Impact of latent tuberculosis treatment on the risk of mycobacterium tuberculosis (MTB) in seropositive rheumatoid arthritis initiating TNF inhibitors in an MTB endemic area

Dear Editor, Current guidelines recommend that all patients undergoing tumor necrosis factor inhibitors (TNFI) treatment are screened for latent tuberculosis infection (LTBI) and receive appropriate treatment before initiating TNFI [1]. However, there are no well-designed real-world studies proving the effectiveness of this guideline for rheumatoid arthritis (RA) patients in a mycobacterium tuberculosis (MTB) endemic area, such as South Korea. This study investigates whether TNFI increases the risk of MTB development in the era of LTBI treatment in RA patients. We followed a population-based, longitudinal cohort of seropositive RA patients receiving TNFI using data from the Korean National Health Insurance Service (NHIS) and compared this cohort with 1:4 matched untreated RA patients in a MTB endemic area in South Korea. We retrieved data from the NHIS database [2, 3] from 1 January 2007 to 31 December 2016. A washout period from 1 January 2007 to...