Combination of cytoplasmic and nuclear patterns on Hep-2 antinuclear antibody is useful as a screening test for anti-synthetase syndrome.

ABSTRACT

OBJECTIVE: This study aimed to establish a screening model for differentiating anti-synthetase syndrome (ASS) from other ANA-associated rheumatic diseases (AARDs) using a combination of cytoplasmic and non-cytoplasmic ANA (ncANA) patterns. METHODS: This retrospective observational study included patients with AARDs such as SLE, SSc, SS, MCTD and PM/DM who underwent ANA screening between April 2012 and December 2021. Variables included age, sex, ANA patterns (Cytoplasmic and ncANA) and titres. Logistic regression analysis of Cytoplasmic and ncANA patterns was performed to differentiate ASS from other AARDs. RESULT: The 981 diagnosed cases of AARDs consisted of SS (n = 451), SSc (n = 264), SLE (n = 201), PM/DM (n = 104), MCTD (n = 52) and ASS, including PM/DM (n = 64). Of these, 155 patients had ≥2 overlapping diseases; however, there was no overlap between AARDs and ASS. ASS is more likely to occur when the cytoplasmic titre is positive and the ncANA <320. Receiver operating characteristic analysis of the Cytoplasmic and ncANA range revealed an area under the receiver operating characteristic curve of 0.885 (95% CI 0.844-0.927). CONCLUSION: It is important to detect cytoplasmic patterns as an ANA screening test for ASS diagnosis, even if the titre is low. Additionally, combining the cytoplasmic and ncANA patterns yields more accurate ASS screening results.