Age modifies the association between waist circumference and stress urinary incontinence in women: A cross-sectional NHANES study.

BACKGROUND

Stress urinary incontinence (SUI) affects nearly half of U.S. women. Central adiposity, measured by waist circumference, may be more pathophysiologically relevant than BMI due to its direct impact on intra-abdominal pressure. However, whether age modifies this association remains unclear.

METHODS

We conducted a cross-sectional analysis of 894 non-pregnant women (55.8 % with SUI) from the 2021-2023 National Health and Nutrition Examination Survey (NHANES). Weighted multivariable logistic regression examined associations between SUI and waist circumference, age, parity, race/ethnicity, and chronic obstructive pulmonary disease (COPD). An age × waist circumference interaction term was tested, followed by age-stratified analyses using 41 years as the cutoff.

RESULTS

Parity ((odds ratio (OR) = 1.17, 95 % CI: 1.01-1.36; p = 0.027), race (non-Hispanic White vs. other: OR = 1.13, p = 0.030; non-Hispanic Black vs. other: OR = 0.78, p = 0.001), and COPD (OR = 1.28, p = 0.007) were independently associated with SUI. The age-waist circumference interaction was significant (p = 0.020). In women < 41 years (n = 365), only parity and race predicted SUI. In women ≥ 41 years (n = 529), each 1-cm increase in waist circumference increased SUI odds by 0.3 % (OR = 1.003, 95 % CI: 1.001-1.006; p = 0.013), equivalent to a 1.5 % increase per 5-cm increment, independent of COPD and race.

CONCLUSIONS

Age fundamentally modifies the SUI-adiposity relationship, rendering central obesity a key modifiable risk factor exclusively in women ≥ 41 years while parity dominates in younger women. These findings advocate for age-specific prevention strategies prioritizing waist circumference reduction in older women and pelvic floor rehabilitation post-childbirth in younger women.