with the consent of the
National Swedish Data Inspection Agency (permission number
1580-97). Informed consent was received and participation was
entirely voluntary.
RESULTS
Patients’ characteristics
The patients’ characteristics are shown in Table I. Most
patients (67%) were referred from primary care. One-
third of patients reported several pain locations, and
more than 50% reported mild or severe symptoms of
anxiety or depression according to HADS. Patients
also reported severe negative life interferences due to
pain (MPI).
Changes in extent of sick leave from 1 year before
multimodal rehabilitation to start of multimodal
rehabilitation
There was a significant change in the distribution of
sick-leave benefits among the participants during the
year before rehabilitation (p < 0.001), with a larger
percentage of full-time and partial sick leave and a
smaller percentage of no sick leave at T0 compared
with T1. Fig. 2 illustrates the percentage of patients
in the different categories of sick leave at the different
time-points.
J Rehabil Med 51, 2019