Analysis of Indeterminate QuantiFERON Assay Results in Solid Organ Transplant Candidates and Proposed Management Algorithm.

Abstract

Background: Identification and treatment of latent tuberculosis infection (LTBI) mitigate the risk of tuberculosis (TB) reactivation after transplantation. TB reactivation is higher in those with indeterminate QuantiFERON (QFT) than those with negative results. Management of indeterminate QFT results in the pretransplant period remains unclear.

Methods: We conducted a retrospective study of solid organ transplant (SOT) recipients, 18 y and older, who were screened with QFT assay pretransplantation at Mayo Clinic between January 2010 and June 2023. We examined the frequency of indeterminate QFT results, results of repeat LTBI screening, treatment decisions, and rate of posttransplant TB infection.

Results: Of 13 008 patients screened for LTBI before SOT, 736 (6%) patients had indeterminate QFT results. Among these, 247 (34%) underwent a second LTBI screening test, and 39 (5%) received LTBI treatment. Among 247 patients with a repeat LTBI screening test, 185 (75%), 48 (19%), and 14 (6%) were tested by QFT, T-SPOT.TB, or TST, respectively. The repeat QFT remained indeterminate in 160 (86%) patients, whereas all T-SPOT.TB results were negative. Posttransplant TB infection occurred in 2 (0.3%) patients; neither had a second TB screening test pretransplant nor received LTBI treatment.

Conclusions: In SOT recipients with indeterminate QFT results at pretransplant evaluation, opting for T-SPOT.TB as a second test may be preferable over repeat QFT. TB infection after transplantation in patients with a pretransplant indeterminate QFT result was rare. Patient management and LTBI treatment in those with indeterminate QFT pretransplant should account for epidemiological risk factors, and shared decision-making is recommended.