Background/Purpose: Despite late tuberculosis infection (LTBI) screening before anti-TNF treatment, TB reactivation/new exposure in endemic areas remains a relevant problem. The specific analysis of Ankylosing Spondylitis (AS) and Psoriatic Arthritis (PsA) screening parameters has not been evaluated previously and may provide clues to improve risk assessment for these diseases. Our objective is to evaluate retrospectively the efficacy of LTBI screening for anti-TNF therapy in AS and PsA in endemic areas and further determine the possible distinguishing features of the LTBI parameters in each disease.

Methods: A total of 218 Spondyloarthritis patients (135 AS and 83 APS) were screened for LTBI before receiving anti-TNF treatment using the tuberculin skin test (TST), chest X-ray and history of previous TB exposure. Patients were regularly followed assessing infectious symptoms/new exposure every 2-3 months. LTBI patients were treated with isoniazid for 6 months.

Results: From June 2014 to June 2018, 135 AS and 83 PsA were referred to Immunotherapy Infusion Center to initiate anti-TNF treatment. LTBI screening was more often positive in AS than in PsA (42% vs. 30%, p=0.043). LTBI parameters were distinct in both diseases with a higher frequency of TST-positive (93% vs. 64%, p=0.002) and lower frequency of history of exposure (18% vs. 52%, p=0.027) and previous TB (0.7% vs, 6%, p= 0.03) in AS than PsA.   During follow-up, 7 (4%) AS (71% LTBI-) and 4 (5%) PsA (50% LTBI-) patients developed active TB (ADA, INF and ETA) and 45% were extrapulmonary. Four cases (3 AS and 1 PsA) occurred within the first year of anti-TNF and 2 (50%) in LTBI+ patients, suggesting reactivation. Seven cases (4 AS and 2 PsA) occurred after the first year (4 AS and 1 PsA were LTBI-) probably due to re-exposure. 

Conclusion: We report a distinct pattern of LTBI screening parameters in AS and PsA, with a higher frequency of LTBI in the former, mainly identified by TST.  For PsA, TST and a history of exposure have similar relevance for LTBI diagnosis. The frequency of screening failure remains a problem and it was comparable in AS and PsA. Availability of non anti-TNF therapies, that are not associated with an increased risk of TB reactivation, may be safer for patients with high risk of TB. Furthermore the annual periodic rescreening may benefit the re-exposure group.

« Back to 2019 ACR/ARP Annual Meeting

ACR Meeting Abstracts - https://acrabstracts.org/abstract/distinctive-pattern-of-ltbi-screening-parameters-in-ankylosing-spondylitis-as-and-psoriatic-arthritis-psa-in-endemic-areas/