Purpose: Previous studies have shown an association between urinary incontinence and increased mortality independently of demographics and health status. However, they do not account for the effect of frailty as a state of vulnerability. We evaluated whether there is an association between urinary incontinence and mortality and, if so, whether adjustment for a frailty index would affect the association.
Materials and methods: We performed a cross-sectional study in a nationally representative sample of 2,282 community dwelling individuals 50 years old or older who were surveyed between 2003 and 2006. The study primary outcome was overall survival as reported on December 31, 2011. We used design adjusted Cox proportional hazards regression models to estimate the hazard of mortality associated with urinary incontinence. We adjusted the models for demographics and a validated 45-item frailty index incorporating an accumulation of deficits in the domains of health and independence.
Results: Of the individuals 23% reported having urinary incontinence at least a few times per week. Stress urinary incontinence and urge urinary incontinence were associated with a 13.3% (95% CI 7.2-19.7) and 18.4% (95% CI 8.3-29.4) increase in the frailty index, respectively. Without controlling for frailty individuals with urinary incontinence were at higher risk for death (HR 1.39, 95% CI 1.13-1.72). When adjusted for the frailty index, the association between urinary incontinence and mortality was no longer significant (HR 1.10, 95% CI 0.89-1.36).
Conclusions: The association between urinary incontinence and mortality can be understood based on increased frailty in incontinent individuals. Urinary incontinence itself is not independently associated with mortality. In clinical practice these findings underscore the importance of screening for frailty in addition to urinary incontinence.
Keywords: frailty; mortality; nutrition surveys; urinary bladder; urinary incontinence.