Urge incontinence: Estimating environmental and obstetrical risk factors using an identical twin study

Introduction and hypothesis: The objective of this study was to determine risk factors for urge urinary incontinence (UUI). Methods: A multi-item survey was administered to a community sample of identical twin sisters from 2002-2008. Generalized estimating equations accounting for cotwin correlation were used to perform three different regression models on the outcome: UUI (yes vs. no). Results: Mean age, median parity, and BMI were 41.4±16.4 (18-85), 1.0, and 26.0±6.5 (13.5-55.8), respectively. Thirty-five percent of women were post-menopausal, and 27.5% had UUI. Urge urinary incontinence was reported in 40.1% of parous versus 14.1% among nulliparous women (p<.0001). The rate of UUI was 40.6% after vaginal delivery, 36.7% after cesarean delivery, and 14.1% in nulliparous women (p<.0001). Obesity, age >40, and chronic constipation were also identified as risk factors for urge urinary incontinence. Conclusion: Risk factors for UUI include parity, age, obesity, and chronic constipation. There was a 2.5-fold increased risk of UUI after one or more births, regardless of type of delivery.