Comparison of quantiferon-tb gold with tuberculin skin test for detection of latent tuberculosis infection before kidney transplantation

Introduction Screening for latent tuberculosis infection (LTBI) before kidney transplantation (KT) is an indispensable process, purposes of this study were to compare the QuantiFERON-TB Gold In-Tube test (QFT-GIT) with the tuberculin skin test (TST) for screening of LTBI in kidney transplant recipients (KTRs). Methods We compared prospectively the results of QFT-GIT with TST in 97 KTRs screened for LTBI between July 2008 and July 2012. Isoniazid (INH) prophylaxis was applied to KTRs with a positive TST or positive QFT-GIT or clinical risk factors for LTBI. Post-transplant tuberculosis (TB) was diagnosed by clinical evidence. Results The mean patients follow-up was 24.6 ± 14.4 months. Positive results on QFT-GIT and TST was obtained among 19 (20.4%) and 12 (12.9%) subjects, respectively, an overall agreement of 79.3% (κ = 0.27, 95% confidence interval [CI] -0.03-0.50; P <.014). The incidence of TB was 0.52 per 100 person-years (95% CI 0.02-3.68). None of the patients in the INH prophylaxis group developed TB, whereas 1 in the no prophylaxis group developed disease at 14 months after KT. Sensitivity of the 2 tests could not be compared because patients who showed positive results on QFT-GIT or TST did not develop TB. The difference of specificity between QFT-GIT (79.3%) and TST (86.9%) was not significant (P =.l67). Abnormal chest radiographs (odds ratio [OR] 27.94, 95% CI 1.22-636.61, P =.037) and positive TST (OR 7.65, 95% CI 1.75-33.30, P =.007) showed significant associations with positive QFT-GIT results. Only positive QFT-GIT (OR 6.03, 95% CI 1.51-24.01, P =.011) showed an association with positive TST results. Conclusions QFT-GIT and TST for diagnosis of LTBI in KTRs showed reasonable concordance but no superiority of either test.