QuantiFERON-TB Gold plus testing for the detection of LTBI among health care workers in major TB hospitals of the Northern Kyrgyz Republic

BACKGROUND: Health care workers (HCW) are at increased risk of TB infection due to their close contact with infected patients with active TB. The objectives of the study were (1) to assess the prevalence of LTBI among HCW in the Northern Kyrgyz Republic, and (2) to determine the association of LTBI with job positions or departments. METHODS: HCWs from four TB hospitals in the Northern Kyrgyz Republic were tested with the interferon-gamma release assay (IGRA) Quantiferon-TB Gold plus (QFT) for the detection of an immune response to TB as marker of TB infection. Age was controlled for as a confounder. Univariate and multivariable analysis were performed using logistic regression to assess the association of the risk factors (job position, and department) with having a QTF positive result. Firth’s penalized-likelihood estimates were used to account for the small-sample size. Pairwise comparisons using the Bonferroni correction (conservative) and comparisons without adjusting for multiple comparisons (unadjusted) were used to identify the categories where differences occurred. RESULTS: QFT yielded valid results for 404 HCW, with 189 (46.7%) having a positive test. In the National Tuberculosis Center there was an increased odds to have a positive QFT test for the position of physician (OR = 8.7, 95%, CI = 1.2–60.5, p = 0.03) and laboratory staff (OR = 19.8, 95% CI = 2.9–135.4, p < 0.01) when administration staff was used as the baseline. When comparing departments for all hospitals combined, laboratories (OR 7.65; 95%CI 2.3–24.9; p < 0.001), smear negative TB (OR 5.90; 95%CI 1.6–21.8; p = 0.008), surgery (OR 3.79; 95%CI 1.3–11.4; p = 0.018), and outpatient clinics (OR 3.80; 95%CI 1.1–13.0; p = 0.03) had higher odds of a positive QFT result than the admin department. Fifteen of the 49 HCW with follow-up tests converted from negative to positive at follow-up testing. CONCLUSIONS: This is the first report on prevalence and risk factors of LTBI for HCW in the Kyrgyz republic, and results indicate there may be an increased risk for LTBI among physicians and laboratory personnel. Further research should investigate gaps of infection control measures particularly for physicians and laboratory staff and lead to further improvement of policies.