Oral contraceptives and relative risk of death from venous and pulmonary thromboembolism in the United States.

Abstract

This calculation of relative risks of deat from tromboembolism for women using oral contraceptives was based on the International Classification of Diseases (ICD) Seventh Revision categories 460-468 obtained from the U. S. National Center for Health Statistics. Mortality rates for women and men white and non-white less than 45 years were grouped from 1956-1961 and 1962-1966. It was assumed that oral contraceptive use was increasing linearly in each age group that risk of death for non-users was a linear function of time and that observed mortality in a given year would be a mixed rate for users and non-users. The use rates were estimated from the percent of married women and the percent using the pill (published data). Slopes of increasing mortality were calculated for each group by age sex for the years before and after 1961. Relative risks computed from these slopes clustered in the range from 3 to 9 with higher rates for white women aged 40 to 44 and non-white women aged 35-39. These relative risks coincided with British estimates both case-control studies and trend analysis.