We welcome the cautious interpretation of the recent trials of warfarin in atrial fibrillation provided by the authors of this article and concur with their concerns about the generalisability of the results of this group of trials. We congratulate them on introducing the concept of packages of care in this context--packages that include not just the prescribing of drugs but rigorous selection of patients and meticulous monitoring and follow up.

The authors' analysis of the trials highlights the huge exclusion rates of patients initially considered eligible and, correctly in our view, links these stringent exclusion criteria and the intensity of follow up of patients to the uniformly low bleeding rates that were found in all the trials. We would go further and point out that for quite large periods of time in all but one of the trials patients were in fact underanticoagulated according to …