I am currently a house officer working at Waitemata DHB. I completed medical school at the University of Auckland, New Zealand, in 2017.
Clopidogrel CYP2C19 Genotype Testing In Stroke Patients
Clopidogrel is used in the acute management of stroke and for secondary prevention. Variations in the metabolism of clopidogrel due to reduced function and increased function alleles in the CYP2C19 gene make the use of this agent of variable effectiveness. The aim of the project is to look at the prevalence of reduced function (*2 and *3) and increased function *17 alleles in patients admitted in stroke ward in North Shore Hospital, Auckland.
CYP2C19 genotype tests are routinely performed for patients admitted to the stroke ward at North Shore Hospital. Data on this was collected over a 6 month period to determine the prevalence of intermediate, poor and ultra-rapid metabolizers.
Overall 66% (77 of 117) patients were normal metabolizers of clopidogrel. 4% (5/117) patients were poor metabolizers and required alternative antiplatelet agents. 28% (33 of 117) were intermediate metabolizers and should be treated with a higher dose of clopidogrel or alternative agents. There were also two ultra-rapid metabolisers. Although the sample size was small, only 17% (1 of 6) Asian and 33% (2 of 6) were normal metabolizers.
Currently there is no mention to test the CYP2C19 genotype in the Australian Clinical Guidelines for Stroke Management 2017. The prevalence of reduced function alleles in the WDHB population is high. Given there is evidence for reduced clinical benefit of clopidogrel in poor metabolizers (Wang et al,2016), CYP2C19 genotyping is useful in the management of patients with stroke to identify those who will benefit from alternative antiplatelet therapy. The test is relatively cheap ($55-70) and should be offered to all patients taking clopidogrel.
Wang Y, Zhao X, Lin J, Li H, Johnston SC, Lin Y et al. (2016) Association Between CYP2C19 Loss-of-Function Allele Status and Efficacy of Clopidogrel for Risk Reduction Among Patients With Minor Stroke or Transient Ischemic Attack. JAMA. 2016 Jul 5;316(1):70-8. doi: 10.1001/jama.2016.8662