Implementing CYP2C19-guided clopidogrel therapy: a scoping review of pharmacogenomic testing services

Abstract

Pharmacogenomic testing for CYP2C19 helps personalise clopidogrel therapy and reduces the risk of experiencing a secondary myocardial infarction in individuals with impaired CYP2C19 function. Routine testing, however, is uncommon and it is proposed that the key requirements and processes of testing services are poorly understood. This scoping review aimed to explore the literature for CYP2C19 testing services for clopidogrel and identify their commonalities to inform the design and delivery of future services. In total, 37 eligible studies describing services across hospital and community settings were retrieved. Key elements of delivery included a multi-disciplinary approach involving physicians and pharmacists, provision of pre-implementation training and education, and electronic communication of test results. Result integration into clinical decision support systems improved the practical application of pharmacogenomic testing. The identification of the key requirements and processes may be used by institutions looking to design and deliver CYP2C19 testing services to guide clopidogrel therapy.

Fig. 1

PRSIMA flow diagram of study selection.

Fig. 2. Comparison of the workflows described across hospital and community settings, with a summary of the common elements of a CYP2C19 testing service for clopidogrel relevant for both settings.

In community-based services (A), pharmacists received pre-implementation training and education prior to study involvement. Once completed, they would recruit and obtain a sample from consenting patients to be mailed to an external laboratory for analysis. The laboratory would email or fax the results to the pharmacists, who would then analyse and generate a report outlining treatment recommendations for the GP and patients. They would then consult with the patient to explain their PGx results and their implications on treatment, and whether any treatment changes were to occur. In hospital-based services (B), numerous HCPs received training (e.g., clinicians, nurses, pharmacists) prior to study implementation. Patients were enrolled and tested if they had been, or were going to be, prescribed clopidogrel as indicated through an EHR alert. Internal labs analysed the sample and reported on the PGx results to the involved HCPs via email, fax or telephone. The PGx results would then be integrated into the patient's EHR. The clinician or pharmacist would then consult with the patient on their results and their implications on existing and future treatments.