To the Editor Qamar et al1 examined the interindividual variation in response to evolocumab and documented that at 4 weeks of treatment, 80.2% and 92.9% of patients treated with evolocumab had low-density lipoprotein cholesterol (LDL-C) level reductions of 50% or greater and 30% or greater, respectively. The Discussion section provides a complete set of the reasons for interindividual variation in the LDL-C response. The Discussion section does not mention intraindividual differences in the response, depending on how long after the injection the LDL-C level was measured. In 2017,2 my coauthor and I reported a patient treated with alirocumab, the other available proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitor, whose LDL-C level varied 143%, from 37 mg/dL (to convert to millimoles per liter, multiply by 0.0259) when measured 1 day after drug administration to 90 mg/dL when measured 13 days after drug administration. This is only a case report, but the authors and clinicians should consider the possibility that the LDL-C reduction from PCSK9 inhibitors may vary depending on the time after the last injection. This could have clinical implications because, as noted by Qamar et al,1 some insurers evaluate the magnitude of the LDL-C reduction to allow continued use of these drugs.
Thompson PD. Interindividual and Intraindividual Responses to PCSK9 Inhibition. JAMA Cardiol. 2019;4(6):600. doi:10.1001/jamacardio.2019.1194
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