Optimized threshold for serum HCV RNA to predict treatment outcomes in hepatitis C patients receiving peginterferon alfa-2a/ribavirin

Summary.  It is unclear whether the current threshold for ‘high’ hepatitis C virus (HCV) RNA level (800 000 IU/mL) is optimal for predicting sustained virological response (SVR). We retrospectively analysed pretreatment HCV RNA levels and SVR rates in 1529 mono-infected and 176 HIV–HCV co-infected patients treated with peginterferon alfa-2a (40 kD) plus ribavirin. We improved the threshold for differentiating low and high viral load by fitting semiparametric generalized additive logistic regression models to the data and constructing receiver operating characteristics curves. Among HCV genotype 1 mono-infected patients, the difference in SVR rates between those with low and high baseline HC…