Poor adherence to placebo or amiodarone therapy predicts mortality: Results from the CAMIAT study

Objective: This study examined the relationship between adherence, mortalit y, and psychosocial factors. Methods: Subjects were 1141 patients participa ting in the Canadian Amiodarone Myocardial Infarction Arrhythmia Trial. Poo r adherence to study medication (amiodarone or placebo), measured by pill c ount over 2 years, was defined as the lower 20th percentile of the pill cou nt distribution, Predictors of adherence were also studied and included dem ographic and cardiac variables and, in a subset of participants (N = 671), measures of depression, distress, hostility, and social support. Results: I n survival analysis controlling for cardiac and demographic variables, poor adherence in the placebo and amiodarone groups was associated with an incr eased risk of sudden cardiac death (relative risk (RR) = 2.11, 95% confiden ce interval (CI) = 1.03-4.56, p <.05; and RR = 3.15, 95% CI = 1.34-7.44, p <.01, respectively), total cardiac mortality (RR = 2.04, 95% CI = 1.12-3.72 , p <.02; and RR = 2.49, 95% CI = 1.32-4.72, p <.01, respectively), and all -cause mortality (RR = 2.25, 95% CI = 1.27-3.97, p <.001; and RR = 2.34, 95 % CI = 1.32-4.17, p <.004, respectively). Logistic regression analysis iden tified two predictors of poor adherence to placebo: age > 70 years (odds ra tio = 2.18, 95% CI = 1.11-4.29, p <.03) and social activities in the month before the index heart attack (odds ratio = 1.02, 95% CI = 1.00-1.04, p <.0 5). Conclusions: Poor adherence is associated with a greater risk of mortal ity. The relationship between adherence and social activities suggests a hi gher motivation to adhere to treatment in individuals more engaged in enjoy able activities.