By Miriam E Tucker
WebMD Health News
February 24, 2017
Use of menopausal hormone replacement therapy modestly raises the risk for fecal incontinence (FI), new research suggests.
The findings, from nearly 56,000 postmenopausal women in the Nurses' Health Study, were published online February 13 in Gastroenterology by Kyle Staller, MD, a neurogastroenterologist and motility specialist at Massachusetts General Hospital, Boston, and colleagues.
The prevalence of FI ranges from 7% to 15% among community-dwelling women and the risk rises with age, but "the vast majority ... are too embarrassed to tell their doctors about it," Dr Staller told Medscape Medical News.
While the additional FI risk attributed to hormone therapy in the study wasn't huge — 32% greater for current and 26% for former users compared to never-users — it's enough that it could significantly worsen the problem among women who already have mild leakage due to factors such as diabetes, prior multiple vaginal births with anal-sphincter trauma, or neurologic conditions such as multiple sclerosis or Parkinson's, Dr Staller noted.
"These are people who may be on the edge of fecal incontinence and you don't want to give them something that may push them over," he said, but added that on the other hand, "If a woman is relatively healthy other than severe menopausal vasomotor symptoms affecting her quality of life, the benefits of hormone therapy may outweigh the risks."
The finding also supports current recommendations to use hormone-replacement therapy for the shortest duration necessary, he said. "The longer you're on hormone therapy, the higher your risk for fecal incontinence and the longer you're off, the more that risk attenuates. I think this says to clinicians that they need to evaluate each time they see that patient whether she still needs to be on hormone therapy at that time."
First Prospective Study on the Subject
In the prospective Nurses' Health Study, which began in 1976 with 121,701 female registered nurses aged 30 to 55, questions about the type and frequency of fecal incontinence were added to the biennial follow-up questionnaires in 2008, when all the women were postmenopausal.
The population for this analysis was 55,828 women who answered the questions about FI and did not report already having it at that time. Women were considered to have fecal incontinence if they reported incontinence of liquid or solid stool at least monthly.
Study questionnaires also asked the women about type and duration of use of menopausal hormone therapy.
During 2008–2012, 12.2% of the women (6834) reported developing FI. Of those, the consistency was liquid in 48%, solid in 40%, and a combination in 12%.
Incontinence of solid stool represents a much more severe condition, Dr Staller pointed out.
Compared with women who never used hormone therapy, the age-adjusted hazard ratios for incident FI were 1.32 for current and 1.26 for past hormone-therapy users, both statistically significant.
These risk estimates were only mildly attenuated after adjustment for other FI risk factors, including smoking, body mass index, hypertension, diabetes, neurologic disease, cholecystectomy, parity, and for factors associated with hormone exposure, including oral contraceptive use, age at menarche, age at menopause, ovulatory duration, and menopause type.
Compared with current users of estrogen-only hormone formulations, the multivariate hazard ratio for FI was 1.37 for current users of combined estrogen and progestin preparations, also significant.
Although, as noted, the FI risk appeared to increase with longer duration of hormone therapy use, even short-term use was associated with an elevated risk: compared with women who had never used hormone therapy, the adjusted risk for FI was 1.22 for 1 to 5 years of use, 1.24 for 6 to 10 years, and 1.32 for more than 10 years of use (P linear trend ‹ .0001).
However, women who had discontinued hormone therapy more than 2 years prior to the survey did not have an increased risk for FI compared with those who had quit more recently (HR, 1.08).
The link between menopausal hormone therapy and FI was significant for both solid and liquid stool types (HR, 1.27 and 1.30, respectively).
Mechanism Probably Relates to Anorectal Estrogen Receptors
The mechanism between hormone use and fecal incontinence isn't clear, but it is believed to be similar to the better-characterized relationship between hormone-replacement therapy and urinary incontinence.
"The idea is that the tissues are all potentially estrogen-sensitive. Certainly in the case of urinary incontinence we know the tissues around the urethra and vagina are estrogen-sensitive, which is why many complaints about vaginal dryness come up when estrogen is depleted naturally," Dr Staller noted.
And animal data suggest that estrogen receptors are present in the anus and rectum as well.
But if the risk for FI increases with age — and thereby with loss of estrogen in women — why wouldn't replacing estrogen improve it?
"Physiology is always more complex than we understand — merely replacing a hormone doesn't tell the whole story. It's probably a complex regulatory cascade. ...Maybe a little is okay, but a lot is too much," Dr Staller speculated.
One theory, he said, is that "estrogen may be affecting the breakdown of connective tissue that holds everything in the right spot. ...Perhaps having too much estrogen around could release enzymes that break down connective tissue."
Indeed, he pointed out that the same pattern is seen with urinary incontinence: it worsens with menopause, but also with hormone therapy. "If you have too much exogenous estrogen around, it may cause downregulation of tissue."
Starting the Conversation
Dr Staller noted that it is important for physicians to let patients know it's okay to talk about fecal incontinence.
"Even just having this conversation at the time of menopause, when most women won't already have developed fecal incontinence, it's an important opportunity to tell women that this is something that may happen with aging. It sets the tone that says it's okay to talk about it. I think that's a secondary benefit of these data ... it lets patients know doctors are aware of it and it can be treated, in many cases very effectively."
The bottom line, he said, is that "replacing estrogen alone is not the fountain of youth. We've known that for heart disease, for urinary incontinence, and now we know that for fecal incontinence as well... There may be a misperception among patients that taking hormone therapy is going to rejuvenate their pelvic floor. I think clinicians should say that's not the case."
Dr Staller has received clinical trial support from AstraZeneca. Disclosures for the coauthors are listed in the abstract.