Risk of tuberculosis in dialysis population: Revising the predictive value of interferon-gamma releasing assay

Abstract

Background: Patients on long-term dialysis are at high risk for tuberculosis (TB) and latent tuberculosis infection (LTBI) is good target for future TB eradication. However, interferon-gamma release assay-defined LTBI has high proportion of negative conversion and lacks of active TB correlation in dialysis population. Design: Patients on long-term dialysis were screened in multiple centers in Taiwan. QuantiFERON-TB Gold In-tube (QFT-GIT) was used to define LTBI and was performed every six months for three times. Primary outcome was active TB diagnosed after LTBI screen and we analyzed the incidence and predictive value by QFT-GIT. Results: We totally enrolled 940 dialysis patients with average age of 59.3 years and dialysis duration of 5.5 years. Initial QFT-GIT results were positive in 193 patients, of whom positive results persisted in 49.6% at second check. In an average follow-up period of 3 years, seven patients had TB. Three (319.1 per 100,000 persons) and four (141.8 per 100,000 person-years) of them were prevalent and incident TB cases, respectively. Persistent positive QFT-GIT for twice and thrice correlated increasing HR (14.44 and 20.29, respectively) for TB development in comparing with once positive (HR: 10.38). TB incidence was up to 1352.3 per 100,000 patient-years among those with thrice positive QFT-GIT. Conclusions: In an intermediate prevalent area, dialysis patients have high TB risk and persistent LTBI status predicts TB development more specific than once positive for LTBI. After excluding prevalent TB cases, serial follow-up of LTBI could narrow the target population to reduce cost for LTBI treatment.