Pulmonary arterial hypertension associated with interferon therapy: a population-based study

BACKGROUND: Isolated cases of pulmonary arterial hypertension (PAH) with interferon α or β therapy have been reported, but no population-based estimates of the incidence of the disease after interferon exposure are available. The aim of this study was to determine the incidence of PAH after initiation of interferon therapy, using a large commercial insurance database. METHODS: Using National Drug Codes (NDCs) and Healthcare Common Procedure Coding System (HCPCS) codes, we utilized the Clinformatics™ Data Mart (CDM) database to identify subjects between 20 and 65 years old who received α or β interferon therapy between April 2001 and December 2012. Patients were followed from one year prior to the first medication claim for interferon to the first diagnosis of pulmonary hypertension using ICD-9-CM codes 416.0 and 416.8, or disenrollment. In those subjects diagnosed with pulmonary hypertension, a prescription for PAH-specific medications was used as a surrogate endpoint. RESULTS: We identified 20,113 subjects who received interferon therapy during the study period. The median follow-up was 20 months. Pulmonary hypertension occurred in 71 subjects, and PAH-specific medications were prescribed to 7 of these subjects. CONCLUSION: Although our analysis showed that the development of PAH is a rare event with interferon therapy, the risk of developing the disease is several fold higher than that for the general population.