Heart attack survivors who take medications regularly have better mortality rates

A new study from the Institute for Evaluative Sciences (ICES) shows that heart attack survivors who are prescribed statins or beta-blockers have lower mortality rates if they are compliant with taking their drugs.

“While previous studies have demonstrated a positive association between drug adherence and survival, no study has investigated whether this improved survival is because of the drugs themselves, or because of healthier lifestyles which often accompany compliant behaviours,” said Dr. David Alter, ICES Scientist and senior author of the study.

To further explore the relationship between drug adherence and mortality, ICES investigators tracked 31,455 Ontario heart attack survivors 66 years of age and older who were prescribed statins, beta-blockers, or calcium-channel blockers between April 1, 1999 and May 1, 2003. Within this group, patient adherence (an indirect, long-term measure of pill compliance) was subdivided into three categories: high (80% or greater), intermediate (79 to 40%), or low (less than 40%).

The results showed that the risk of mortality was as much as 25% higher among patients whose adherence was poor, compared to the risk for their high adherence counterparts. The association between adherence and mortality was strongest for statins, followed by beta- blockers. There was no relationship between adherence to calcium-channel blockers (a drug which has no proven survival benefits when administered after heart attacks) and mortality.

“Our results show that the association between improved drug adherence and lower mortality rates is only present in patients who take evidence-based medications with proven survival advantages,” said Dr. Alter. “As such, the reason for improved survival appears to be mediated by drug effects more so than behavioural attributes. This underscores the need to encourage improved drug compliance among patients in order to maximize the survival gains of these drugs.”

The study, “Relationship between adherence to evidence-based pharmacotherapy and long-term mortality after acute myocardial infarction”, is in the January 10, 2007 issue of the Journal of the American Medical Association (JAMA).

Author affiliations: ICES (all authors); Clinical Epidemiology Unit, Sunnybrook Health Sciences Centre (Dr. Alter); Division of Cardiology and the Li Ka Shing Knowledge Institute, St. Michael’s Hospital (Dr. Alter); Department of Medicine, and Department of Health Policy, Management and Evaluation, University of Toronto (Dr. Alter); National Institute of Public Health, Oster Farimagsgade 5, DK-1399, Copenhagen K, Denmark (Dr. Rasmussen).

ICES is an independent, non-profit organization that uses population-based health information to produce knowledge on a broad range of healthcare issues. Our unbiased evidence provides measures of health system performance, a clearer understanding of the shifting healthcare needs of Ontarians, and a stimulus for discussion of practical solutions to optimize scarce resources. ICES knowledge is highly regarded in Canada and abroad, and is widely used by government, hospitals, planners, and practitioners to make decisions about care delivery and to develop policy.

FOR FURTHER INFORMATION, PLEASE CONTACT:

• Julie Dowdie
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