Effectiveness of physical training for self-employed persons with musculoskeletal disorders: a randomized controlled trial

Table 2 Results of the univariate and multivariate survival analyses regarding claim duration (days)

			Univariate analyses		Adjusted Hazard Ratios (95% confidence interval) for return to work (Cox regression analyses) †
			Claim duration (days) (median (IQR))*	Log rank (p)	HR	p-value
6 months	PT (n = 101)	Intervention	181 (119 – 184)
		Control	153 (48 – 181)	0.03	0.5 (0.3 – 0.9)	0.03
	PTCBWE (n = 153)	Intervention	133 (70 – 183)
		Control	137 (48 – 181)	0.60	0.8 (0.5–1.3)	0.43
12 months	PT (n = 101)	Intervention	228 (122 – 365)
		Control	165 (48 – 365)	0.18	0.7 (0.4 – 1.1)	0.12
	PTCBWE (n = 153)	Intervention	148 (75 – 343)
		Control	137 (48 – 365)	0.95	0.9 (0.6 – 1.4)	0.72

* Gross duration in days.
IQR indicates interquartile range (25th – 75th percentile).
† Adjusted for general health and duration of disability before randomization.
PT indicates physical training without a cognitive behavioral component and workplace specific exercises. PTCBWE indicates physical training with a cognitive behavioral component and workplace specific exercises.
In the univariate analyses Cox regression was used to determine the difference in claim duration in days between randomization and 6 and 12 months follow-up (primary outcome measure) among both study groups (main exposure). The control group (participants not randomized for physical training) served as the reference category. The multivariate analyses were the same but with a correction for two possible confounders: 'general health' and 'duration of disability before randomization'.

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