Urinary incontinence in women: variation in prevalence estimates and risk factors.

OBJECTIVE: To understand variation in prevalence of urinary incontinence (UI) and risk factors, given different definitions.
METHODS: The National Health and Nutrition Examination Survey 2001-2002 data on UI were used. Prevalence, severity, and associated risk factors of stress, urge, mixed, and any UI were estimated in 2,875 adult women. Severe UI was defined as incontinence a few times or more per week. Moderate UI was defined as an incontinence frequency of a few times per month only, and mild UI was defined as incontinence frequency of a few times per year only. Odds ratios for the association of potential risk factors were examined in a logistic regression model.
RESULTS: The overall prevalence of stress, urge, mixed, and any UI was 23.7%, 9.9%, 14.5%, and 49.2%, respectively. Prevalence of stress UI peaked at the fifth decade. Prevalence of urge and mixed UI increased with age. The largest number of risk factors and the strongest associations were found with severe UI. Age, ethnic background, and weight were significant risk factors common to all UI severity levels. Although parity and hysterectomy were risk factors for moderate and severe UI, they were not for mild UI.
CONCLUSION: Prevalence of UI varies substantially by type and case definition. The stronger associations of known risk factors with severe UI and the lack of risk factors with lesser UI severity types suggest that severe UI includes primarily clinically significant cases, whereas mild UI represents transient or nonpathologic states that may not be clinically significant. LEVEL OF EVIDENCE: III.