High incidence of anergy in inflammatory bowel disease patients limits the usefulness of PPD screening before infliximab therapy.

Background & Aims: Reports of tuberculosis (TB) in patients administered infliximab prompted the Food and Drug Administration to recommend that all patients being considered for this therapy be evaluated for the risk for latent TB infection by means of a tuberculin skin test (TST). The aim of this study is to evaluate the utility of a TST as an adequate screen for TB exposure in patients with inflammatory bowel disease (IBD).

Methods: Eighty-two consecutive patients with IBD (Crohn's disease, 70 patients; ulcerative colitis, 4 patients; indeterminate colitis, 8 patients) seen at Cedars-Sinai Medical Center IBD Center (Los Angeles, CA) being treated with or considered for infliximab therapy underwent a standard intradermal purified protein derivative (PPD) TST before or between infusions of infliximab. One or more control antigens (Candida, tetanus, and/or mumps) were concurrently placed on 69 of these patients. Skin tests were read for induration at 48-72 hours after placement, and results were recorded.

Results: None of 82 patients had a positive PPD TST result. Overall, 71% of patients (49 of 69 patients) with controls placed failed to react to any antigen. Eighty-three percent of patients (40 of 48 patients) who were administered corticosteroids and/or immunosuppressive medications, not including infliximab, for at least 1 month were anergic compared with 43% of patients (9 of 21 patients; P < 0.002) who were not administered those medications.

Conclusions: Given the high prevalence of anergy, a negative TST result in patients with IBD administered infliximab is an unreliable indicator for TB exposure. Evaluation for TB risks should include not only a TST, but also a detailed history of travel, TB exposures, and such symptoms as chronic cough and weight loss, and a chest radiograph should be considered.