Abstract: We included two studies (involving a total of 49 women). Each study compared yoga to a different comparator, therefore we were unable to combine the data in a meta-analysis. A third study that has been completed but not yet fully reported is awaiting assessment. One included study was a six-week study comparing yoga to a waiting list in 19 women with either urgency urinary incontinence or stress urinary incontinence. We judged the certainty of the evidence for all reported outcomes as very low due to performance bias, detection bias, and imprecision. The number of women reporting cure was not reported. We are uncertain whether yoga results in satisfaction with cure or improvement of incontinence (risk ratio (RR) 6.33, 95% confidence interval (CI) 1.44 to 27.88; an increase of 592 from 111 per 1000, 95% CI 160 to 1000). We are uncertain whether there is a difference between yoga and waiting list in condition-specific quality of life as measured on the Incontinence Impact Questionnaire Short Form (mean difference (MD) 1.74, 95% CI -33.02 to 36.50); the number of micturitions (MD -0.77, 95% CI -2.13 to 0.59); the number of incontinence episodes (MD -1.57, 95% CI -2.83 to -0.31); or the bothersomeness of incontinence as measured on the Urogenital Distress Inventory 6 (MD -0.90, 95% CI -1.46 to -0.34). There was no evidence of a difference in the number of women who experienced at least one adverse event (risk difference 0%, 95% CI -38% to 38%; no difference from 222 per 1000, 95% CI 380 fewer to 380 more). The second included study was an eight-week study in 30 women with urgency urinary incontinence that compared mindfulness-based stress reduction (MBSR) to an active control intervention of yoga classes. The study was unblinded, and there was high attrition from both study arms for all outcome assessments. We judged the certainty of the evidence for all reported outcomes as very low due to performance bias, attrition bias, imprecision and indirectness. The number of women reporting cure was not reported. We are uncertain whether women in the yoga group were less likely to report improvement in incontinence at eight weeks compared to women in the MBSR group (RR 0.09, 95% CI 0.01 to 1.43; a decrease of 419 from 461 per 1000, 95% CI 5 to 660). We are uncertain about the effect of MBSR compared to yoga on reports of cure or improvement in incontinence, improvement in condition-specific quality of life measured on the Overactive Bladder Health-Related Quality of Life Scale, reduction in incontinence episodes or reduction in bothersomeness of incontinence as measured on the Overactive Bladder Symptom and Quality of Life-Short Form at eight weeks. The study did not report on adverse effects. We identified few trials on yoga for incontinence, and the existing trials were small and at high risk of bias. In addition, we did not find any studies of economic outcomes related to yoga for urinary incontinence. Due to the lack of evidence to answer the review question, we are uncertain whether yoga is useful for women with urinary incontinence. Additional, well-conducted trials with larger sample sizes are needed.

Plain-language summary: We found two studies involving a total of 49 women. One was a six-week study comparing yoga to a waiting list (delayed treatment) in women with either stress or urgency urinary incontinence. The other was an eight-week study comparing yoga to mindfulness-based stress reduction (MBSR) in women with urgency urinary incontinence. We also identified an ongoing study involving 50 women that aims to compare yoga with stretching; we will include this study when the results are reported. The trial comparing yoga to a waiting list did not report the number of women reporting cure but did report on symptoms, condition-specific quality of life and adverse effects. While this comparison generally favoured the yoga intervention, we are uncertain whether yoga improves urinary incontinence due to the very low certainty of the evidence. There was no difference between groups in the number of women reporting an adverse event and no serious adverse events were reported, but we are uncertain whether yoga increases harms as the certainty of the evidence is very low. The trial comparing yoga to MBSR reported on symptoms and condition-specific quality of life but did not report the number of women reporting cure. While this comparison generally favoured the MBSR intervention, we are uncertain whether yoga improves urinary incontinence due to the very low certainty of the evidence. There was no information on adverse events. We did not find any information on the value for money of yoga for urinary incontinence. Although we identified some evidence on yoga treatment for treating urinary incontinence in women, the included studies were very small and there were issues with the way they were conducted, which limits our confidence in the results. Due to the nature of the treatments, the participants and staff of the trial comparing yoga to a waiting list were aware of which groups the participants were assigned and it is possible that the women in the yoga group reported some benefits because they expected yoga to be helpful. The trial comparing yoga to MBSR did not intend to test yoga as a treatment for incontinence. Instead, the trial tested MBSR as a treatment and used yoga classes to ensure that women in the comparison group received attention from the study staff. In addition, the trial comparing yoga to MBSR did not collect outcomes on all women and it is possible that the women who reported outcomes had either better or worse results than the women who did not report outcomes. There is currently insufficient good-quality evidence to judge whether yoga is useful for women with urinary incontinence.