Background: Bikram yoga is a form of heated yoga (HY) in which participants complete 26 postures and 2 breathing exercises in a room heated to 105°F. HY is a potential treatment option for depression. There is limited research on predictors of participant dropout in randomized controlled trials of all types of yoga. To address this gap, we analyzed several factors that are believed to impact study completion.
Methods: Patients were randomized to either an 8-week HY intervention or a waitlist control, after which the latter completed 8 weeks of HY. During the HY portion, participants were encouraged to attend at least two 90-minute classes per week. The outcome variable for this analysis was completion status, defined as attending the final study assessment visit (prior to the 1- month follow-up portion of the study). Predictor variables included: sex, age, ethnicity, race, education level, income, religious beliefs, yoga history, state and trait anxiety, screening and baseline severity of depression and anxiety, and perceived stress. Multiple binomial logistic regressions were conducted using SPSS (Version 24).
Results: Of the 87 participants, 47 completed the study across both the active and waitlist conditions. Binary logistic regression indicated that there was a significant association between completion status and perceived stress levels at time of screen, X2(1) = 5.195, p = .023. Other predictor variables were not significantly related to completion status.
Conclusions: Surprisingly, the only significant predictor of completion status was perceived stress levels at screening, indicating that participants with higher initial stress levels were less likely to complete the study. Further studies should replicate this finding and explore how socioeconomic status and other factors affect participants’ completion status in randomized controlled trials of non-heated and heated yoga.