Utility of the interferon-gamma release assay for latent tuberculosis infection screening among indian health-care workers

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Indian Journal of Community Medicine

Background: The utility of interferon-gamma release assays (IGRAs) for latent tuberculosis infection (LTBI) screening among health-care workers (HCWs) in low- and middle-income countries (LMICs) remains unclear.

Methods: This was a prospective cohort study among HCW trainees undergoing annual LTBI screening via tuberculin skin test (TST) and QuantiFERON® TB Gold Test-in-tube (QFT-GIT) in Pune, India. TST induration ≥ 10 mm and QFT-GIT ≥ 0.35 IU/ml were considered positive. Test concordance was evaluated at entry among the entire cohort and at 1 year among baseline TST-negative participants with follow-up testing. Overall test agreement was evaluated at both timepoints using the kappa statistic: fair (k < 0.40), good (0.41 ≥ k ≤0.60), or strong (k > 0.60).

Results: Of 200 participants, prevalent LTBI was detected in 42 (21%) via TST and 45 (23%) via QFT-GIT; QFT-GIT was positive in 27/42 (64%) TST-positive and 18/158 (11%) TST-negative trainees. Annual TST conversion was 28% (40/142) and included 11 trainees with baseline TST-/IGRA+; QFT-GIT was positive in 17/40 (43%) TST-positive and 5/102 (5%) TST-negative trainees. Overall test concordance was 84% (k = 0.52; 95% confidence interval [CI]: 0.38–0.66) and 80% (k = 0.44; 95% CI: 0.29–0.59) at baseline and 12 months, respectively.

Conclusions: We observed good overall agreement between TST and QFT-GIT, and QFT-GIT detected additional LTBI cases among TST-negative trainees with possible early detection of LTBI conversion. Overall, our results support the use of IGRA for annual LTBI screening among HCWs in a high burden LMIC setting.

Girish S, Chandanwale A, Kinikar A, Pardeshi GS, Shelke S, Basavaraj A, Kadam D, Joshi S, Dhumal G, Lokhande N, Deluca A, Gupte N, Gupta A, Mave V, Bollinger R. The utility of interferon gamma release assays as tuberculosis infection screening tool in health care worker. Indian Journal of Community Medicine. 2021 Apr-Jun;46(2).