Comparison of a rapid point-of-care and two laboratory-based CYP2C19*2 genotyping assays for personalisation of antiplatelet therapy

Background A quick CYP2C19*2 genotyping assay can be useful in personalised antiplatelet-therapy. Objective To apply a rapid point-of-care (POC) CYP2C19*2 genotyping assay for personalisation of antiplatelet therapy in patients undergoing percutaneous coronary intervention (PCI) and to compare this POC assay to two laboratory-based CYP2C19*2 genotyping assays. Setting Cardiac Catheterisation Suite and Molecular Diagnostics Unit in a general hospital. Methods A buccal sample was collected for POC CYP2C19*2 genotyping with the Spartan (TM) RX system (Spartan Bioscience). A whole blood sample was collected from the same patients for laboratory-based CYP2C19*2 genotyping with a TaqMan(A (R)) allelic discrimination assay (Life Technologies) using real-time quantitative PCR and with the GenID(A (R)) reverse dot-blot hybridisation assay (Autoimmun Diagnostika GmbH). Each patient was genotyped as a non-carrier of CYP2C19*2 (*1/*1), a carrier of one CYP2C19*2 allele (*1/*2), or a carrier of two CYP2C19*2 alleles (*2/*2). Genotyping, interpretation and communication of genotype results (*1/*2, *2/*2) to the consultant cardiologist was undertaken by a clinical pharmacist researcher. Quantitative and qualitative comparison between the three assays was carried out. Main outcome measures Application of a rapid POC CYP2C19*2 genotyping assay for antiplatelet therapy individualisation; comparison of the POC CYP2C19*2 genotyping assay to two laboratory-based assays. Results The total sample consisted of 34 Caucasian patients. With the POC assay, 21 patients were genotyped as non-carriers of CYP2C19*2, 12 patients as carriers of one CYP2C19*2 allele and one patient as a carrier of two CYP2C19*2 alleles. With both laboratory-based assays, the same 21 patients were genotyped as non-carriers of CYP2C19*2, however 13 patients were genotyped as carriers of one CYP2C19*2 allele and no patients were genotyped as carriers of two CYP2C19*2 alleles. Agreement in genotype results was 97 % (kappa = 0.939) between the POC assay and both laboratory-based assays and 100 % (kappa = 1.000) between the two laboratory-based assays. Conclusion Compared to both laboratory-based genotyping assays, the POC assay is accurate and reliable, provides rapid results, can process single samples, is portable and more operator-friendly, however the tests are more expensive.