BMJ  2006;333 (4 November), doi:10.1136/bmj.333.7575.0-e

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Poor adherence to drug treatment increases mortality after a heart attack

Research question Does non-adherence to drug treatments affect survival after a heart attack?

Answer Yes. Patients who stop taking their aspirin, blockers, and statins are more likely to die within a year than patients who continue to take at least one of them

Why did the authors do the study? They wanted to find out how many patients stopped taking their prescribed drugs after a heart attack, when they stopped, and whether this affected their survival. They also wanted to explore the factors associated with non-adherence to treatment.

What did they do? They followed up a cohort of 1521 US men and women who had been treated for myocardial infarction and then discharged from hospital taking aspirin, a blocker, and a statin. The authors interviewed all the participants at baseline and then telephoned them at one, six, and 12 months after discharge to find out which drugs they were still taking. The authors also reviewed participants' medical records. Data on deaths came from the social security register of deaths coupled with telephone calls to relatives or the patient's primary care doctor or cardiologist.

The authors derived survival rates at one year for patients who stopped taking all three drugs within a month, and compared them with rates among patients who continued one or more of the treatments. They did further analyses to find out if non-adherence was an independent risk factor for death, and to explore which demographic or treatment characteristics made someone more likely to stop taking treatment.

What did they find? Of the 1521 patients, 184 (12.1%) stopped taking all three drugs within a month of leaving hospital. Another 328 (21.6%) stopped taking one or two, leaving only 1009 (66.3%) taking aspirin, a statin, and a blocker. Those who stopped all three were significantly more likely to die within a year than those who continued taking one or more of their drugs (11.5% v 2.3%, P < 0.001), a difference that was independent of age, sex, treatment in hospital, psychosocial factors, and clinical history (adjusted hazard ratio for death 3.81 (95% CI 1.88 to 7.72)). In multivariable analyses, the only independent factors associated with stopping all three drugs were lack of high school education (odds ratio 1.76 (1.2 to 2.6)) and age. Age was a more powerful risk factor for women (odds ratio 1.77 (1.34 to 2.34) for each 10 year increase) than for men (1.23 (1.02 to 1.47)).

What does it mean? A substantial minority of patients stop taking their prescribed long term treatments after a heart attack, and this adversely affects their chances of survival either directly or indirectly. Most people who were going to had stopped their drugs within a month of leaving hospital. Socioeconomic factors seem more important than clinical factors in identifying those most at risk. These findings suggest that patients go through a vulnerable transition period after leaving hospital, and there may be a need to intensify follow-up to see them through it. The authors say a discussion about sticking with medication should be an essential part of the first outpatient consultation after a heart attack.

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Ho et al. Impact of medication therapy discontinuation on mortality after myocardial infarction. Arch Intern Med 2006;166: 1842-7[Abstract/Free Full Text]

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Primary care can enhance adherence to life saving drugs after a heart attack

Hasnain M Dalal
bmj.com, 11 Nov 2006 [Full text]