In reply
Our trial was limited to men at high risk of a first myocardial infarction.1 The risk in a female population of the same age would be much smaller, and therefore a considerably larger trial would be required to demonstrate a similar relative benefit of warfarin therapy in primary prevention in women. Moreover, it would be expected that the absolute benefit of treatment would be smaller, whereas the risks of treatment would be more or less the same as in men. Details of time taken to achieve the target international normalized ratio and frequency of monitoring are given in the earlier publication from the main trial.2 Men were discouraged from using vitamin supplements. We agree that widespread use of warfarin in the primary prevention of coronary heart disease would have resource implications, but point-of-care coagulometers and computer-assisted dosing, for example, may in the future ease the demands of warfarin administration.