Table 1 Baseline characteristics of the study population, stratified by study arm, multimorbidity status and number of co-occurring MSK pain sites
Variable | Multimorbidity | No. of co-occurring MSK pain sites | ||||||
|---|---|---|---|---|---|---|---|---|
No (n = 149) | Yes (n = 312) | 0-1 (n = 190) | 2+ (n = 271) | |||||
Usual care (n = 68) | selfBACK (n = 81) | Usual care (n = 161) | selfBACK (n = 151) | Usual care (n = 89) | selfBACK (n = 101) | Usual care (n = 140) | selfBACK (n = 131) | |
Age, mean (SD), years | 42.1 (13.9) | 42.4 (13.0) | 48.7 (14.2) | 51.4 (15.1) | 45.4 (15.6) | 48.0 (14.7) | 47.6 (13.6) | 48.5 (15.3) |
Women, % | 50.0 | 44.4 | 62.1 | 56.3 | 49.4 | 47.5 | 64.3 | 55.7 |
Education: > 12 years, % | 61.8 | 69.1 | 64.0 | 63.6 | 66.3 | 72.3 | 61.4 | 60.3 |
Multimorbidity, % | – | – | – | – | 34.2 | 35.8 | 65.8 | 64.2 |
Co-occurring MSK pain (2+), % | 24.3 | 25.9 | 75.7 | 74.1 | – | – | – | – |
Pain duration | Â | Â | Â | Â | Â | Â | Â | Â |
 ≤ 4 weeks, % | 32.3 | 24.7 | 20.5 | 25.1 | 28.1 | 29.7 | 21.5 | 21.4 |
 5–12 weeks, % | 10.3 | 19.8 | 19.3 | 17.9 | 15.7 | 20.8 | 17.1 | 16.8 |
 > 12 weeks, % | 57.4 | 55.5 | 60.2 | 57.0 | 56.2 | 49.5 | 61.4 | 61.8 |
Pain intensity, mean (SD), NRS 0–10 | 4.5 (2.0) | 4.6 (1.9) | 5.1 (1.8) | 5.0 (2.0) | 4.9 (2.0) | 4.6 (1.9) | 5.0 (1.8) | 5.0 (2.0) |
Work ability index, mean (SD), 0–10 | 6.9 (1.8) | 6.8 (2.2) | 6.6 (1.8) | 6.6 (1.8) | 6.6 (1.9) | 6.9 (2.0) | 6.7 (1.8) | 6.5 (1.9) |
Body mass index, mean (SD), kg/m2 | 25.9 (4.3) | 27.3 (4.6) | 28.6 (5.6) | 27.4 (4.8) | 26.5 (4.6) | 26.9 (4.6) | 28.6 (5.7) | 27.7 (4.9) |
Physical activity | Â | Â | Â | Â | Â | Â | Â | Â |
 Sedentary/some physical activity, % | 51.5 | 46.9 | 64.6 | 63.0 | 53.9 | 55.5 | 65.0 | 58.8 |
 Regular/hard physical activity, % | 48.6 | 53.1 | 35.4 | 37.0 | 46.1 | 44.5 | 35.0 | 41.2 |