Menopause: its epidemiology and potential association with chronic diseases.

While there are weak indications that the decline in estradiol levels with menopause has ramifications for the expression of overt disease in women, the associations are not clearly characterized with the exception of osteoporosis. The lack of well-characterized associations is undoubtedly due to the same limitations previously described: difficulty in defining the menopausal stages and difficulty in doing serum hormone sampling. Added to these limitations are other impediments. Chronic diseases will not be expressed within a few short months of the menopause, so the temporal sequence of hormone change with clinical disease expression is difficult to establish. Furthermore, it is likely that menopause is an "enabling" state that allows for the subsequent disease in women with other risk factors. Until sufficient data are available to explore the menopause as both an effect modifier and confounder, inconclusive results are likely to be reported. Future studies of the association between chronic diseases and the menopause need to consider issues similar to those that have arisen relative to studies in symptomatology. There needs to be a more concise definition of menopausal status. Potential confounders, including race/ethnicity, body size, and socioeconomic status, must be considered in both design and analysis. Studies need to be designed to separate the effects of age from those of menopause. Finally, women with medically induced menopause should be evaluated separately from those with natural menopause.