Economic Burden of End Organ Damage Among Patients with Sickle Cell Disease in the US

Introduction Sickle cell disease (SCD) is an inherited disorder in which pathology is driven by hemoglobin polymerization and red blood cell sickling, leading to chronic anemia, hemolysis, and episodic vaso-occlusion. Anemia affects the brain, kidneys and cardiovascular system, and is associated with neurocognitive dysfunction, silent cerebral infarction, stroke, renal dysfunction, pulmonary hypertension, and mortality. Limited research has been conducted to quantify the economic burden of end organ damage among patients with sickle cell disease in the US. Methods Patients with ≥3 nondiagnostic SCD ICD-9/ICD-10 codes within 5 years (Jan 1, 2013-Dec 31, 2017) were identified in the MarketScan® Medicaid claims databases. The first date of SCD diagnosis was the index date. At least three months of continuous enrollment with medical and pharmacy benefits prior to the index date, and at least 1 month of continuous enrollment following the index date were required to be included. Each patient's post-index period was divided into a series of 3-month intervals. For each 3-month interval, patients' entire available claims history (as early as 1/1/2008) was checked to identify four types of end organ damage experienced by SCD patients including stroke (within 1st year and >1 year after an acute stroke event), chronic kidney disease (CKD), end-stage renal disease (ESRD), and pulmonary hypertension (PH). Total healthcare costs (plan paid and patient out-of-pocket payment) and healthcare resource utilization (HRU) information were determined for each 3-month interval. Patient characteristics, HRU, and costs were summarized descriptively by type of end organ damage. Three multivariate generalized linear models with loglink function and gamma error distribution (assuming the cost follows an exponential relationship to the weighted average of covariates) were employed to estimate the relative cost ratios of patients with vs. without end organ damage, controlling for patients' demographic and clinical characteristics. Annualized costs for adult patients with each type of end organ damage were estimated based on the regression results. Results A total of 10,784 patients with SCD on Medicaid were identified. Patients were followed for 3.35 years on average, contributing 152,455 intervals (age ≥18: 42.7%; female: 54.6%; urban: 84.4%). Approximately 20% of the intervals had end organ damage. Patients with end organ damage had more days in hospital, ER visits, outpatient visits