Body mass index, abdominal fatness, weight gain and the risk of urinary incontinence: a systematic review and dose–response meta‐analysis of prospective studies

Background Adiposity has been associated with elevated risk of urinary incontinence in epidemiological studies; however, the strength of the association has differed between studies. Objectives To conduct a systematic literature review and dose–response meta‐analysis of prospective studies on adiposity and risk of urinary incontinence. Search strategy We searched PubMed and Embase databases up to 19 July 2017. Selection criteria Prospective cohort studies were included. Data collection and analysis Data were extracted by one reviewer and checked for accuracy by a second reviewer. Summary relative risks ( RR s) and 95% confidence intervals ( CI s) were calculated using random effects models. Main results Twenty‐four prospective studies were included. The summary RR per 5 kg/m 2 increment in body mass index (BMI) was 1.20 (95% CI 1.16–1.25, I 2 = 62%, n = 11) for population‐based studies and 1.19 (95% CI 1.08–1.30, I 2 = 87.1%, n = 8) for pregnancy‐based studies, 1.18 (95% CI 1.14–1.22, I 2 = 0%, n = 2) per 10 cm increase in waist circumference and 1.34 (95% CI 1.11–1.62, I 2 = 90%, n = 2) per 10 kg of weight gain. Although the test for nonlinearity was significant for BMI , P = 0.04, the association was approximately linear. For subtypes of urinary incontinence the summary RR per 5 BMI units was 1.45 (95% CI 1.25–1.68, I 2 = 85%, n = 3) for frequent incontinence, 1.52 (95% CI 1.37–1.68, I 2 = 34%, n = 4) for severe incontinence, 1.33 (95% CI 1.26–1.41, I 2 = 0%, n = 8) for stress incontinence, 1.26 (95% CI 1.14–1.40, I 2 = 70%, n = 7) for urge incontinence, and 1.52 (95% CI 1.36–1.69, I 2 = 0%, n = 3) for mixed incontinence. Conclusion These results suggest excess weight may increase risk of urinary incontinence. Tweetable abstract Overweight and obesity increase the risk of urinary incontinence.