LAUSR

AIMS The diagnostic history in the years leading up to the definitive diagnosis of patients with obstructive hypertrophic cardiomyopathy (HCM) has not been studied. METHODS Patients with a delay in the definitive diagnosis of obstructive HCM from January 2009 to March 2019 were identified in the US IBM MarketScan Commercial and Medicare Supplemental Databases if they had an alternative diagnosis indicating a misdiagnosis during the 24 months before the definitive obstructive HCM diagnosis. Resource use and costs associated with the delay were estimated during the same period. RESULTS Of 3,888 eligible patients with obstructive HCM, 59.5% had a delay in definitive diagnosis. Patients received a mean of 4.0 misdiagnoses before the definitive obstructive HCM diagnosis, most of which were other cardiovascular conditions. Consequently, 15.7% of patients may have received inappropriate treatment. Approximately 78.4% of patients visited a cardiologist (mean 4.7 visits) before the definitive obstructive HCM diagnosis. Additionally, 26.8% and 32.1% of patients had an inpatient and emergency room visit, respectively. Annualized healthcare costs associated with the delay were $4,379 per patient. LIMITATIONS The current study used administrative claims data for a commercially insured population. Therefore, the results may not be generalizable to other populations (e.g. those insured by Medicare or Medicaid and the uninsured). Like other database studies, the current study may have suffered from miscoding or undercoding, which may have caused misclassification of patients. Owing to insufficient data, the study could not evaluate all potential consequences of a delay in definitive diagnosis. CONCLUSIONS Most patients with obstructive HCM had a delay of ≤ 2 years before receiving the definitive diagnosis. The diagnostic journey involved multiple potential misdiagnoses, predominantly cardiovascular, as well as a substantial clinical and economic burden on patients and the healthcare system.