Menopausal hormone therapy (MHT), consisting of oral estrogen plus progestin or estrogen alone, considered in the past as treatment for urinary incontinenc, was until recently, credited with many benefits well beyond the indications for symptomatic relief of hot flashes, night sweats, and vaginal dryness. One of the benefits of MHT was to improve the symptoms of urinary incontinence (UI), and it has often been prescribed to treat UI.
Susan L. Hendrix, D.O., of the Wayne State University School of Medicine and Hutzel Women's Hospital, Detroit, and colleagues conducted a study to determine the effects of MHT on the 1-year incidence and severity of symptoms of stress incontinence that occurs when involuntary pressure is put on the bladder by coughing, laughing, sneezing, lifting or straining; urge incontinence that is generally attributable to involuntary contracts of the bladder muscle, and mixed UI ,involuntary leakage associated with urgency and also with exertion, effort, sneezing, or coughing in healthy postmenopausal women. Data analyzed from the Women's Health Initiative [WHI] multicenter double-blind, placebo-controlled, randomized clinical trials of menopausal hormone therapy in 27,347 postmenopausal women aged 50 to 79 years enrolled between 1993 and 1998. Existence of any UI symptoms was known for 23,296 participants at baseline and 1 year. Women were randomized to receive estrogen alone (conjugated equine estrogen, [CEE]), estrogen plus progestin (CEE plus medroxyprogesterone acetate [MPA]), or placebo.
The trials, designed to evaluate the effects of MHT using estrogen and progestin or estrogen alone in preventing coronary heart disease and hip fractures in postmenopausal women, ended prematurely because more harm than benefit was observed.
The researchers found that menopausal hormone therapy increased the incidence of all types of UI at 1 year among women who were continent at baseline. The risk was highest for stress UI (1.87-fold increased risk with CEE + MPA; CEE alone, 2.15-fold increased risk), followed by mixed UI (1.49-fold increased risk with CEE + MPA; CEE alone, 1.79-fold increased risk). The combination of CEE + MPA had no significant effect on developing urge UI, but CEE alone increased the risk by 1.32 fold. Among women who reported having UI at baseline, both frequency and amount of UI worsened in both trials. Women receiving menopausal hormone therapy were more likely to report that UI limited their daily activities and bothered or disturbed them at 1 year.
"In conclusion, the results from this large trial, conducted in multiple centers with an ethnically diverse group of healthy postmenopausal women, indicate that MHT use does not confer protection against any type of UI. On the contrary, both CEE alone and CEE + MPA increased risk of new onset UI among continent women and worsened the characteristics of UI among symptomatic women. Considerations regarding the use of hormone therapy by postmenopausal women for any duration should incorporate the current findings into the established risks and benefits of these agents," the authors conclude.