Epidemiological aspects of the menopause

Abstract

During the time in a woman's life when menopause occurs, other changes, unrelated to the cessation of menstruation occur. Despite a large number of epidemiological studies, there is still conflicting information concerning the direct effects of the menopause as opposed to effects of aging per se and related psychosocial changes. The Population Study of Women in Gothenburg undertook 32 years of follow-ups of five birth cohorts around menopause. The aims of this thesis were to study the prevalence and treatment of hot flushes in pre- and post-menopausal women; to assess cardiovascular risk factor profiles in women who would be subsequent users of hormone replacement therapy (HRT), to compare menopausal age in different birth cohorts and to study self reported age at natural menopause.Methods: The Prospective Population Study of Women was initiated in 1968-69, with follow-ups in 1974-75, 1980-81, 1992-93 and 2000-01. At baseline, the participants were 1462 women born in 1908, 1914, 1918, 1922, and 1930, respectively, who were representative of women of the same age in the general population. By using descriptive information provided by subjects over the years, the prevalence of hot flushes at various ages could be studied, as well as the frequency of and changes in the treatment of hot flushes. Using multivariate techniques, comparisons between cardiovascular risk factor profiles in subsequent users and non-users of HRT could be assessed. Secular trends in menopausal age and reproducibility of reported menopausal age were investigated by using multivariate linear regression models.Results: The prevalence of hot flushes increased from 11% in women aged 38, to a maximum of 64% in 54-year-old women, then decreased to 9% in 72-years old. Sedatives and anticholinergics were the most commonly prescribed treatments for hot flushes in 1960s, predominantly replaced by HRT in the 1980s. Hormonal treatment was considered to be effective in around 85% of the women; the corresponding figure was 45% for sedatives/anticholinergic. 179 women (14.9%) used HRT some time during the 24 year follow-up. This group of women belonged to a higher social group and had significantly lower systolic blood pressure compared to the women who would remain untreated. Mean age for natural menopause showed a steady increase of 0.1 years per birth year, for both smokers and non-smokers, independent of selected covariates. Menarche was a significant predictor of menopausal age; women with early menarche underwent menopause somewhat earlier regardless of the cohort effect. The mean difference between first reported and recalled menopausal age was 0.05 years in subjects most recently interviewed at ages 70-78. Women undergoing early menopause (age <45) tended to overestimate and women undergoing late menopause (age >55) tended to underestimate menopausal age.Conclusion: Hot flushes are widespread symptoms in women, peaking around menopause, but present in other age groups. Treatment has changed, from mainly sedatives/anticholinergics in the 1960s, to the more effective HRT medication in the 1980s. Women who would subsequently take HRT had a more favorable cardiovascular risk factor profile before starting HRT medication, suggesting a selection bias. There was evidence of a secular increasing trend in menopausal age in women born 1908, 1914, 1918, 1922 and 1930. Reproducibility of initially reported menopausal age was acceptable at ages 70-78, but women with early and late menopausal age were likely to recall values closer to the mean.