Comparing Once- versus Twice-Weekly Yoga Classes for Chronic Low Back Pain in Predominantly Low Income Minorities: A Randomized Dosing Trial

Table 4

Outcome measurements at 6 and 12 weeks.

Outcome measure	Mean baseline value (SD)	Mean change from baseline (95% CI)
		6 weeks	𝑃 value	12 weeks	𝑃 value
Pain
Once-weekly classes	7.1 (1.4)	−1.8 (−2.5 to −1.2)∗		−2.1 (−2.9 to −1.3)∗
Twice-weekly classes	6.7 (1.8)	−1.5 (−2.1 to −1.0)∗		−2.4 (−3.1 to −1.8)∗
Between-group difference in means		−0.3 (−1.1 to 0.6)	0.49	0.3 (−0.2 to 0.8)	0.62
RMDQ
Once-weekly classes	13.7 (4.8)	−4.4 (−6.0 to −2.8)∗		−5.1 (−7.0 to −3.2)∗
Twice-weekly classes	13.6 (5.2)	−3.8 (−5.2 to −2.4)∗		−4.9 (−6.5 to −3.3)∗
Between-group difference in means		−0.6 (−2.7 to 1.6)	0.62	−0.1 (−1.4 to 1.2)	0.83
SF-36 Physical
Once-weekly classes	37.5 (7.4)	6.7 (4.1 to 9.4)∗		6.4 (3.6 to 9.2)∗
Twice-weekly classes	37.4 (7.9)	5.1 (3.2 to 7.0)∗		6.3 (4.1 to 8.4)∗
Between-group difference in means		1.6 (−1.6 to 4.9)	0.33	0.2 (−3.4 to 3.7)	0.93
SF-36 Mental
Once-weekly classes	44.8 (12.4)	4.8 (1.9 to 7.7)^†		4.0 (1.3 to 6.7)^‡
Twice-weekly classes	44.1 (13.1)	2.6 (−0.4 to 5.6)		2.5 (−0.7 to 5.7)
Between-group difference in means		2.2 (−1.9 to 6.3)	0.29	1.5 (−2.6 to 5.6)	0.47

All analyses are unadjusted and performed using the intent to treat principle. After controlling for potential confounders (race, education, duration of chronic low back pain, satisfaction with previous back care, and previous yoga use) and baseline outcome measurements, adjusted results were nearly identical to the unadjusted results.
Abbreviations: SD: standard deviation; RMDQ: modified Roland Morris Disability Questionnaire; SF-36: the Short Form-36 Health Survey.
^∗𝑃<0.0001 for within-group difference compared to baseline.
^†𝑃=0.002 for within-group difference compared to baseline.
^‡𝑃=0.005 for within-group difference compared to baseline.