The effects of sustained virological response to direct‐acting anti‐viral therapy on the risk of extrahepatic manifestations of hepatitis C infection

Summary Background Direct‐acting anti‐viral (DAA) therapy may have a beneficial role in extrahepatic manifestations of hepatitis C virus (HCV) infection. However, the available data are limited. Aim To examine the effects of DAA treatment on the risk of several extrahepatic manifestations of HCV. Methods We conducted a retrospective cohort study of patients from the US Department of Veterans Affairs Corporate Data Warehouse who had a positive HCV RNA test and received first course of DAAs between 2012 and 2016. We calculated incidence rates by sustained virological response (SVR) status for six extrahepatic manifestations, and effect of SVR on these conditions was evaluated in adjusted Cox regression models. Results Of the 45 260 patients treated with DAA with mean follow‐up of 2.01 years, 41 711 (92.2%) experienced SVR. Incidence rates ranged from 0.17/1000 PY for porphyria cutanea tarda to 21.04/1000 PY for diabetes in the SVR group and 0.51/1000 PY for porphyria cutanea tarda to 23.11/1000 PY for diabetes in the no SVR group. The risk was reduced with SVR for mixed cryoglobulinaemia (adjusted HR (aHR) = 0.23; 95% CI 0.10‐0.56), glomerulonephritis (aHR = 0.61; 95% CI 0.41‐0.90) and lichen planus (aHR = 0.46; 95% CI 0.30‐0.70), but not for non‐Hodgkin's lymphoma (aHR = 0.86; 95% CI 0.52‐1.43) or diabetes (aHR = 0.98; 95% CI 0.81‐1.19). Non significant risk reduction was seen for porphyria cutanea tarda (aHR = 0.33; 95% CI 0.11‐1.03). Conclusions Successful DAA treatment resulting in SVR was associated with significant reductions in the risk of mixed cryoglobulinaemia, glomerulonephritis, lichen planus and possibly porphyria cutanea tarda, but not non‐Hodgkin's lymphoma or diabetes.