PCV48 - A Discrete Event Simulation Model For A Pharmacogenomics Test For Statin-Induced Myopathy In Patients Initiating A Statin In Secondary Cardiovascular Prevention

Abstract

Statin therapy is the mainstay of dyslipidemia treatment and reduces the risk of a cardiovascular event (CVE) up to 35%. Adherence to statin therapy, however, is poor. One reason patients discontinue statin therapy is musculoskeletal pain and the associated risk of rhabdomyolysis. Research is ongoing to develop a pharmacogenomics (PGx) test for statin-induced myopathy as an alternative to the current diagnostic method, which relies on creatine kinase levels. The potential economic value of a PGx test for statin-induced myopathy is unknown. We developed a lifetime discrete-event simulation (DES) model for patients aged 65 years old initiating a statin after a first CVE consisting of either an acute myocardial infarction or a stroke. We estimated the model time-to-event functions using published Kaplan-Meier graphics in cardiovascular (CV) studies. We have assessed the model over the whole spectrum of test sensitivity and specificity. Our model showed that a strategy with a perfect PGx test is cost-effective at all conventional payer willingness-to-pay (WTP) thresholds, with an incremental cost-utility ratio of $4,273 CAD per quality-adjusted life year (QALY). The probabilistic sensitivity analysis shows that when the payer WTP per QALY reaches $12,000, the PGx strategy is favored in 90% of the model simulations. The scenario analyses on the test parameters show that a totally imperfect test (false positive and negative rates of 100%) would still yield a positive net incremental monetary benefit with a payer WTP per QALY of $50,000. We found that a strategy favoring patients staying on statin therapy is cost-effective even if patients maintained on statin are at risk of rhabdomyolysis. Our results are explained by the fact that statins are highly effective in reducing the CV risk in patients at high CV risk, and this benefit largely outweighs the very low risk of rhabdomyolysis.