Background & Aims: Recent studies have suggested that insulin resistance exerts a strong influence on chronic hepatitis C virus (HCV) infection. We analyzed pretreatment factors useful for predicting sustained virological response (SVR), especially interleukin (IL) 28B polymorphism and Homeostasis Model Assessment of Insulin Resistance (HOMA-IR). Methods: This cohort study consisted of 328 chronic hepatitis C patients with HCV genotype 1 who were treated for 48 weeks with pegylated interferon (PegIFN) α-2b and ribavirin (RBV). Genotyping of the polymorphisms in the IL28B gene region (rs8099917) on chromosome 19 was performed on DNA collected from each patient. Results: No significant difference in IL28B genotype distribution was found according to HOMA-IR. Multivariate analysis identified the IL28B TT genotype (OR = 5.97, 95% CI 2.15-16.55, p = 0.0006) and the baseline HOMA-IR (OR = 0.65, 95% CI 0.48-0.87, p = 0.0044) as significant, independent pretreatment predictors of SVR. Receiver operating characteristic analyses to determine the optimal threshold values of HOMA-IR for predicting SVR showed that the areas under the curve (AUC) were high for both IL28B TT (AUC = 0.774, HOMA-IR cut-off value: 2.45) and IL28B TG/GG genotypes (AUC = 0.772, HOMA-IR cut-off value: 1.55). Conclusions: For HCV genotype 1, both IL28B and baseline HOMA-IR are independent pretreatment predictors of SVR in patients treated with PegIFNα-2b and RBV. Insulin resistance undermines the advantages of IL28B polymorphism to obtain SVR.
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