Adherence to Drugs That Prevent Cardiovascular Disease: Meta-Analysis on 376,162 Patients
What is the estimated adherence to recommended pharmacotherapy for primary and secondary prevention of coronary heart disease?
This was a meta-analysis using data from 20 studies, which addressed adherence for seven classes of drugs including aspirin, angiotensin-converting enzyme inhibitors, angiotensin-receptor blockers, beta-blockers, calcium-channel blockers, thiazides, and statins. Adherence was assessed using prescription refill frequency for each drug class. An initial search of PubMed identified 2,433 citations, from which 80 were reviewed, with 17 meeting inclusion criteria. An additional three articles were included after being identified from research of the citations from relevant studies.
A total of 376,162 patients (mean age 64 years, 49% male) were included from 20 studies. Eleven studies included patients treated for primary prevention, and nine studies included patients treated for secondary prevention. The summary estimate for adherence across all studies was 57% (95% confidence interval [CI], 50-64) after a median of 24 months. There were statistically significant differences in adherence between primary and secondary prevention: 50% (CI, 45-56) and 66% (CI, 56-75), respectively (p = 0.012). Adherence was lower for thiazides (42%) than for angiotensin-receptor blockers (61%) in primary prevention (p = 0.02). 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 per month (p = 0.07), and was unrelated to age or whether patients paid for their pills.
The authors concluded that adherence to prevention treatment is poor and not significantly related to drug class, age, or payment methods, suggesting that comprehensive interventions which improve adherence are needed.
This meta-analysis highlights a significant problem in prevention—the lack of adherence for effective cardiac medications. Further studies to examine factors that are related to long-term adherence are strongly warranted.
Keywords: Angiotensin Receptor Antagonists, Secondary Prevention, Hydroxymethylglutaryl-CoA Reductase Inhibitors, Cardiovascular Diseases, Calcium Channel Blockers, Primary Prevention, Thiazides
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