Use of oral contraceptives and mortality during 14 years' follow-up of Norwegian women

Abstract

Aims: The aim was to evaluate total and cardiovascular disease (CVD) mortality in relation to use of oral contraceptives (OC) in a cohort of women with a relatively high prevalence of smoking and high serum lipid levels. Methods: In all 29,053 women aged 20—49 years were invited to a health survey in 1985—88. Of the total 82% attended and 20,282 women free of known CVD were included in this analysis. The relative risk (RR) of mortality during 14 years of follow-up was compared between OC users and non-users by means of proportional hazards regression. Results: About 50% of 827 OC users were daily cigarette smokers, and the mean total cholesterol level in the cohort was 5.9 mmol/l. There were 518 deaths, of which 10 occurred among the women taking OC at baseline. Of three deaths from CVD among OC users, two occurred in the first year of follow-up. Among non-smokers using OC three women died during the follow-up; none of the deaths was due to CVD. Women using OC of any type had no different adjusted total mortality (RR 0.87; 95% CI 0.46—1.65) or CVD mortality (RR 1.41; 95% CI 0.44—4.56) compared with non-users. Conclusions: The results were consistent with previous evidence which does not indicate that mortality from all causes or CVD is elevated in women using OC.