Background/Purpose: Risk of opportunistic infections, particularly mycobacterial infections, is increased among patients with rheumatic diseases treated with anti-TNF α agents. Therefore, screening of patients for latent tuberculosis infection (LTBI) is recommended prior to the initiation of anti-TNF α agents. However, there is a risk of seroconversion even among patients who tested negative for LTBI following treatment with anti -TNF α agents because of immunosuppression and exposure. There is paucity of data regarding the frequency of seroconversion and currently there is no clear recommendation on how often the patients should be screened for latent tuberculosis while receiving anti -TNF α agents.

Methods: We conducted a retrospective chart review of patients with various rheumatic diseases who received anti-TNF α agents from 2004 to 2014 in the VA Medical Center, Memphis TN. Patients with prior history of tuberculosis (TB) or prior treatment with TB medications were excluded. Any concomitant immunosuppressive medications including corticosteroids were also noted. We found a total of 133 patients on anti -TNF α agents, during this period, who had repeat testing for LTBI. All of these patients had tuberculosis screening test before starting anti TNF α agents either by Tuberculin Skin test (TST) or Quantiferon TB Gold Test. TB screening tests were variably repeated on these patients to evaluate for the possibility of seroconversion. Total number of TB screening tests and Chest radiographs each patient had, were also documented. We calculated incidence rate of TB screening test conversion per 100 patient year.

Results: Each of the 133 patients took anti -TNF α agents for a mean of 5.4 years (SD 3.25) and had mean of 3.6 (SD 1.57) TB screening tests. Only 1 out of 133 patients converted from negative TST to positive TST. This gentleman had seropositive Rheumatoid arthritis managed with Infliximab and Methotrexate for 6 years and 2 months before converting to positive TST. Risk of conversion of TB screening test was calculated as 0.138 per 100 patient year.

Conclusion: Risk of conversion of TB screening tests while on anti -TNF α agents was found to be very low in our veteran population. This is much lower than what has been reported in the literature and worth reporting. We conclude that repeat testing on a scheduled basis is not necessary among low risk patients.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/conversion-rate-of-tuberculosis-screening-tests-in-patients-with-rheumatic-diseases-while-receiving-anti-tumor-necrosis-factor-alpha-anti-tnf%ce%b1-agents/