Optimal testing choice and diagnostic strategies for latent tuberculosis infection among U.S.-born people living with HIV.
BACKGROUND: Increased risk of progression from latent tuberculosis infection (LTBI) to tuberculosis (TB) disease among people living with HIV (PLWH) prioritizes them for LTBI testing and treatment. Studies comparing the performance of interferon gamma release assays (IGRAs) and the tuberculin skin test (TST) among PLWH are lacking. METHODS: We used Bayesian latent class analysis to estimate the prevalence of LTBI and diagnostic characteristics of the TST, QuantiFERON Gold In-Tube (QFT), and T.SPOT-TB (TSPOT) among a prospective, multicenter cohort of U.S.-born PLWH ≥5 years old with valid results for all three LTBI tests using standard U.S. cutoffs (≥5mm TST, ≥0.35 IU/mL QFT, ≥8 spots TSPOT). We also explored the performance of varying LTBI test cutoffs. RESULTS: Among 1510 PLWH (median CD4+ count 532 cells/mm3), estimated LTBI prevalence was 4.7%. TSPOT was significantly more specific (99.7%) and had a significantly higher positive predictive value (90.0%, PPV) than QFT (96.5% specificity, 50.7% PPV) and TST (96.8% specificity, 45.4% PPV). QFT was significantly more sensitive (72.2%) than TST (54.2%) and TSPOT (51.9%); negative predictive value of all tests was high (TST 97.7%, QFT 98.6%, TSPOT 97.6%). Even at the highest cutoffs evaluated (15mm TST, ≥1.00 IU/mL QFT, ≥8 spots TSPOT), TST and QFT specificity was significantly lower than TSPOT. CONCLUSIONS: LTBI prevalence among this cohort of U.S.-born PLWH was low compared to non-U.S. born persons. TSPOT's higher PPV may make it preferable for testing U.S.-born PLWH at low risk for TB exposure and with high CD4+ counts.
Pettit, AC; Stout, JE; Belknap, R; Benson, CA; Séraphin, MN; Lauzardo, M; Horne, DJ; Garfein, RS; Maruri, F; Ho, CS; Tuberculosis Epidemiologic Studies Consortium (TBESC),
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