Table 2.

Mean (SD) change in disease specific scores at 2, 6, and 12 months from baseline for patients receiving physiotherapy or advice only for low back pain, with missing data replaced using last value carried forward

	Therapy group (n=144)		Advice only group (n=142)			P value*
Instrument	Mean (SD) change	Effect size	Mean (SD) change	Effect size	Mean difference (95% CI)	Analysis of covariance†	Repeated measures analysis of covariance†
Oswestry disability index:
2 months	−2.65 (9.34)	0.24	−1.33 (9.29)	0.12	−1.32 (−3.50 to −0.86)	0.20 (0.17)	0.24
6 months	−2.89 (11.59)	0.26	−1.83 (10.61)	0.17	−1.06 (−3.66 to 1.54)	0.36 (0.31)
12 months	−3.27 (10.99)	0.29	−2.23 (11.47)	0.20	−1.04 (−3.70 to 1.59)	0.33 (0.28)
Roland and Morris disability questionnaire:
2 months	−1.13 (3.98)	0.26	−0.56 (3.38)	0.13	−0.56 (−1.42 to 0.30)	0.20 (0.32)	0.46
6 months	−1.19 (4.74)	0.27	−0.79 (4.20)	0.18	−0.40 (−1.44 to 0.64)	0.45 (0.61)
12 months	−1.36 (4.66)	0.31	−0.99 (4.23)	0.23	−0.38 (−1.41 to 0.66)	0.48 (0.62)

^*t test.

^†Adjusted for score at baseline, age, sex, smoking status, and time since first episode of back pain.