Risk factors for false-negative results of T-SPOT.TB and tuberculin skin test in extrapulmonary tuberculosis.

Purpose T-SPOT.TB, a recently developed T cell-based assay, has shown promise in diagnosing extrapulmonary tuberculosis (EPTB). However, a limited number of reports have compared the risk factors for false-negative results of tuberculin skin tests (TSTs) and T-SPOT.TB assays in patients with EPTB. We, thus, conducted a prospective, blinded, observational study to evaluate the risk factors for false-negative T-SPOT.TB and TST results in patients with EPTB.