Objective: To determine the effect of the number of different drugs with adherence to medication of at least 70% on recurrent admission for myocardial infarction (MI) in patients with a history of MI.
Design: Nested case–control study in a dynamic cohort.
Setting: PHARMO database that contains pharmacy dispensing records and hospital discharge records of 350 000 Dutch citizens.
Subjects: All patients admitted to hospital for first MI (ICD-9 410) from 1991 to 2000 with at least a 30-day survival after admission. Cases were admitted for recurrent MI and were matched for age, sex, and year of admission with controls who did not have a recurrent MI.
Main outcome measure(s): Odds ratio with 95% CI for admission for recurrent MI. Exposure was the number of preventive drugs (antiplatelet agents, statins and β blockers or ACE inhibitors) used for at least 70% of the time.
Results: 389 cases were matched with 2344 controls. The use of one drug was associated with a 6% odds reduction (95% CI 30% reduction to 28% increase) for admission for recurrent MI. The use of two or three drugs was associated with reductions of 26% and 41% (47% reduction to 3% increase and 6% to 63% reduction, respectively). Addition of one drug caused a 16% reduction (4% to 26%).
Conclusions: Multiple drug treatment decreases admissions for recurrent MI in patients with a history of MI. Every addition of a drug, regardless of drug class, reduces the risk even further. These results support the treatment strategies as applied in daily practice.
- myocardial infarction
- secondary prevention
- combination drug therapy
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Funding: This study was supported by an unrestricted grant from the SIR Institute for Pharmacy Practice and Policy and the Scientific Institute of Dutch Pharmacists (WINAp), The Hague, The Netherlands. The funding source had no involvement with the authors’ work
Competing interest: None.
ME van der Elst substantially contributed to the design, analysis and interpretation of data, drafting the article and final approval of the version to be published. He will act as guarantor for the paper. ML Bouvy, CJ de Blaey and A de Boer substantially contributed to the design and interpretation of data, revising the article critically for important intellectual content and final approval of the version to be published.
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