Follow-up Testing of Interferon-Gamma Release Assays Are Useful in Ankylosing Spondylitis Patients Receiving Anti-Tumor Necrosis Factor Alpha for Latent Tuberculosis Infection

We evaluated the utility of follow-up interferon-gamma release assays (IGRAs) for the diagnosis of reactivation of latent tuberculosis infection (LTBI) or new tuberculosis in ankylosing spondylitis (AS) patients receiving anti-tumor necrosis factor alpha (anti-TNFα). The study participants (n=127) had a negative IGRA screening before receiving anti-TNFα and were evaluated by follow-up IGRA. We retrospectively examined data of the subjects according to age, gender, tuberculosis prophylaxis, concomitant medications, IGRA conversion and anti-TNFα, including type and treatment duration. The median duration of anti-TNFα was 21.5 months, and the median age was 35.3 yr. Of the 127 patients, IGRA conversion was found in 10 patients (7.9%). There was no significant variation between IGRA conversion rate and any risk factors except for age. IGRA conversion rate was not significantly different between AS and rheumatoid arthritis (P=0.12). IGRA conversion was observed in AS patients receiving anti-TNFα in Korea. A follow-up IGRA test can be helpful for identifying LTBI or new tuberculosis in AS patients receiving anti-TNFα.