Letters

Doctors and patients must decide together whether anticoagulation is appropriate

EDITORThomson et al suggest that variations in recommendations for anticoagulant treatment of atrial fibrillation could be overcome by having a single body responsible for producing evidence based guidelines.¹ Might giving this responsibility to one body lead to a form of medical tyranny in which only one view of who should be offered anticoagulant treatment is held to be valid? Evidence based medicine does not preclude the role of the patient in choosing or declining a particular treatment.²

The evidence base for anticoagulant treatment of non-rheumatic atrial fibrillation is strongly influenced by just six trials, five of which have been conveniently pooled. All suggest that anticoagulation with warfarin is beneficial. Further analyses of the data have attempted to stratify differing degrees of risk and potential benefits.³ Evidence based guidelines that could convey this information to clinicians would be welcome, but to suggest that this evidence can then determine the level of risk at which anticoagulant treatment should be recommended is misleading.

The decision to start anticoagulant treatment for atrial fibrillation is difficult for both doctors and patients. On the one hand, in addition to assessing the risk of a particular patient having a stroke doctors must also consider the extent to which the patient wishes to avoid one, which will vary with the patient's own health beliefs. Then they must balance this with the knowledge that the treatment may also cause the event it is meant to prevent. To this has to be added the practical difficulties of anticoagulant treatment for the patient. What evidence there is for this suggests that the patient's own preference can show as much variation as clinical stratification according to relative risk, on which guidelines would presumably be based.⁴ The role of guidelines in this situation should not therefore extend beyond making available the best evidence on which the doctor and patient together can decide if anticoagulant treatment is appropriate.