Pre-existing risk factor profiles in users and non-users of hormone replacement therapy: prospective cohort study in Gothenburg, Sweden

Objective To assess whether risk factor profiles for cardiovascular disease differed, before starting treatment, between women who would subsequently use hormone replacement therapy and those who would remain untreated. Design Prospective population study, initiated in 1968-9, with follow ups i n 1974, 1980, and 1992. Setting Gothenburg, Sweden. Participants 1201 women born in 1918, 1922, and 1930, representative of wom en of the same age in the general population. Main outcome measures Hormone replacement therapy as a function of initial systolic and diastolic blood pressure, waist and hip circumference, waist t o hip ratio, body mass index, serum concentrations of cholesterol and trigl ycerides, smoking status, education, leisure time activity, and socioeconom ic group. Results 179 of the 1201 women (14.9%) used hormone replacement therapy some time during the 24 year follow up period. Multivariate models indicated tha t these women had significantly lower blood pressure, had less obesity, and belonged to a higher social group before the start of treatment than women who would remain untreated. Conclusion Women who would subsequently use hormone replacement therapy wer e already at lower cardiovascular risk before the start of treatment than w omen who would remain untreated. Some of the claimed beneficial effects of treatment may thus be explained by women who would use hormone replacement therapy representing a healthier cohort than women who would remain untreat ed.