New overview adds more evidence for safety of third-generation Pill.(Brief Article)

2002 SEP 19 - (NewsRx.com & NewsRx.net) -- A new overview of studies of the Pill and the risk of heart attack, published August 30, 2002, in Human Reproduction, provides a reassuring picture of the safety of the third-generation Pill.

A joint Canadian-British team aggregated seven recent epidemiological studies that investigated the risk of myocardial infarctions (MIs) in users of second- and third-generation oral contraceptives (OCs). They used the well-established method of Petitti to derive pooled estimates.

They concluded that the recent studies consistently demonstrated the increasing safety of both types of Pill - and the third-generation Pills in particular - as far as heart attack risks are concerned.

"Recent controversies about OCs, in particular third-generation OCs, have dwelt upon blood clots in the veins," explained lead investigator Professor Walter Spitzer of McGill University in Montreal. "Less attention has been paid to the safety record of newer OCs in respect to the arteries, and all except one of the recent studies lacked statistical power as stand-alone projects. So, we aggregated the findings of seven studies involving nearly 6500 women since 1996.

"The data corroborate that all oral contraceptives currently on the market formally studied since 1996 as risk factors for MI are safe when used according to their regulatory labels. The absolute rates of occurrence of MI among users in reports since 1995 are low - unequivocally lower than those reported earlier between 1966 and 1995."

The researchers concluded that a worst interpretation of their overview still favors third-generation OCs in the risk of a heart attack. The worst relative risk (RR) for third-generation OC use was found to be 0.62 in comparison to second-generation OC. [An RR of 1.0 indicates no effect, greater than 1.0 harm, and an RR less than 1.0 indicates benefit.]

The authors showed that the range of relative risks of third-generation OCs versus second-generation OCs extends from 0.43 to 0.62, all statistically significant. They believe that 0.44 is the most rigorous estimate because the synthesis incorporates only the studies least affected by any possible bias or design problems. Four different permutations and combinations of the seven studies were done in order to minimize any effect of bias.