Barriers to clopidogrel adherence following placement of drug-eluting stents.

Background: Nonadherence to clopidogrel after drug-eluting stent (DES) placement is associated with in-stent thrombosis and adverse cardiac events.

Objective: To identify the incidence of and barriers associated with nonadherence to clopidogrel in patients receiving DES.

Methods: Patients who received a DES between March 1, 2004, and August 31, 2005, from a single academic medical center were eligible. Telephone interviews were conducted 6 or more months following discharge. Nonadherence was defined as premature discontinuation of or less than 80% adherence to clopidogrel. Patients were asked to identify barriers to adherence. Differences between adherent and nonadherent patients were analyzed using chi(2) and t-test analysis.

Results: Of the 674 patients identified, 257 (38%) participated. The nonadherence rate was 20%. The majority (58%) of nonadherent patients discontinued therapy prematurely. Patients identified the main reason for discontinuation as medical barriers (18.56%), including perceived adverse effects (9.28%). The incidence of rash was higher in patients who were nonadherent (12% vs 4%; p = 0.049). Overall, 49% of patients recalled receiving discharge counseling regarding adverse effects. A financial barrier was identified by 22 (42%) patients in the nonadherent and 73 (36%) in the adherent group, of whom 64% and 52%, respectively, reported having insurance coverage for medications. Adherent patients reported higher copays ($29.69 vs $18.14; p = 0.01).

Conclusions: Prospective studies should be conducted to aid in identifying patients at risk for nonadherence and possible in-stent thrombosis in order to identify interventions to improve adherence.