FACTORS RELEVANT TO PREVENTING EMBOLIC STROKE IN PATIENTS WITH NONRHEUMATIC ATRIAL-FIBRILLATION

Whether or not to treat patients with non-rheumatic atrial fibrillation with anticoagulants to prevent embolic stroke is a dilemma for physicians. If randomized trials, currently underway, demonstrate a beneficial effect, the dilemma will not be solved because not all of the relevant factors can be addressed by trials. We used current knowledge about non-rheumatic atrial fibrillation and a method of obtaining patient-derived weights for avoiding stroke from eight medically trained subjects, to determine the overall benefit of anticoagulants and to see what factors were relevant and what effect each might have in deciding whether to use anticoagulant therapy. Using standard assumptions, anticoagulants gave an expected benefit for all subjects. The expected benefit (expressed in terms of lives per 1000 saved due to anticoagulants) varied between 5.4 and 46.7. This benefit remained for all subjects when we did a sensitivity analysis for different rates of stroke prevented by anticoagulants and different rates of intracranial hemorrhage caused by anticoagulants. When we used different baseline rates of stroke and different impacts of major hemorrhagic complications the benefit disappeared for 3 and 4 subjects respectively. We found the factors that were most crucial to the decision will not be included in randomized trials: the weight that an individual would place on avoiding embolic stroke vs the risk of intracranial bleeding from anticoagulant therapy; and the rate of embolic stroke that could be expected for the subject at risk. Factors which will be measured in randomized trials, will change results less substantially: the increased risk of major hemorrhages; the proportion of strokes that could be prevented by treatment; the increase in risk of intracranial hemorrhage. This method of analysis suggests that for most patients anticoagulants are beneficial and that the most important factor in determining this result is the value that subjects put on different outcomes.