OBJECTIVETo analyze the frequency of thyroid dysfunction and determine its influencing factors in chronic hepatitis C (CHC) patients treated with pegylated-interferon alpha (peg-IFNa)-2a and ribavirin (RBV) combination therapy.

METHODSA total of 194 CHC patients were treated with peg-IFNa-2a and RBV for 48 weeks. Development of thyroid dysfunction was recorded. Clinical and biological factors from pre-treatment (baseline) to post-treatment were statistically analyzed to determine correlation with thyroid dysfunction in this patient population.

RESULTSFifty-two (26.80%) of 194 peg-IFNa-2a/RBV-treated patients developed thyroid dysfunction. Dysfunction severity ranged from hyperthyroidism (n = 1, 0.52%) and hypothyroidism (n = 10, 5.15%) to subclinical hyperthyroidism (n = 4, 2.06%) and subclinical hypothyroidism (n = 37, 19.07%). The dysfunction rate was significantly higher after peg-IFNa-2a/RBV treatment (26.80% vs. 12.37% at baseline, x2 = 12.829, P less than 0.05, odds ratio (OR) = 0.386, 95% confidence interval (CI): 0.226-0.657), in females (33.00% vs. 20.21% in males, P less than 0.05, 95% CI: 1.016-3.040), and in thyroid auto-antibody positive patients (64.29% vs. 23.89% in negative patients, P less than 0.05, 95% CI: 1.681-36.183). Early virological response did not have any significant effect on dysfunction rate (23.00% vs. 30.85% no early virological response, x2 = 1.522, P more than 0.05) nor did end of treatment response (27.19% vs. 26.25% no response at end of treatment, x2 = 0.021, P more than 0.05). Patients who developed thyroid dysfunction had higher interleukin (IL)-6 at baseline (i.e. before peg-IFNa-2a/RBV treatment) (27.08+/-14.90 vs. 11.65+/-5.46 in patients who maintained normal thyroid function, t = 3.127, P less than 0.05, 95% CI: 5.28-25.58). IL-6 levels were not significantly different between the two groups at 24 weeks (6.30+/-2.47 vs. 6.81+/-2.80, t = 0.352, P more than 0.05). IL-6 levels before and after 48 weeks of treatment in normal thyroid function patients were 27.08+/-14.90 and 6.30+/-2.47, t = 3.632, P less than 0.05, and in thyroid dysfunction patients were 11.65+/-5.46 and 6.81+/-2.80, t = 1.997, P more than 0.05.

CONCLUSIONPeg-IFNa-2a/RBV combination therapy may cause thyroid dysfunction, especially hypothyroidism, in CHC patients. Female sex and thyroid auto-antibody positivity may put CHC patients at higher risk of developing thyroid dysfunction during peg-IFNa-2a/RBV therapy. Elevated IL-6 may be a predictive marker of peg-IFNa-2a/RBV-induced thyroid dysfunction.