Thyroid dysfunction in patients with chronic hepatitis C receiving a combined therapy of interferon and ribavirin: Incidence, associated factors and prognosis

Abstract Background and Aims: Interferon (IFN) plus ribavirin therapy for chronic hepatitis C (CHC) virus infection has been associated with thyroid dysfunction. The goal of our current study was to elucidate predictive factors of: (i) thyroid dysfunction associated with combination therapy; and (ii) long‐term reversibility of thyroid dysfunction. Methods: In total, 461 patients with CHC and normal baseline thyroid functions were enrolled. All patients received IFN‐α‐2b, 3 or 5 million units thrice weekly, or pegylated (PEG)‐IFN‐α‐2b 80 or 100 µg weekly combined with ribavirin 1–1.2 g daily for 24–48 weeks. Assays for serum thyroid stimulating hormone (TSH) and free thyroxine were performed. Results: By the end of the treatment, thyroid dysfunction (TSH <0.1 or >5 mU/L) had developed in 58 patients (12.6%). Female gender was significantly associated with thyroid dysfunction (P < 0.001 odds ratio (OR) = 2.85; 95% confidence interval (CI) = 1.6–5.1). The incidence of thyroid dysfunction was similar for standard IFN and PEG‐IFN‐treated patients (49/391 vs 9/70; P = 1.00). Under a nested case‐control design, detailed laboratory assessment was carried out on frozen serum samples from patients and age‐ (± 5 years) and sex‐matched controls (n = 58). Multivariate analysis revealed significant association between higher positive rates of pretreatment TMA and patients who developed thyroid dysfunction (OR = 5.8, 95% CI = 1.2–27.9). Ten patients (～2%) remained thyroid dysfunctional at the end of follow up (median, 26.5 months). For these patients, no risk factor can predict the reversibility of thyroid function. Conclusions: Female gender and pretreatment TMA positivity are associated with thyroid dysfunction. Long‐term thyroid dysfunction may persist in a small group of patients (～2%).