Etanercept therapy in patients with a positive tuberculin skin test

Etanercept (Enbrel), a tumor necrosis factor-alpha (TNF-alpha) antagonist, is commonly used for the treatment of a variety of rheumatic diseases. Tuberculosis (TB) infections have been associated with chronic TNF-alpha blocking therapy, and there is concern that such therapy may predispose patients to TB reactivation. In this study, we attempted to evaluate the frequency of latent TB reactivation among patients treated with etanercept.

All patients with either a positive purified protein derivative (PPD) for TB or a previous history of therapy for latent TB infection (LTBI) who were prescribed etanercept in the division of rheumatology at John H. Stroger Jr Hospital of Cook County prior to November 2005 were enrolled in this study. A retrospective chart review was performed looking for evidence of active TB infection during etanercept treatment.

Forty-eight patients with a positive PPD were treated with etanercept, and followed for an aggregate of 818 patient-months of etanercept exposure, with a mean follow-up period of 17 months (range 5 to 48 months); all patients had at least one follow-up visit. Forty-four patients (92%) were fully or partially treated with LTBI therapy prior to initiation of etanercept. Chest roentgenograms were available for review in 43 patients, ten of which had evidence of old granulomatous disease. No cases of active TB were described during the study period.

In this small retrospective analysis, none of the 48 patients with positive PPDs who were treated with etanercept for average of 17 months developed active TB.