Variability of bothersome menopausal symptoms over time--a longitudinal analysis using the Estonian postmenopausal hormone therapy trial (EPHT).

Background: Very little data are available on the natural course or level of disturbance of vasomotor symptoms among middle-aged women. Using readily collected trial data we studied the persistence of vasomotor symptoms among untreated women.

Methods: In a trial comparing combined hormone therapy to placebo or no treatment (control groups), a cohort of women aged 50-59 at recruitment were followed annually by questionnaires. Women in the control groups (n = 486) were grouped by the number of years followed, with the prevalence and severity of symptoms calculated both cross-sectionally and longitudinally.

Results: About two thirds of the women (67%) reported vasomotor symptoms and half (46%) bothersome symptoms at recruitment. In the cross-sectional analysis, their prevalence declined between recruitment and 1-year follow-up (32% bothersome symptoms) and 2-year follow-up (27%). Thereafter it remained about the same level. In the longitudinal analysis, there was a notable variation in the prevalence of disturbing vasomotor symptoms over time, time entering the study and the compliance to the surveys. In the two groups having most follow-up times, the proportion of women with bothersome symptoms first increased and then decreased.

Conclusions: There was a notable variability in the development of disturbing vasomotor symptoms over time in a selected group of women aged 50-59. Population-based follow-up studies of untreated women would be useful to estimate the symptom burden.