The changing scene - an unnecessary pill crisis

A number of case-control studies published in 1995/1996 have shown an appar ent increase in the risk of venous thromboembolism (VTE) associated with th e use of third-generation oral contraceptives (OC). However it was discusse d very early on that these studies were subject to a number of biases or re sidual confounding that would have increased the risk estimates for third-g eneration OC while lowering those for second-generation preparations. Six n ew studies or analyses mere performed trying to take into account many of t he methodological problems that were discussed for the initial studies: Two population-based database analyses in the UK and Germany, a new analysis o f the General Practice Registry database (GPRD) in the UK,an analysis of a new database of the Transnational study,a re-analysis of the original Trans national study with a new technique, and a population-based study in Denmar k. These studies could not confirm a higher VTE risk in users of third-gene ration OC compared with those using second-generation OC. Data on the risk of arterial thromboembolism (ischaemic stroke and myocardial infarction) sh ow no such difference between generations of OC, with a statistically signi ficant reduction in the risk of acute myocardial infarction from first- to third-generation preparations in one major study. Some of the investigators concluded that there is very Likely no increased risk of arterial thromboe mbolism associated with the use of low-dose oestrogen OC in young women who are properly screened for cardiovascular risk factors or for such conditio ns. These findings should be taken into account when interpreting the resul ts of studies on the risk of VTE in women taking combined OC.