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.