Concordance between clopidogrel use and prescribing guidelines

BACKGROUND: Clopidogrel is an antiplatelet drug increasingly used in the secondary prevention of atherosclerotic vascular events. Compared with aspirin, clopidogrel has marginal additional efficacy and similar safety, but carries a substantial price premium. It remains unclear whether its use is cost-effective. AIMS: (i) To determine concordance between clopidogrel use and the Pharmaceutical Benefits Scheme and local hospital prescribing guidelines and (ii) to determine the intended duration of clopidogrel therapy and ascertain whether this is supported by other published reports. METHODS: Cross-sectional evaluation by patient interview and chart review of appropriateness of clopidogrel prescribing was carried out for 100 consecutive patients attending a 700 bed metropolitan, primary care and tertiary referral hospital. RESULTS: Clopidogrel was predominantly used for secondary prevention of ischaemic heart disease (60%) and following percutaneous coronary intervention (34%). A significant proportion of patients (29%) received clopidogrel outside the prescribing guidelines. Many patients were intended to receive indefinite therapy for secondary prevention of ischaemic vascular events. Concomitant aspirin therapy was not prescribed in 23% of patients, for 78% of whom it was inappropriate. CONCLUSIONS: There is a lack of concordance between clopidogrel use and prescribing guidelines. In the majority of patients (71%), clopidogrel is used for valid indications but there is considerable leakage of use beyond prescribing guidelines. Concomitant aspirin therapy is often not prescribed in the absence of clinically relevant contraindications. Moreover, treatment is continued in many patients beyond what is supported by current published data.