Low weight predicts neutropenia and peginterferon alfa-2a dose reductions during treatment for chronic hepatitis C.

Treatment-induced neutropenia frequently complicates the treatment course of patients treated with pegylated interferon alfa and ribavirin for chronic hepatitis C. We investigated the effect of weight on the risk for dose reductions caused by neutropenia in patients treated with a weight-independent dose of peginterferon alfa-2a. We retrospectively analysed single centre data for 172 patients enrolled in a multi-centre, open-label trial of peginterferon alfa-2a and ribavirin for chronic hepatitis C. Low body weight was significantly associated with dose reductions due to neutropenia. Patients weighing less than 62 kg had a 35% risk for significant neutropenia as opposed to a 12% risk for heavier patients (P = 0.001), and this side-effect occurred earlier during treatment. Low weight was an independent risk factor by multivariate analysis (hazard ratio 0.956/kg). The risk for treatment-induced neutropenia was associated with body surface area more than with the body mass index. In conclusion, a low pre-treatment weight strongly predicts the need for peginterferon alfa-2a dose reductions. This apparently reflects overall body size more than body fat content. It is prudent to frequently monitor blood counts for smaller-sized patients, especially during the first weeks of treatment.