Long term hormone therapy for perimenopausal and postmenopausal women

Hormone therapy (HT) is widely used for controlling menopausal symptoms. It has also been used for the management and prevention of cardiovascular disease, osteoporosis and dementia in older women but the evidence supporting its use for these indications is largely observational.

To assess the effect of long-term HT on mortality, heart disease, venous thromboembolism, stroke, transient ischaemic attacks, breast cancer, colorectal cancer, ovarian cancer, endometrial cancer, gallbladder disease, cognitive function, dementia, fractures and quality of life.

We searched the following databases up to November 2004: the Cochrane Menstrual Disorders and Subfertility Group Trials Register, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, Biological Abstracts. Relevant non-indexed journals and conference abstracts were also searched.

Randomised double-blind trials of HT (oestrogens with or without progestogens) versus placebo, taken for at least one year by perimenopausal or postmenopausal women.

Fifteen RCTs were included. Trials were assessed for quality and two review authors extracted data independently. They calculated risk ratios for dichotomous outcomes and weighted mean differences for continuous outcomes. Clinical heterogeneity precluded meta-analysis for most outcomes.

All the statistically significant results were derived from the two biggest trials. In relatively healthy women, combined continuous HT significantly increased the risk of venous thromboembolism or coronary event (after one year's use), stroke (after 3 years), breast cancer (after 5 years) and gallbladder disease. Long-term oestrogen-only HT also significantly increased the risk of stroke and gallbladder disease. Overall, the only statistically significant benefits of HT were a decreased incidence of fractures and colon cancer with long-term use. Among relatively healthy women over 65 years taking continuous combined HT, there was a statistically significant increase in the incidence of dementia. Among women with cardiovascular disease, long-term use of combined continuous HT significantly increased the risk of venous thromboembolism. No trials focussed specifically on younger women. However, one trial analysed subgroups of 2839 relatively healthy 50 to 59 year-old women taking combined continuous HT and 1637 taking oestrogen-only HT, versus similar-sized placebo groups. The only significantly increased risk reported was for venous thromboembolism in women taking combined continuous HT; their absolute risk remained very low.

HT is not indicated for the routine management of chronic disease. We need more evidence on the safety of HT for menopausal symptom control, though short-term use appears to be relatively safe for healthy younger women.