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

Abstract

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.

Figure 1

Poses used in hatha yoga protocol for chronic low back pain.

Figure 2

Participant flow diagram. *Other reasons for ineligibility: alcohol abuse (6), low back surgery within 3 years (4), specific LBP pathology (4), pregnancy (3), unexplained weight loss (2), drug abuse (1), being wheelchair dependent (1), and unwilling to travel (1). ^†Participants randomized to either once-weekly or twice-weekly groups could participate in any of the 17 yoga classes.

Figure 3

Mean pain and RMDQ scores over time, by randomly assigned group. Results are unadjusted; adjustment for potential confounders (race, education, cLBP duration, satisfaction with previous back care, history of yoga use, and baseline outcome measurements) resulted in essentially similar findings. Bars indicate 95% confidence intervals. RMDQ: modified Roland Morris Disability Questionnaire (0–23 with higher scores reflecting worse back pain-related function). (a) Mean low back pain intensity in the previous week on an 11-point numerical rating scale. (b) Mean RMDQ scores.

Figure 4

Pain medication use over time, by randomly assigned group. Height of bars indicates percentage of participants reporting any use within the previous week. NSAIDs: nonsteroidal anti-inflammatory drugs.

Figure 5

Dose-response relationship between yoga classes attended and change in primary outcomes, entire sample. (a) Yoga class attendance and change in mean low back pain intensity from baseline to week 12. (b) Yoga class attendance and change in mean RMDQ score from baseline to week 12.