Table 1 Background data for the two groups at baseline assessment. Note that only a selection of patients later participated in IPRP. For categorial variables, we report the results of Chi² test and for continuous variables t-test for independent groups* denotes significant group difference

Sex (% men)

22.6

40.6

 < 0.001*

NA

Born outside Europe (%)

13.1

14.6

0.082

NA

University education (%)

22.3

22.7

0.702

NA

High healthcare consumption (≥ 4 physician visits; %)

69.3

73.9

 < 0.001*

NA

Age (Mean ± SD)

42.8 ± 11.0

45.2 ± 11.0

 < 0.001*

-0.22

Not work (days, Mean ± SD)

1393 ± 2592

1431 ± 2742

0.715

-0.02

Pain duration (days, Mean ± SD)

3332 ± 3391

2620 ± 3182

 < 0.001*

0.21

Persistent pain duration (days, Mean ± SD)

2656 ± 3015

2136 ± 3125

 < 0.001*

0.17

PRI (Mean ± SD)

16.0 ± 9.2

11.3 ± 7.2

 < 0.001*

0.53