The natural history of urinary incontinence subtypes in the Nurses’ Health Studies

Abstract Background Urinary incontinence (UI) subtypes often differ by symptom severity and treatment profiles; in particular, mixed UI is generally associated with worse symptoms and less successful treatment. Yet, limited information exists on the natural history of different urinary incontinence (UI) subtypes, which could help better identify and treat patients prior to development of more intractable disease. Objective To evaluate the onset of UI subtypes, and transitions between subtypes over 8 years, using two large cohorts of middle-age and older women with incident UI. Study Design We identified 10,349 women with incident UI (stress, urgency, and mixed subtypes), from the Nurses’ Health Study and Nurses’ Health Study II, age 41-83 years, using repeated mailed questionnaires. We defined stress UI as leakage with coughing, sneezing, or activity; urgency UI as urine loss with a sudden feeling of bladder fullness or when a toilet was inaccessible; and mixed UI when women reported that stress and urgency symptoms occurred equally. In subsequent questionnaires 4 and 8 years later, we continued to track symptom severity and subtypes. In addition, to obtain predicted probabilities of UI subtypes 4 years and 8 years after UI onset, we used multivariable-adjusted generalized estimated equations with a multinomial outcome. Results At UI onset in 2004-5, 56% of women reported stress UI symptoms, 23% reported urgency UI symptoms, and 21% reported mixed UI symptoms. Women with stress UI or urgency UI at onset were likely to report the same UI type 4 and 8 years later (Stress UI at onset: 70% and 60% reported stress UI at years 4 and 8, respectively; Urgency UI at onset: 68% and 64% reported urgency UI at years 4 and 8, respectively). Nonetheless, for both stress and urgency UI, women with more severe symptoms at onset were more likely to progress to mixed UI. Women with mixed UI at onset had more variation over time, although the largest subset continued to report mixed UI (45% reported mixed UI at year 4, 43% reported mixed UI at year 8). Few women across all UI subtypes reported resolution of symptoms over 4 to 8 years of follow-up (4-12%). When considering the likelihood of remaining with or progressing to mixed UI over follow-up, according to age, body mass index and UI severity, we found that older and younger women had similar predicted probability of remaining with or progressing to mixed UI (e.g., women Conclusions Most women with incident stress and urgency UI continued to experience similar subtype symptoms over 8 years. However, obese women and those with more severe symptoms were more likely to remain with or progress to mixed UI.