HIV–sex interaction effect on risk of hepatitis C–related cirrhosis, decompensation, and hepatocellular carcinoma

Objective: To use a large population-based cohort to quantify whether there is effect modification between sex and HIV status on risk of hepatitis C-associated cirrhosis, decompensated cirrhosis, and hepatocellular carcinoma. Design: A cohort of 65 151 hepatitis C RNA+ individuals from Ontario, Canada was followed from 1999 to 2018 for diagnoses of cirrhosis, decompensated cirrhosis, and hepatocellular carcinoma, using administrative health data. Methods: Time-dependent Cox regression adjusting for patient characteristics was used to quantify the risk of each liver disease outcome in males that are HIV negative (HIV−), females that are HIV positive (HIV+), and males that are HIV+, all relative females that are HIV−. The relative excess risk due to interaction (RERI) was calculated to quantify the magnitude and significance of interaction effects. Results: A significant negative interaction effect between sex and HIV was found for risk of cirrhosis (RERI = −0.52; 95% CI: −0.86, -0.18) and decompensation (RERI = −1.50; 95% CI: −2.32, −0.68), but not for risk of HCC (RERI = 0.44; 95% CI: −0.05, 0.93). Conclusions: The interaction estimates from this population-based cohort indicate that HIV infection increases the risk of hepatitis C-associated cirrhosis and decompensated cirrhosis to a greater extent in females compared to males.