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Table 6 Subgroup analyses: differences in treatment effects between subgroups (statistical test of interaction)

From: Feasibility and long-term efficacy of a proactive health program in the treatment of chronic back pain: a randomized controlled trial

Primary outcomes Subgroups
Low risk (0–3) IG versus CG Medium/High risk (> 3) IG versus CG
Back pain severity (CPGQ) characteristic back pain intensity (0–100) Mean Difference (SE) between IG / CG - 1.0 (2.17) + 7.4 (2.69)
Δ of treatment effect in the both subgroups (SE) 8.4 (3.46)
z-score/ p 2.428/ 0.015
disability points (0–6) mean difference (SE) between IG / CG 0.05 (0.22) 0.68 (0.28)
Δ of treatment effect in the both subgroups (SE) 0.63 (0.36)
z-score/ p 1.750 / 0.080
Health-related quality of life (SF-12) physical component (0–100) mean difference (SE) between IG / CG 0.9 (1.10) 3.9 (1.34)
Δ of treatment effect in the both subgroups (SE) 3.0 (1.73)
z-score/ p 1.734 / 0.083
mental component (0–100) mean difference (SE) between IG / CG - 2.1 (1.38) 2.7 (1.60)
Δ of treatment effect in the both subgroups (SE) 4.8 (2.11)
z-score/ p 2.275/ 0.023
  1. CPGQ Chronic Pain Grade Questionnaire according to v. Korff, SF-12 12 Items Short Form questionnaire, SE standard error, Δ: difference, p significance value