Grappling with the risks and benefits of hormone replacement therapy (HRT) is nothing new for postmenopausal women. Researchers have now added more fuel to the fire, with evidence that HRT could play a role in incontinence.
"Our main finding, which comes in particular from one huge trial, is that one type of HRT — systemic conjugated equine estrogen (CEE) — may make urinary incontinence worse," said June Cody, a methodologist at the Cochrane Incontinence Review Group at the University of Aberdeen in Scotland.
"In addition, in this large trial, women who did not have incontinence at first were more likely to develop incontinence than those who took a placebo."
In an updated systematic review in the upcoming issue of The Cochrane Library, Cody and colleagues also found that significantly more women who used local (vaginal) estrogen reported that their incontinence symptoms improved when compared to women who used a placebo. This result comes from small studies, however, which might have had limitations.
Millions of women experience incontinence — an involuntary and embarrassing leakage of urine that can lead to social isolation and even stigma. There are several kinds of urinary incontinence, including stress and urge incontinence. Stress incontinence can occur when someone is coughing or sneezing, while urge incontinence occurs when one feels a sudden strong urge to urinate.
"The original (2003) Cochrane review on incontinence grouped women according to different types of incontinence — stress, urge or mixed," Cody said. "In this update, we rearranged things to look separately at local or systemic delivery. We then honed in on the different types of estrogen. When we looked at the research with CEE, it seemed to make all types of incontinence worse."
The review appears in the current issue of The Cochrane Library, a publication of The Cochrane Collaboration, an international organization that evaluates research in all aspects of health care. Systematic reviews draw evidence-based conclusions about medical practice after considering both the content and quality of existing trials on a topic.
This systematic review of 33 randomized trials comprised 19,313 incontinent postmenopausal women. In the review as a whole, 9,417 women received estrogen systemically, from oral tablets, skin patches or subcutaneous implants. Another 735 women received estrogen locally by means of a vaginal cream, tablet, vaginal ring or other device. The studies included control groups of women who received a placebo or a different treatment. Half of the trials took place in the United States.
Cody said that the results of two trials, which included 17,642 women, dominated the findings. One study reported on a subset of women from the Women's Health Initiative, which collected incontinence data on 23,296 women — 16,117 of whom were incontinent. The second largest study included 1,525 women with incontinence.
The main purpose of the studies was to look at outcomes such as breast cancer, stroke, heart disease and bone fracture, but they also looked at incontinence. The findings of both studies were the same, whether women were taking estrogen alone, or estrogen and progestogen (for women with an intact uterus): Incontinence worsened for those using HRT with conjugated equine estrogen.
Curiously, smaller studies suggested that systemic estrogen helps incontinence, Cody said. Women in these trials, however, received different types of estrogen, such as estriol or estradiol — but not CEE.