Special intervention reduces CVD mortality for adherent participants in the multiple risk factor intervention trial.
BACKGROUND
Patient adherence affects treatment efficacy, and surprisingly, adherence is frequently associated with reductions in mortality for those receiving placebo.


METHODS
This study considers the role of trial adherence for men (N = 12,338) in the Multiple Risk Factor Intervention Trial (MRFIT), a prospective study of 9-year follow-up mortality following randomization to Special Intervention (SI) or Usual Care (UC). Annual visit attendance rates were used as a measure of adherence.


RESULTS
A significant Adherence x Group Assignment interaction (p =.002) revealed that SI significantly reduced cardiovascular disease (CVD) mortality for highly adherent participants, RR =.91 (95% confidence interval [CI] =.84-.99) but significantly increased CVD mortality for poorly adherent participants, RR = 1.28 (95% CI = 1.05-1.57) when compared to UC. These associations remained after controlling for baseline characteristics (e.g., income), reported illness, or occurrence of a nonfatal CVD event during the trial. The beneficial effect of SI among the adherent participants was partly due to reduced smoking and diastolic blood pressure levels during the trial.


CONCLUSIONS
SI significantly reduced the risk of CVD mortality for participants adherent with the MRFIT, and this effect was accounted for by positive changes in CVD risk factors. These findings suggest a method for evaluating treatment efficacy in subgroups determined by patient responses (e.g., adherence to annual assessment visits) to the treatment program after randomization.
Gump
Brooks B
BB
State University of New York, Oswego, USA.
Matthews
Karen A
KA
D000328:Adult; D000704:Analysis of Variance; D002318:Cardiovascular Diseases / Q000150:complications / Q000401:mortality* / Q000523:psychology*; D002784:Cholesterol / Q000097:blood; D005500:Follow-Up Studies; D006801:Humans; D006973:Hypertension / Q000150:complications; D008297:Male; D008875:Middle Aged; D010349:Patient Compliance / Q000523:psychology* / Q000706:statistics & numerical data; D010353:Patient Education as Topic / Q000639:trends; D015990:Placebo Effect; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects; D017741:Survivors / Q000523:psychology
D002784:Cholesterol