Pulmonary arterial hypertension in patients treated with interferon

Isolated cases of pulmonary arterial hypertension (PAH) in patients treated with interferon (IFN) α or β have been reported in the literature. The aim of this study was to describe all consecutive cases of PAH patients with a history of IFN exposure identified in the French reference centre for severe pulmonary hypertension between 1998 and 2012. A total of 53 patients with PAH and a history of IFN therapy were identified. 48 patients had been treated with IFNα for chronic hepatitis C. Most of them had portal hypertension (85%) and 56% had HIV co-infection. Five additional patients had been treated with IFNβ for multiple sclerosis. The diagnosis of PAH was made within 3 years after IFN therapy in 66% of patients. Repeated haemodynamic assessment was available in 13 out of 16 patients exposed to IFN after the diagnosis of PAH. Increased pulmonary vascular resistance >20% was observed in 11 out of 13 cases (median 43% increase; IQR 32-67%). In five of these patients, IFN withdrawal resulted in spontaneous haemodynamic improvement. This retrospective analysis suggests that IFN therapy may trigger PAH. However, most of these patients had other risk factors for PAH. A prospective case-control study is necessary to definitively establish a link between IFN exposure and PAH.