To update estimates of urinary incontinence (UI) prevalence and associated risk factors for community-dwelling adult women in the United States (US) incorporating the most recent data available from the National Health and Nutrition Examination Survey (NHANES)

NHANES is a nationally representative annual household survey that assesses health status through interview questionnaires, physical examinations and laboratory tests. We utilized de-identified publicly available 2015-2018 NHANES weighted data for women 20 years or older to estimate UI prevalence. We limited our analysis to women who had completed the mobile examination, including the computer assisted personal interview portion of the exam (administered by trained interviewers) that included the standardized UI questions. UI type was classified according to reported symptoms in the last 12 months as stress incontinence (leakage with activity), urge incontinence (leakage with urgency), mixed incontinence (leakage with both activity and urgency), or unspecified (leakage without activity or urgency). The Sandvik Incontinence Severity Index (1) quantified condition severity. 

Socio-demographic and medical history components examined included age in years; race/ethnicity (self-reported into broadly defined categories and separated in this analysis as Non-Hispanic Black, Non-Hispanic White, Latinx, Other); BMI (kg/m2); highest education level (less than high school, high school, some college, college graduate or more); smoking history (never, former, current), prior hysterectomy (yes or no); birth history (no births, any vaginal birth, cesarean only); and currently pregnant (yes or no). Depression was assessed by the Patient Health Questionnaire (PHQ-9) and scored as none/mild, moderate, or severe. Anxiety was assessed by the General Anxiety Disorder-7 (GAD-7) and scored as none/mild, moderate, or severe. Physical activity level was assessed by the Global Physical Activity Questionnaire and scored as none, moderate, or active. Functional limitations were assessed in domains of activities of daily living (4 items), instrumental activities of daily living (3 items), leisure and social activities (3 items), lower extremity mobility (2 items) and general physical activity (8 items). Respondents who answered they had any difficulty on any item in a domain were coded as having dependence in that domain. Respondents were then classified into independent in all domains, dependent in 1-2 domains, and dependent in 3-5 domains. Diabetes mellitus was classified as yes or no, with the “no” category including those who only had gestational diabetes.

Demographics and medical co-morbidities were categorized and evaluated for statistically significant associations with UI using the chi-square test. Multivariable logistic regression modeling determined adjusted associations with UI.

There were 19,225 respondents in the 2015-2018 surveys combined, of which 9,449 were males, leaving 9,776 females. An additional 3,937 people under age 20 years were removed, leaving 5,839 participants. Of those, 833 people did not complete the mobile examination center computer assisted personal interview, leaving 5,006 participants in the main analytic sample. 

Of these 5,006 women with complete data, 3,018 (61.8%) had any UI; 32.4% reported UI at least monthly and 9.8% reported daily UI. Of those with any UI, 37.5% had stress, 22.0% urge, 31.3% mixed, and 9.2% unspecified incontinence. While 32.5% of women with UI were ‘not at all’ bothered, level of bother was ‘a little’ for 33.8% and ‘somewhat’ or greater for 33.7%. Sandvik incontinence severity index correlated with moderate or severe incontinence for 46%. UI prevalence ranged from 36.8 to 83.2 percent and was most prevalent in women 70 years and older. Notably, all races and ethnicities reported a UI prevalence of greater than 50%. 

The prevalence of UI increased with increasing age, BMI, functional dependence, and severity of anxiety and depression (Table 1) and these associations were confirmed in the multivariable model (Table 2). Women who identified as non-Hispanic Black or Latinx were less likely than non-Hispanic White women to report UI. Prior vaginal birth and some college education were also associated with higher odds of UI. In the multivariable model, UI was not associated with diabetes, prior hysterectomy, smoking, physical activity level, or current pregnancy.

In a nationally representative US population health survey, the prevalence of UI among community dwelling adult women was 62%, and 32% of adult women experienced UI at least monthly. Pure stress incontinence was most common, followed by mixed incontinence, urge incontinence, and unspecified incontinence. Age >70 years and BMI >40 kg/m2 had the strongest association with UI in multivariable modeling.

More than 60% of community dwelling adult US women experience UI, a large increase from prior estimates (38-49%) using NHANES data from 1999-2004. This increase may be related to our aging population and increasing obesity prevalence.

H Sandvik H, Hunskaar S, Seim A, Hermstad R, Vanvik A, Bratt H. Validation of a severity index in female urinary incontinence and its implementation in an epidemiological survey. J Epidemiol Community Health 1993 Dec;47(6):497-9. DOI: 10.1136/jech.47.6.497