Rationale and design of the self-management of anticoagulation in patientswith non-valvular atrial fibrillation (SMAAF) study

The objective of this open, randomized, multicenter study is to investigate the benefits and economic efficiency of self-management of oral anticoagul ation in patients with atrial fibrillation (SMAAF study) in comparison with a group of patients given conventional care by a general practi tioner or specialist. Two thousand patients suitable for self-management will be assi gned at random to either the self-management group or the control group. Th e numbers of thromboembolic and hemorrhagic complications requiring treatme nt during the 2-year follow-up period will be recorded as the primary end p oint. The secondary endpoint variables will be maintenance of the INR value in the individual target range, INR variance, the course of complications over time, and the cost efficiency of self-management compared with the rou tine procedures. The last of these parameters will include the diagnostic a nd/or therapeutic measures carried out, the duration of inpatient hospital treatment, and the social consequences (subsequent rehabilitation treatment , inability to work, forced rentirement). The estimate of the required numb er of patients was based on the assumption that during longterm anticoagula nt therapy within the framework of primary and secondary prevention 4 % of patients with chronic non-valvular atrial fibrillation would have severe th romboembolic of hemorrhagic complications each year. Since this rate can be halved by selfmanagement, a one-tailed chi(2)-test of 80 % power and a 5 % significance threshold would require n = 997 patients per group. The resul ts of the SMAAF study will establish the socioeconomic benefits of selfmana gement in patients with non-valvular atrial fibrillation.