Genotyping for the IL-28B rs12979860 C>T polymorphism was performed in the genomic DNA extracted
from whole blood, by PCR-based restriction fragment length polymorphism assay. The detailed methodology of the IL-28 B genotyping has been described by our group elsewhere.14 In 136 out of 199 patients (68.3%) a liver biopsy before starting therapy was performed. Grade and stage were scored according to the Ishak system.15 All of the patients were treated with a combination therapy of pegylated (PEG) IFN plus ribavirin. In all, 140 patients (70.4%) received PEG IFN α-2b (PEG-Intron, Schering-Plough) at a dosage of 1.5 μg/kg per week, and 59 patients (29.6%) received PEG IFN α-2a (Pegasys, Roche) at a dosage of 180 μg per week. In patients infected by HCV genotypes 1, 4, and 5, ribavirin (Rebetol, Schering-Plough or Copegus, Roche) was administered according to the body weight (1,000 mg/d
for patients weighing Luminespib mw <75 kg, 1,200 mg/d for those weighing ≥75 kg); in patients infected by HCV genotypes 2 Venetoclax and 3, a flat ribavirin dose of 800 mg/d was used. The duration of antiviral therapy was 48 weeks for genotypes 1, 4, and 5 and 24 weeks for genotypes 2 and 3 infected patients, respectively. The definition of rapid viral response (RVR) was based on undetectable HCV RNA at week 4; complete early viral response (cEVR) was based on HCV RNA undetectable at week 12; end of treatment viral response (EOT) was based on HCV RNA undetectable at the end of antiviral therapy; SVR was based on HCV RNA undetectable 6 months after completing the scheduled period of therapy. Relapsers were defined as patients with HCV RNA reappearance after having reached EOT. Nonresponders were considered patients in whom HCV RNA dropped less than 2 log from baseline at MycoClean Mycoplasma Removal Kit week 12 (null responders) or those in whom HCV RNA dropped more than 2 log from baseline at week 12 (partial responders) but was still detectable at week 24.16 A stopping rule was applied in nonresponder patients. Statistical analysis of the data was performed using the BMDP dynamic statistical software package 7.0 (Statistical Solutions, Cork, Ireland). Continuous variables
are presented as median (interquartile range) and categorical variables as frequencies (%). The associations between categorical variables were evaluated using the Pearson chi-squared test and, when appropriate, the chi-squared test for linear trend. Differences for continuous variables between patients and controls were evaluated using the Mann-Whitney test. The correlation between vitamin A and vitamin D serum levels was assessed by means of Spearman’s rank correlation coefficient. Logistic regression analysis was performed to identify independent predictors of nonresponse to antiviral therapy. The initial model comprised all variables to be tested; those with a nonsignificant coefficient were then removed with a backward approach.