Objectives: to evaluate the association between socioeconomic position (SEP) and adherence to appropriate antiplatelet therapy (AAT) after percutaneous coronary intervention (PCI) in the year following the discharge.
Design: according to scientific guidelines, AAT for PCI patients consists of Clopidogrel for a minimum of 1 month and ideally up to 12 months after discharge, and with Acetylsalicylic Acid (ASA) indefinitely. For each patient, drug claims over a 1-year period after discharge were retrieved from Regional Drug Dispense Registry. Drug use was measured with Proportion of Days Covered (PDC). PDC was computed dividing the total number of dispensed Defined Daily Dose by each patient's follow-up time. Dual antiplatelet therapy with PDC ≥75% and single therapy based on Clopidogrel with PDC ≥75% were considered as AAT. We used a composite area-based index of socioeconomic position by census block of residence built using the 2001 census of Rome, assuming 5 levels (from 1 =High SEP to 5 =Low SEP).
Setting and participants: study population of 5,901 patients resident in Rome, who underwent their first PCI during 2006-2007 were selected from the Hospital Information System.
Main outcome measures: proportions of patients treated with AAT by SEP was measured for the overall year and by semester. The association between SEP and adherence to AAT was estimated through logistic regression models adjusting for factors selected by a stepwise procedure (gender, age, comorbidities, discharged from cardiology or coronary care unit, new user of antiplatelet drugs).
Results: 76% of the study population were men, 96% were aged more than 44 years, and 63% belonged to medium-low SEP. In the 1-year follow-up, the proportion of patients adherent to appropriate antiplatelet therapy was 65%; SEP was associated with AAT (OR high vs. low SEP 1.26; 95%CI 1.05-1.51; p trend =0.002).
Conclusions: during the year after discharge, adherence to AAT of PCI patients was unsatisfactory and it decreased overtime more in medium-low SEP patients than in high SEP patients. Strategies to improve adherence to AAT among patients who underwent PCI need to be identified taking into account the multifactorial nature of poor medication adherence, and in particular patients' socioeconomic position.