Further analyses of mortality in oral contraceptive users. Royal College of General Practitioners' Oral Contraception Study.

An analysis has been made of the 249 deaths that have been reported during the course of the Royal College of General Practitioners' prospective study of the health associations of oral contraception. As previously, women who had used the pill were reported to have a 40% higher death rate than women who had never taken oral contraceptives. Virtually all the excess mortality was due to diseases of the circulatory system. Women who had used the pill had a relative risk of 4.3 for deaths attributed to vascular diseases. Most of these were from ischaemic heart disease (relative risk 4.1) and subarachnoid haemorrhage (relative risk 4.0). The larger number of cases now reported has permitted greater discrimination than was possible earlier between subjects with high and low risks. There were few deaths under 35 years of age and the excess annual death rates of 1 per 77 000 women in non-smokers and 1 per 10 000 women in smokers have wide confidence limits, and could have arisen by chance. For women aged 35-44 years the excess annual death rate was 1 per 6700 women in non-smokers and 1 per 2000 women in smokers; at 45 years and above the risks were 1 in 2500 and 1 in 500, respectively. There is now no evidence that the risk is associated with duration of oral contraceptive use. The demonstrated positive association of risk with parity in pill users needs confirmation. Former-users were noted to have an increased risk of death from vascular disease, but it was not possible to determine whether this represents a residual effect of oral contraceptives on the vascular system