A prospective study of the natural history of urinary incontinence in women.

BACKGROUND: Symptoms of urinary incontinence are commonly perceived to vary over time; yet, there is limited quantitative evidence regarding the natural history of urinary incontinence, especially over the long term.

OBJECTIVE: We sought to delineate the course of urinary incontinence symptoms over time, using 2 large cohorts of middle-aged and older women, with data collected over 10 years.

STUDY DESIGN: We studied 9376 women from the Nurses' Health Study, age 56-81 years at baseline, and 7491 women from the Nurses' Health Study II, age 39-56 years, with incident urinary incontinence in 2002 through 2003. Urinary incontinence severity was measured by the Sandvik severity index. We tracked persistence, progression, remission, and improvement of symptoms over 10 years. We also examined risk factors for urinary incontinence progression using logistic regression models.

RESULTS: Among women age 39-56 years, 39% had slight, 45% had moderate, and 17% had severe urinary incontinence at onset. Among women age 56-81 years, 34% had slight, 45% had moderate, and 21% had severe urinary incontinence at onset. Across ages, most women reported persistence or progression of symptoms over follow-up; few (3-11%) reported remission. However, younger women and women with less severe urinary incontinence at onset were more likely to report remission or improvement of symptoms. We found that increasing age was associated with higher odds of progression only among older women (age 75-81 vs 56-60 years; odds ratio, 1.84; 95% confidence interval, 1.51-2.25). Among all women, higher body mass index was strongly associated with progression (younger women: odds ratio, 2.37; 95% confidence interval, 2.00-2.81; body mass index ≥30 vs <25 kg/m2 ; older women: odds ratio, 1.93; 95% confidence interval, 1.62-2.22). Additionally, greater physical activity was associated with lower odds of progression to severe urinary incontinence (younger women: odds ratio, 0.86; 95% confidence interval, 0.71-1.03; highest vs lowest quartile of activity; older women: odds ratio, 0.68; 95% confidence interval, 0.59-0.80).

CONCLUSION: Most women with incident urinary incontinence continued to experience symptoms over 10 years; few had complete remission. Identification of risk factors for urinary incontinence progression, such as body mass index and physical activity, could be important for reducing symptoms over time.