Objective: To assess the incidence of thyroid dysfunction (TD) in a UK cohort of patients with hepatitis C virus (HCV) infection treated with interferon-alpha (IFNalpha) and ribavirin combination therapy (IFN/RBV).
Design, patients and measurements: A retrospective study of 288 patients who received IFN/RBV for HCV during a 2-year period from January 2006 was performed. Thyroid function was assessed during a 24-week or 48-week course of IFN/RBV. If serum thyrotrophin (TSH) became undetectable (<0.01 mU/l) and serum free thyroxine (T4) was raised, a diagnostic thyroid isotope scan was performed.
Results: Full medical records were examined for 260 patients (172 men, 88 women) included in the study, of whom 22.3% (16.9% of men, 33.0% of women) developed TD during IFN/RBV. In total, 10.4% developed a suppressed serum TSH (0.8% Graves' disease, 9.6% transient thyroiditis) while 11.9% developed an elevated serum TSH with 1.5% becoming permanently hypothyroid and requiring levothyroxine therapy. Women had a relative risk (RR) for developing TD of 1.96 (CI: 1.75-3.03, P = 0.004). A serum TSH > or =1.75 mU/l and a positive thyroid peroxidase (TPO) antibody titre pretherapy were associated with RRs for progression to TD of 6.02 (CI: 2.95-12.78, P < 0.0001) and 4.35 (CI: 2.58-6.52; P < 0.0001), respectively, while combination of baseline TSH and TPO antibody data predicted progression to TD with a sensitivity of 94.7%.
Conclusions: Although TD was common in this cohort, just 2.3% developed TD that required ongoing therapy. Pre-IFN/RBV serum TSH and TPO antibody titre were found to predict progression to TD in this group of patients.