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This led to increasing levels of SMDs during the
course, since they quantify the differences of the score
changes between GSP and ISP. However, adjustment
for the confounders attenuated those differences during
the course. For example, on Bodily pain, the observed
score changes (listed above) led to bivariate, unad-
justed SMDs of –0.093 (T1)/0.324 (T2)/0.429 (T3),
but 0.055/0.502/0.465 multivariate, adjusted SMDs
in sample 1. The differences on Bodily pain in sample
2 were not statistically significant; the adjusted SMD
at baseline was –0.030 (p = 0.868) and increased to
a SMD of 0.263 (p = 0.141). The same was true for
Social functioning.
Significant change differences between GSP and
ISP in sample 1 at each follow-up measurement were
seen on the following scales: Role physical (adjusted
SMD=0.572, 0.413, 0.404 for T1 to T3), Vitality
(0.598, 0.577, 0.612), and Social functioning (0.408,
0.450, 0.371). In sample 2, Physical functioning
(adjusted SMD = 0.543, 0.491 for T1 and T4), Role
physical (0.531, 0.558), General Health (0.712, 0.441),
Vitality (0.429, 0.479), and Role emotional (0.473,
0.473) showed significant differences.
In total, 5 of 8 SMDs were statistically significant
(p ≤ 0.027) in both samples at discharge and at the
3-month follow-up. At the 6-month follow-up in sam-
ple 1, 7 SMDs (p ≤ 0.045) and at 1-year follow-up, 6
SMDs (p ≤ 0.012) were statistically significant.
Of the total of 8 health dimensions, 5 showed
significant differences at discharge, 5 at the 3-month
follow-up, and 7 at the 6-month follow-up in sample
1. In sample 2, the corresponding numbers were 5
(discharge) and 6 (12-month follow-up).
DISCUSSION
This study compared short- and mid-term changes in
the biopsychosocial health and quality of life of ISP
with GSP with chronic pain before and after a stan-
dardized IPMP. GSP improved in all measured scales
at discharge and the effects remained almost stable in
the follow-up measurements. In contrast, ISP showed
less improvement on most scales at discharge and lost
these positive effects completely over time.
These score change differences resulted in statisti-
cally significant adjusted SMDs on Role physical and
Vitality, as well as, although somewhat less on General
health over the course. At the mid-term follow-ups
(6 and 12 months), all but one of the scales showed
significant differences in favour of the GSP. These
prominent differences cannot be explained by dif-
ferences in therapy because both groups underwent
the same structured standardized IPMP held in the
specific language.
www.medicaljournals.se/jrm
The main focus of the study was to explore possible
differences between GSP and ISP. The naturalistic de-
sign of the study is one of the factors that led to baseline
differences. The design of the study did not allow us
to draw causal conclusions that explain the differences
in the score changes of the 2 groups, the SMDs. Some
cofactors may be found in the sociodemographic and
disease-related characteristics (Table I), and some
in parameters that were not assessed (e.g. sickness
benefits from the insurance). Some can be found in
existing literature: ethnicity including cultural, beha-
vioural and attitudinal norms and systems of meaning
(5, 30, 31) and socioeconomic level (4, 5) including
educational level and work status. For the 3 most re-
levant confounders, sex, education and baseline score,
analysis of the differences was adjusted by multivariate
regression analysis. All 3 cofactors are well-known to
affect and confound the outcome by epidemiological
reasons and showed the biggest differences between
the 2 groups at baseline. Even after correction of the
unequal distributions of those 3 cofactors, substantial
and statistically significant differences in outcome were
observed between the 2 groups.
Although language has been described as “a proxy
for acculturation” and as “a significant marker of
cultural identity”, empirical data to support this are
lacking (32). An improving knowledge of the German
language in combination with an increasing length
of stay in a German-speaking region is assumed to
enhance the level of acculturation (33). This means
that attitudes, values, customs, beliefs, and (health)
behaviours are adapted to another culture and the
influence of the origin culture diminishes (33–35). It
can be assumed that migrants who have acquired high
levels of language skills are also well acculturated in
other cultural dimensions. Therefore, cultural diffe-
rences within the German-speaking group of patients
are thought to be small and of minor importance for
health status and healthcare utilization, independent
of migration status.
It has been suggested that disparities in pain among
racial and ethnic minorities may be influenced not only
by the patient, but also by the healthcare provider and
the healthcare system (2). In Switzerland, healthcare
insurance is mandatory and all patients have equal
access to the healthcare system. Nevertheless, lower
levels of acculturation and no German language
knowledge influenced the accessibility and use of the
healthcare system (36).
A comparable study examined Italian migrant wor-
kers (n = 36) and Swiss GSP (n = 49) with chronic low
back pain (37). Both groups underwent an identical
3-month outpatient treatment programme in different
languages. The levels of state and change in physical