Costs and effects of long-term oral anticoagulant treatment after myocardial infarction.

OBJECTIVE: To investigate the costs and effects of long-term oral anticoagulant treatment after myocardial infarction. DESIGN: Cost-effectiveness analysis, based on a randomized, double-blind, placebo-controlled trial. SETTING: Sixty Dutch hospitals. PATIENTS: A total of 3404 hospital survivors of acute myocardial infarction randomized within a median period of 4 days after discharge to either oral anticoagulant treatment or placebo. The mean follow-up was 37 months. INTERVENTION: Oral anticoagulant treatment aimed at a target international normalized ratio of 2.8 to 4.8. MAIN OUTCOME MEASUREMENTS: Costs of hospital stay during readmissions, costs related to major cardiologic interventions, and costs of oral anticoagulant treatment. RESULTS: The costs of oral anticoagulant treatment were estimated at 394 Dutch guilders (Dfl) per patient-year (Dfl 1 = US $0.58). Placebo patients stayed 18,830 days in the hospital compared with 15,083 days for anticoagulation patients. Average costs per patient of medical care during follow-up were estimated at Dfl 10,784 for placebo patients and Dfl 9878 for anticoagulation patients. CONCLUSIONS: Costs of long-term anticoagulant treatment are outweighed by the costs of prevented clinical events.

Assessment of therapeutic quality control in a long-term anticoagulant trial in post-myocardial infarction patients.

Various methods have been described to evaluate efficacy of anticoagulant therapy using the international normalized ratio (INR). We compared the following approaches: (1) total INR's or the most recent measurement; (2) percent time within therapeutic range, with INR changing directly or halfway between visits; and (3) total observation time assuming INR changing linearly. The study population comprised 1700 post myocardial infarction patients. Treatment comprised 3725 patient-years. There were 61,471 INR assessments with target therapeutic level of 2.8-4.8. Acenocoumarol as well as phenprocoumon were employed. Therapeutic achievement in the first months of treatment was low: less than 60% of INR's were in range. Treatment stabilized after 6 months. Patients on acenocoumarol were within range 70% of the time compared to 80% for phenprocoumon. Method 3 is preferred because it incorporates time and is capable of calculating incidence rates at different INR levels. Our findings call for an urgent improvement of standard of anticoagulant control in the first months following commencement of treatment.