Manual therapy followed by specific active exercises versus a placebo followed by specific active exercises on the improvement of functional disability in patients with chronic non specific low back pain: a randomized controlled trial

Table 3 Results of mixed models for primary outcomes

Outcome	Predictors	Coeff	95% CI	P
Immediate effect on pain (base line = before each session)
VAS-pain Immediate effect	Intervention	−0.76	[−1.22;-0.30]	0.001*
	Time	0.02	[−0.03;0.06]	0.484
	Pain baseline	−0.27	[−0.33;-0.20]	<0.001
	Constant	0.81	[0.29;1.33]	0.002
Treatment effect on time (base line = before treatment)
VAS-pain Average 24 hour	Treatment	−1.24	[−2.37;-0.11]	0.032
	Time	−0.20	[−0.69;0.29]	0.426
	Pain baseline	0.43	[0.17;0.69]	0.001
	Constant	1.68	[−0.37;3.73]	0.108
ODI	Treatment	−7.14	[−12.80;-1.52]	0.013*
	Time	−1.80	[−3.92;0.33]	0.097
	ODI baseline	1.95	[1.50;2.39]	<0.001
	Constant	0.40	[−7.88;8.68]	0.924

* Statistical significance for primary outcomes (P < 0.025).
Since the time by treatment interactions were not statistically significant, the analyses were repeated after dropping the interaction terms.
Coeff = regression coefficients: same interpretation as for ordinary (least square) regression.
CI = confidence intervals; VAS-pain, Visual Analogue Scale of pain; ODI, Oswestry Disability Index.
VAS-pain (immediate effect) was the pain difference before and after each session, and time was the number of the 8 therapeutic sessions.
VAS-pain (average 24 hour) and ODI were calculated over time, i.e., before (baseline) and after the 8^th therapeutic session, as well as at 3 and 6 months after the end of the treatment.

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