DETERMINANTS OF COMPLIANCE WITH ANTICOAGULATION - A CASE-CONTROL STUDY

BACKGROUND: The number of patients for whom long-term anticoagulation is indicated has increased dramatically over the past decade. Good pat ient compliance is necessary to safely realize the benefits of anticoa gulation, yet barriers to compliance with anticoagulation therapy have not been studied. METHODS: We conducted a case-control study in the A nticoagulation Therapy Unit (ATU) at Massachusetts General Hospital. F orty-three patients who had been discharged from the ATU for noncompli ance (cases) and 89 randomly selected compliant ATU controls were inte rviewed. Noncompliant cases had self-discontinued warfarin or were tak ing warfarin with inadequate monitoring of international normalized ra tio (INR) levels. Telephone interviews assessed sociodemographic featu res, indication for anticoagulation, patient satisfaction, and health beliefs. RESULTS: Noncompliant cases were more likely to be younger (m ean 53.7 years versus 68.7 years, P < 0.0001), male (odds ratio [OR] 3 .5, 95% confidence interval [CI] 1.5, 8.2), and nonwhite (OR 6.4, 95% CI 1.9, 21.9), and less likely to have had a stroke or transient ische mic attack (OR 0.2, 95% CI 0.1, 0.7). In open-ended questioning, cases were more likely to report that they did not know why warfarin had be en prescribed (OR 4.4, 95% CI 1.4, 14.2). Noncompliant cases were more likely not to have a regular physician (OR 11.1, 95% CI 3.6, 50.0); a mong patients with a regular physician, noncompliant cases were more l ikely to feel dissatisfied. Examination of health beliefs revealed tha t noncompliant cases felt more burdened by taking warfarin, and percei ved fewer health benefits. CONCLUSIONS: Patients who are noncompliant with warfarin share distinctive clinical characteristics. Notably, you nger, male patients who have not experienced a thromboembolic event ar e more likely to forego INR testing or to stop anticoagulation therapy completely. Improved patient education, physician involvement, and ea se of monitoring may improve compliance, particularly among younger ma le patients. (C) 1997 by Excerpta Medica, Inc.