Journal of Rehabilitation Medicine 51-4inkOmslag | Page 53

Return to work after interdisciplinary pain rehabilitation
year before to 2 years after MMR, which in agreement
with other findings (22, 24–26).
The current results were achieved in a national popu-
lation of patients with chronic pain with reported com-
plex and negative pain-related consequences, involving
psychological, social, and activity-related problems, as
illustrated by the demographic and background data.
Compared with the participants in studies by Busch
et al. (22) and Jensen et al. (6), the participants in the
current study had longer duration of pain and more
complex emotional disturbances.
Analyses of aggregated sick-leave data at different
time-points, without discerning how sick leave changes
both in type and extent of benefit for each individual,
may fail to apprehend important variations that, at the
individual level, are crucial for patients regaining areas
of autonomy and increased activity. For example, the
proportion of patients in the full-time permanent sick
leave category at T1, T2 and T3 appears to be stable
over time, at 11–12%. It might then, erroneously, be
argued that MMR has no RTW effect in this group.
Our analyses showed that this is not the case. On the
contrary, MMR seems to be associated mainly with
positive changes in all sick-leave groups, including the
full-time permanent sick leave category. Even though
the share is stable, the patients in the category are not
the same at the different time-points. Approximately
30% of patients in the full-time permanent sick leave
category prior to MMR were in the no-sick leave ca-
tegory 2 years after MMR, indicating that almost one-
third of the patients that started MMR in the full-time
permanent sick leave category were no longer on sick
leave at all. On the other hand, 10% of patients in the
full-time sick leave (temporary or mixed temporary
and permanent) category prior to MMR shifted to the
full-time permanent sick leave category 2 years after
MMR, suggesting that, as many clinicians would
claim, MMR may be effective in stopping fruitless
rehabilitation efforts for individuals who are not able
to return to work. To our knowledge, there are no other
studies reporting similar analyses.
In this study, the patterns of sick leave changed
significantly for both women and men, but when ana-
lysing sex differences at different time-points, it was
found that men changed to a more favourable category
of sick leave and, hypothetically, gained more from
MMR. Sex has earlier been found to significantly
influence the risk of full-time permanent sick leave
10 years after rehabilitation; women having a relative
higher risk than men of being on permanent disability
pension (22). When studying the long-terms effects
of rehabilitation on RTW for patients with back pain,
women benefitted the most after 3 years (6), but after
10 years no differences were found between men and
287
women. Our patients represent a wide range of diagno-
ses, from local to widespread pain, and this may have
influenced the outcome.
The social insurance system in Sweden underwent
major changes in 2008. According to Anema et al. (3),
these changes probably influence patterns of RTW, and
therefore some differences in patterns of sick leave due
to policy changes were expected in this study. Thus,
we controlled for the policy changes in the sickness
benefit system, by analysing data in both periods se-
parately, before and after implementation of the new
regulations. The results indicate that the regulatory
changes in the benefit system entailed a positive change
in reducing levels of sick leave, corroborating findings
from previous research on the impact of regulation and
law changes in benefit levels in RTW (3, 27). Further-
more, the regulatory changes might have impacted on
decisions about referral to MMR, as some differences
were found between the groups regarding duration of
pain, levels of anxiety and life control. Nevertheless,
the positive changes in sick-leave benefits after re-
habilitation were significant for both periods, before
and after policy changes, indicating that MMR per se
had an impact on the patients’ patterns of sick leave,
in addition to policy changes.
Methodological considerations
This study analysed sick-leave benefits by linking
information from SQRP to data from a national insu-
rance agency database (SSIA). Data from the SSIA
on sick-leave benefits is more valid than self-reported
data (7) and probably more reliable. This study is, to
our knowledge, the first attempt to publish sick-leave
data on a national level from specialized pain rehabi-
litation units. The large number of patients included
(n = 7,297) and the geographical spread make the data
highly representative for this patient group over the
whole country. Previous studies often have transfor-
med patients’ different uses of sick-leave benefits into
the total number of days of sick leave (22, 28, 29).
We intended to analyse the extent and length of sick
leave through an extended timeline in a large sample
of patients undergoing MMR by selecting specific
time periods prior to and after MMR. However, due
to methodological differences between the current and
previous studies, comparisons were not feasible. We
would argue that the methods used elucidate different
aspects of the sick-leave spectrum; ours focussing on
processes, and others focussing on total amounts.
This is not a controlled design study, thereby ge-
neralization of the results is limited. The effect of
rehabilitation on sick-leave benefit levels can therefore
not be fully established. On the other hand, the sample
size, the large period under observation, and the fre-
J Rehabil Med 51, 2019