Anti-TNF Tedavisi Öncesi Latent Tüberküloz Taramasında Tüberkülin Deri Testi ile Interferon-Gama Salınım Testinin Karşılaştırılması

Abstract

After initiation of treatment with Anti-TNF drugs, increase of the incidence of tuberculosis was observed . Particularly in countries with a high prevalence of tuberculosis, reactivation of latent tuberculosis infection constitutes a major problem for anti-TNF therapy. Before starting anti-TNF therapy, screening patients with chest X-ray, tuberculin skin test (TST), interferon-gamma release assays (IGST) is generally accepted approach. As a result of the scan, if latent tuberculosis is considered, INH prophylaxis should be started. INH prophylaxis has different severe side effects such as hepatotoxicity and neuropathy. Therefore, in order not to cause unnecessary drug exposure, prophylaxis decision for patients is important. TDT results is affected by BCG vaccination. However ınterferon-gamma release assays is less affected by these factors, so it can give more reliable result. Because BCG vaccine is routinely applied in our country, İGST screening will reduce the rate of unnecessary INH prophylaxis. In this study, comparison of the results of the TDT and interferon-gamma release tests are planned for screening latent tuberculosis before initiation of anti-TNF treatment. PATIENTS AND METHODS: 781 patients scanned with TST between 2001 and 2011 and 516 patients scanned with İGST between 2011 and 2013 were enrolled in this study. Age, gender, diagnosis, current treatment, anti-TNF treatment, TST and İGST results of the patients were obtained from HUR-BIO registry system within the Department of Rheumatology and included in the study. Chest radiographs of the patients were evaluated. İGST and TST results and the rate of initiation INH prophylaxis was compared for each group. Association between the results of the TST, İGST and age, gender, rheumatic disease, and chest radiograph findings were evaluated. In addition, compliance between İGST and TST results was assessed in 46 patients that have both the test results for screening latent tuberculosis. TST test was made by the method of Montoux and evaluated and recorded by a doctor 72 hours later. Quantiferon In Gold Tube was used for İGST. Comparison of ordinal variable groups with TST was evaluated by kruskal-wallis test and Mann-Whitney U test. Difference in frequencies between the two groups were compared with chi-square test. Compliance between TST and İGST tests was assessed by kappa test. RESULTS: 71.2% of patients had a positive TST and 21.3% of patients were found to be positive İGST. We found that if IGST was used for screening latent tuberculosis before anti-TNF therapy, initiation of prophylaxis was significantly less than TST test. There was no concordance between TST and IGST. Chest x-ray findings in IGST positive patients, sequelae changes were significantly increased. In RA patients, average TST was found significantly lower than patients with spondyloarthropathy. TST and IGST positivity rate was significantly higher in male patients. The average age of patients with negative TST and positive IGST was higher . CONCLUSIONS: As a result, latent tuberculosis infection rates were significantly lower in patients scanned with IGST. This is especially important for reducing INH prophylaxis rates. The reliability of TST is controversial for patients applied BCG vaccine. İGST test should be performed in patients vaccinated with BCG.