Estrogen has an important role in lower urinary tract function and dysfunction throughout adult life in women. Postmenopausal estrogen deficiency causes atrophic changes in the lower urinary tract and may be associated with urinary frequency, urgency, nocturia, and incontinence. The association of these changes with overactive bladder (OAB) symptoms is unclear. Systemic and vaginal estrogens have been used for many years during and after menopause to manage urinary dysfunction (including symptoms of OAB) despite the lack of adequate controlled trials confirming their efficacy. Data from large epidemiological studies have questioned the benefits of systemic estrogens for menopausal symptoms of incontinence and OAB. In the last decade, concerns regarding breast cancer and thromboembolic disease have been led to a marked reduction in the number of women seeking systemic hormone replacement therapy for menopausal symptoms.
The aim of this article was to review current evidence-based data on the effect of exogenous estrogen therapy on lower urinary tract function in menopausal and postmenopausal women, specifically those with symptoms of OAB. Evidence is reviewed on use of both systemic and vaginal estrogen therapy as well as combination therapy with antimuscarinic agents in this population.
Analysis of the Women’s Health Initiative (WHI) trial data, as well as meta-analyses and systematic reviews, supports the use of vaginal estrogen therapy, but not systemic, for management of OAB. Systemic estrogens (combined estrogen/progestin or estrogen only) as well as oral estrogens did not decrease the risk of overall urinary incontinence (UI); they increased the risk and worsened baseline incontinence symptoms.
Recent published guidelines have established the safety and effectiveness of low-dose vaginal estrogens for treatment of women with urogenital atrophy and lower urinary tract symptoms. There is evidence that the vaginal route may be useful in managing symptoms of OAB, especially symptoms of urgency. The well-known adverse effects of systemic estrogens on the breast and uterus do not occur with vaginal administration.
Combined use of vaginal estrogen and antimuscarinic therapy in postmenopausal women with OAB has been investigated. This combination could potentially increase compliance and persistence though improved efficacy as well as reduced troublesome antimuscarinic adverse effects because of the lower doses used. Three prospective randomized trials investigated the effects of 12 weeks of combined use of vaginal estrogen and antimuscarinic therapy for management of postmenopausal women with OAB. Results of these 3 trials were contradictory. Further studies are needed to investigate combined use of newer, more efficacious antimuscarinics and low-dose vaginal estrogens.
Robinson D, Cardozo L, Milsom I, Pons ME, Kirby M, Koelbl H, Vierhout M. Oestrogens and overactive bladder. Neurourol Urodyn. 2014 Sep;33(7):1086-91. doi: 10.1002/nau.22464. Epub 2013 Jul 19.