A new study shows that heart attack survivors who stick with their prescribed medication have a lower risk of dying than those who don't exercise compliance.
"I have seen, in my lifetime, too many friends and people I have known who have not been consistent with medications," Monty Mazin, a heart patient, told 麻豆影视.
"And, quite frankly, they are no longer with us."
Dr. David Alter, Institute for Clinical Evaluative Sciences (ICES) scientist and senior author of the study, said the research looked at the effects of medication apart from a healthy lifestyle.
"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," he said.
While the conclusion seemed straightforward, the researchers faced the daunting task of distinguishing the benefits of drugs from other lifestyle issues.
People who take their medication also tend to stop smoking, improve their diet, exercise -- all lifestyle changes that can improve health.
The findings, released Tuesday, are based on a study of 31,455 Ontario heart attack survivors aged 66 or older. They were prescribed statins, beta-blockers or calcium-channel blockers between April 1, 1999 and May 1, 2003.
The results showed mortality risk was as much as 25 per cent higher among patients whose adherence was poor, compared to the risk for their high-adherence counterparts.
"The more compliant and adherent you are with your medications, the better chance you will have of surviving longer," said Alter.
Drugs with proven survival advantages also suggested a relationship between survival and adherence.
The association between adherence and mortality was strongest for statins, which are cholesterol-lowering drugs, followed by beta-blockers, which inhibit the growth of blood vessels.
There was no relationship between mortality and adherence to calcium-channel blockers -- a drug that has no proven survival benefits when administered after heart attacks, the ICES said in a written statement.
"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 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", was published in the Jan. 10 issue of the Journal of the American Medical Association (JAMA).
Researchers chose to focus on patients of that age group because they represent a vulnerable group with a high baseline cardiovascular risk and "a propensity for premature drug discontinuation due to complexities in medical regiments, tolerance and concerns about harmful adverse effects."
Also, cardiovascular medications are free of charge for patients aged 65 years or older.
"Therefore, affordability factors should not significantly affect adherence propensities," the study says.
The researchers say the study has important clinical and policy implications as it underscores the importance of drug adherence when projecting the survival benefits of evidence-based therapies in the population.
"I would definitely say the medication has saved my life, because I've been taking it regularly for 12 years and I have had no problems whatsoever," said Mazin.
The Institute for Clinical Evaluative Sciences is supported in part by a grant from the Ontario Ministry of Health.
With a report from CTV's Avis Favaro and Elizabeth St. Philip
