BACKGROUND: Estrogen is known to affect the urethral mucosa and smooth muscle and has been part of the medical management of urinary incontinence in postmenopausal women. The clinical effectiveness of this therapy is controversial.
POPULATION STUDIED: Study participants included a total of 1525 postmenopausal women younger than 80 years with coronary heart disease who had not had a hysterectomy. All eligible women reported at least weekly urinary incontinence at the beginning of the study period.
STUDY DESIGN AND VALIDITY: The original Heart and Estrogen/progestin Replacement Study (HERS) enrolled 2763 postmenopausal women with established coronary heart disease to evaluate the role of hormone replacement therapy in the prevention of coronary heart disease. Of these women, 1525 participants reported at least weekly urinary incontinence and were included in this analysis. Patients were assigned by computer-generated random numbers to receive daily oral conjugated estrogen (0.625 mg) and medroxyprogesterone acetate (2.5 mg) in one tablet (Prempro; Wyeth Ayerst Research, Radnor, Pa) or identical placebo (concealed allocation assignment). Both participants and study personnel were blind to treatment status. Participants completed questionnaires concerning voiding habits and incontinence.
OUTCOMES MEASURED: The main outcome studied was the severity of incontinence, defined as the number of incontinent episodes per week. Outcomes were measured with a questionnaire conducted by blinded investigators at 4 months and then annually for 4 years.
RESULTS: Follow-up at 4 years was 98% complete in both the treatment and control groups. Urinary incontinence improved in 21% of the women taking hormones compared with 26% assigned to the placebo group, while 39% of the women in the hormone group reported worse incontinence compared with 27% of women in the placebo group (P=.001; number needed to harm=8). These results represented the mean of all follow-up visits and a significant difference was seen as early as 4 months. The actual number of incontinent episodes per week increased an average of 0.7 in the hormone group and decreased by 0.1 in the placebo group (P #060;.001).
Oral combination hormone replacement therapy (estrogen/progestin) should not be used specifically for the treatment of urinary incontinence in postmenopausal women. This study did not address the use of estrogen alone or treatment with intravaginal estrogen. When considering hormone replacement therapy in postmenopausal women, the benefits gained from the decreased risk of primary heart disease and osteoporosis along with the improved control of menopausal symptoms must be weighed against the small increased risk of worsening incontinence in women who already have urinary incontinence.