MedicalResearch.com Interview with:
Thomas J. Povsic, MD, PhD
Duke Clinical Research Institute
Duke University School of Medicine
Durham, North Carolina
MedicalResearch.com: What is the background for this study?
Response: The background for this study is that it is unknown how mandatory reporting of CYP2C19 metabolizer status affects how doctors treat patients or to what degree provision of this information would affect choice of a P2Y12 inhibitor within a clinical trial.
As part of the GEMINI-ACS trial, all patients underwent CYP2C19 metabolizer testing. This trial enrolled patients with a recent acute coronary syndrome and randomized them to aspirin or a low dose of rivaroxaban. All patients were also to be treated with ticagrelor or clopidogrel, which was at the discretion of the investigator. Investigators were given information regarding the CYP2C19 metabolizer status about a week after randomization. Importantly prior to randomization, all investigators were asked how they expected to use this information, and then we followed what they actually did.
MedicalResearch.com: What are the main findings?
Response In short, with enrollment of over 3000 patients, only 1 patient was switched from ticagrelor to clopidogrel based on genetic information. Of 1333 patients initially treated with clopidogrel, investigators were nearly evenly split on whether they would use or not use this information, and ultimately only 23 or only 1.7% were switched based on this genetic information. Even in patients in whom the investigator said that they would switch from clopidogrel if the patient was a reduced metabolizer, they only followed through on this in 13 of 27 cases, or less than half the time.
MedicalResearch.com: What should readers take away from your report?
Response: This study is too small to determine whether using this information is the medically correct approach, but it does suggest that doctors are evenly split on how to use this information, and then often change their minds when the information is provided. This suggests that until there is clear clinical trial data that shows that use of this information is clinically useful, physicians will continue to have equipoise about the utility of this genetic information.
MedicalResearch.com: What should we do in the future?
Response: This research really shows that we need definitive information determining whether or not genetic information can be used to improve patient outcomes. Some might say that this suggests that we should just use more potent P2Y12 inhibitors like ticagrelor in all Acute Coronary Syndrome patients, as these have been demonstrated to improve outcomes in all patient subsets.
I have no disclosures related to this research.
Povsic TJ, Ohman EM, Roe MT, et al. P2Y12 Inhibitor Switching in Response to Routine Notification of CYP2C19 Clopidogrel Metabolizer Status Following Acute Coronary Syndromes. JAMA Cardiol. Published online May 29, 2019. doi:10.1001/jamacardio.2019.1510
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