J. Irvine et al., Poor adherence to placebo or amiodarone therapy predicts mortality: Results from the CAMIAT study, PSYCHOS MED, 61(4), 1999, pp. 566-575
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.