Is hormone replacement therapy associated with an increased risk of irritable bowel syndrome?

Hormonal status could be involved in the occurrence of irritable bowel syndrome (IBS). The authors examined the risk of developing IBS in women using hormone replacement therapy (HRT).

Women 50-69 years old with at least one prescription for HRT during 1994-1999 were identified from the General Practice Research Database in the UK (n=40, 119). An aged-matched cohort of 50000 women who never used HRT was sampled from the source population where the HRT cohort was ascertained. Women in the two cohorts were followed to assess the risk of development of IBS. Authors performed a nested case-control analysis to assess the role of duration, route and regimen of HRT use and other risk factors for IBS. The IBS diagnosis was validated by means of a questionnaire sent to the general practitioners (n=660).

The incidence rate of IBS per 1000 person-years was 1.7 in the cohort of never HRT users and 3.8 among HRT users, respectively. Both current and past users of HRT presented an increased risk of IBS compared to non-users, after adjusting for co-morbidity and consultation patterns. This increased risk was observed irrespective of treatment duration, regimen or route of administration of HRT.

The result suggests that HRT use is associated with an increased risk of IBS similar to the one observed among younger premenopausal women with endogenous oestrogenic activity.