LAUSR

With the promising efficacy and the prevalent use of anti-tumor necrosis factor-α (TNF) agents in managing AS, the risk for reactivation of latent tuberculosis infection (LTBI) still is a concern. Although guidelines include the screening and treatment of LTBI prior to the initiation of anti-TNF agent by QuantiFERON-TB Gold (QFT-G) or tuberculin test, there is a lack of evidence whether treatment of LTBI before initiation of anti-TNF agent may reduce the risk of reactivation to the same as LTBI patient without anti-TNF agent or anti-TNF agent users without LTBI. Furthermore, evidence on the need for follow-up testing and the association between seroconversion and the development of active tuberculosis is also limited.This study aims to investigate the real-world impact of QFT-G test on the development of active tuberculosis in patients with AS.This retrospective study investigated 2,930 patients who had a diagnosis of AS and conducted QFT-G testing during the period of March 1998 to June 2019. 191 patients with history of treatment for LTBI or acute tuberculosis prior to the first QFT-G test and 157 patients whose hospital visits or prescription was less than 3 were excluded. Observational period was defined from the firs QFT-G test to the last hospital visit of development of active tuberculosis. The screening for development of active tuberculosis was conducted by reviewing the diagnosis, prescription of anti-tuberculosis medication, chest images and electronic medical record. Treatment of LTBI was defined when a patient was prescribed isoniazid for at least 220 for 12 months, rifampin for at least 90 days for 6 months, or concurrently prescribed isoniazid and rifampin for at least 70 days for 4 months. Wilcoxon rank-sum test, chi-square test and cox-proportional hazard analysis were performed.A total of 2687 patients (median age 32.7 years, 78.4% male, anti-TNF agent user 16.7%) were included. Baseline QFT-G was positive in 426 (20.3%) patients, and 15 active tuberculosis was observed [Incidence rate 1.5/1000 person years (PY)]. Compared with baseline QFT-G (-) patients, baseline QFT-G (+) patients were older (41.2 years vs. 31.3 years, p<0.001) and they were accompanied with more active tuberculosis (4.4/1000PY vs. 1.0/1000PY) despite the less usage of anti-TNF agents (38.5% vs 45.8%, p=0.006). The observational period, sex, and medication utilization pattern except anti-TNF agent were similar between two groups. Multivariable analysis showed that QFT-G (+) test increases the risk of active tuberculosis more than 10 times [adjusted hazard ration 17.0, 95% confidence interval (CI) 5.1-56.8, p<0.001] after adjusting age, sex and the usage of anti-TNF agents.Then we conducted subgroup analysis on 965 patients with baseline QFT-G (-) and follow-up QFT-G tests. Seroconversion was documented in 65 patients (6.7%). Active tuberculosis was observed in 4 patients, and seroconversion was occurred before the development of active tuberculosis in all patients. The incidence of active tuberculosis in seroconversion patients were 10.5/1000PY.QFT-G (+) and QFT-G seroconversion is associated with increased risk of the development of active tuberculosis in patients with AS.Figure 1.Overview of patient flowNone declared