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Compliance to heart meds poor reports new study

Robin Wulffson MD's picture
drug compliance, drug adherence, heart medication, heart attack prevention

A number of medications including cholesterol-lowering medicines, blood thinners (i.e., aspirin, Coumadin, and Plavix), and blood pressure-lowering medications can substantially reduce the risk of a heart attack or stroke; however, a new, large study has reported that many patients do not take these medications as prescribed.

Researchers at the Wolfson Institute of Preventive Medicine, Barts and the London School of Medicine, Queen Mary University of London, Charterhouse Square, London published their findings online on June 28 in the American Journal of Medicine.

The researchers noted that the full preventive effect of the aforementioned medications is only realized if treatment continues indefinitely. Therefore, they conducted a meta-analysis to evaluate compliance to heart medications. (A meta-analysis is an analysis of data from a number of similar studies to further validate the findings.) The goal of the study was to provide a summary estimate of adherence to drugs that prevent coronary heart disease, according to drug class and use; the study included individuals who have suffered a myocardial infarction (secondary prevention) and individuals who have not (primary prevention).

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The meta-analysis included data on 376,162 patients from 20 studies assessing adherence using prescription refill frequency for the following seven classes of drugs: aspirin, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, beta-blockers, calcium-channel blockers, thiazides, and statins. The analysis included the impact of age, cost, and treatment duration. Of the 376,162 individuals in the studies, about 275,000 were given a prescription to prevent heart disease while the other 101,000 were already diagnosed with heart disease.

The researchers found that compliance across all studies was 57% after a median of 24 months. They found statistically significant differences in compliance between primary and secondary prevention (primary: 50%; secondary: 66%). Compliance was lower for thiazides (42%) than for angiotensin receptor blockers (61%) in primary prevention. There were no other statistically significant differences between any of the drug classes in primary or secondary prevention studies. Adherence decreased by 0.15% points/month and was unrelated to age or whether patients paid for their pills. The investigators estimated that 130,000 individuals die each year because they do not adhere to their prescriptions.

The authors concluded that adherence to preventive treatment is poor; furthermore, it is not significantly related to the class of drug. They noted that these findings suggested that side effects are not the main cause. They noted that general, rather than class-specific, measures at improving adherence are needed.

Take home message:

This study points to a common problem regarding prescription medications. It is not uncommon for individuals to fail to take medications as prescribed. For example, a patient might be given a 10-day prescription for an antibiotic. Often, after several days, the symptom resolve and th remaining pills languish in the medicine cabinet. Sometimes, the remaining pills are taken without professional advice at a later date. This increases the risk of a relapse and antibiotic resistance. If pills are taken beyond their expiration date, they may lose potency or cause health problems. This study should serve as a reminder of the importance of medication compliance for you or for a loved one on a medication.

Reference: American Journal of Medicine