1025 Frequency of Diagnosed Acute Intermittent Porphyria in a National Health Care Database

Abstract

INTRODUCTION: Acute hepatic porphyria (AHP) refers to a family of rare, genetic diseases caused by deficient activity of enzymes involved in the heme biosynthesis pathway in the liver, with acute intermittent porphyria (AIP) being the most common subtype. Accumulation of neurotoxic heme intermediates may result in potentially life-threatening acute attacks and chronic symptoms that negatively impact daily functioning and quality of life. Although AIP-related genetic mutations are relatively common (1:1,700), clinical penetrance of the disease is estimated around 1%. European data suggest that the diagnosed prevalence of AHP is approximately 1 per 100,000 individuals. Epidemiologic data specific to AIP are limited. The study aimed to identify AIP patients diagnosed in a nationally representative health care database to estimate prevalence, commonly reported clinical presentations, and health care resource utilization of AIP in the United States. METHODS: This retrospective analysis utilized the IBM® MarketScan® Commercial Claims and Medicare Supplemental Databases. Patients with at least one claim for AIP (ICD-10 diagnosis code E80.21) between October 1, 2015 – June 30, 2018 were selected for analyses. The subset of AIP patients with continuous enrollment for one year preceding and following their first observed AIP diagnosis (index diagnosis) were identified for the measurement of baseline characteristics and outcomes post-index, including healthcare resource utilization (HCRU), medications (including hemin), symptoms, and the frequency of comorbid diagnoses. RESULTS: Approximately 37 million patients within the MarketScan® databases had a medical or pharmacy claim between October 1, 2015 and June 30, 2018; a total of 361 of these patients were identified with a diagnosis of AIP. Among these 361 AIP patients, a partial prevalence estimate of AIP on June 30, 2018 was calculated to be 0.98 per 100,000 (214 AIP patients per 21,807,137 people enrolled on June 30, 2018). Sensitivity analyses around claims-based definitions for identifying AIP revealed 140 patients with ≥2 claims for AIP and 31 AIP patients receiving hemin (Table 1). CONCLUSION: Results from this national representative healthcare claims database demonstrated the frequency of diagnosed AIP in the United States to be similar to estimations previously published in global and European-specific AIP epidemiology studies.