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

Background. Previous studies have demonstrated that once-weekly yoga classes are effective for chronic low back pain (cLBP) in white adults with high socioeconomic status. The comparative effectiveness of twice-weekly classes and generalizability to racially diverse low income populations are unknown. Methods. We conducted a 12-week randomized, parallel-group, dosing trial for 95 adults recruited from an urban safety-net hospital and five community health centers comparing once-weekly (n = 49) versus twice-weekly (n = 46) standardized yoga classes supplemented by home practice. Primary outcomes were change from baseline to 12 weeks in pain (11-point scale) and back-related function (23-point modified Roland-Morris Disability Questionnaire). Results. 82% of participants were nonwhite; 77% had annual household incomes <$40,000. The sample's baseline mean pain intensity [6.9 (SD 1.6)] and function [13.7 (SD 5.0)] reflected moderate to severe back pain and impairment. Pain and back-related function improved within both groups (P < 0.001). However, there were no differences between once-weekly and twice-weekly groups for pain reduction [−2.1 (95% CI −2.9, −1.3) versus −2.4 (95% CI −3.1, −1.8), P = 0.62] or back-related function [−5.1 (95% CI −7.0, −3.2) versus −4.9 (95% CI −6.5, −3.3), P = 0.83]. Conclusions. Twelve weeks of once-weekly or twice-weekly yoga classes were similarly effective for predominantly low income minority adults with moderate to severe chronic low back pain. This trial is registered with ClinicalTrials.gov NCT01761617.