Use of the QuantiFERON-TB Gold interferon-gamma release assay for screening transplant candidates: a single-center retrospective study.

BACKGROUND

Tuberculosis (TB) reactivation is a rare but significant complication of organ transplantation, and screening of all transplant candidates for latent infection is recommended with either an interferon-γ release assay (IGRA) or tuberculin skin test (TST).

METHODS

After institutional review board approval, we retrospectively collected data to describe the yield of transplant candidate screening using the QuantiFERON-TB Gold (QFT) and QuantiFERON-TB Gold In-Tube (QFT-IT) assays since the institution of TB screening in 2008 and the epidemiology of all cases of post-transplant TB in our institution since 2004.

RESULTS

A total of 2392 patients were screened with either the QFT or QFT-IT assay through October 2009; 245 (10.2%) tested positive and 206 (8.6%) were indeterminate. Of those with positive results, 107 (43.7%) were foreign born and most of the remainder had prior TB exposures. Of the tests performed at a reference lab, 29% were indeterminate, whereas 14% were indeterminate using our in-house lab. The majority of indeterminate results were seen in liver transplant candidates (40.6% vs. 11.8% in non-liver candidates). Three of 694 (0.43%) screened patients who underwent transplantation developed TB post transplant.

CONCLUSIONS

Post-transplant TB occurs at a low rate with universal IGRA-based candidate screening, which is comparable to studies using TST screening.