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.