The differential role of SSa/SSb and Ro52 antibodies in defining clinical phenotypes in idiopathic inflammatory myopathies.

ABSTRACT

OBJECTIVE: In idiopathic inflammatory myopathies, anti-SSa/SSb and anti-Ro52 are associated with interstitial lung disease (ILD), yet few studies have compared their prognostic utility. Our study analyzes clinical phenotypes associated with anti-SSa/SSb and anti-Ro52 positivity in IIM and their association with ILD. METHODS: We performed a retrospective analysis of IIM patients >18-years-old, seen at Northwell Myositis Center 2007- 2018 who met 2017 EULAR/ACR criteria with available anti-SSa/SSb data. Patients who were anti-SSa/SSb(-) and anti-Ro52(+) were excluded from anti-SSa/SSb subgroup analysis but included in Ro52 subgroup analysis. Organ manifestations, pulmonary function tests (PFTs) and comorbidities were recorded. Statistical analyses included Chi-square, Fisher's Exact, Wilcoxon Rank Sum, McNemar's test. RESULTS: Of 94 patients included in the final analysis, 35% (33/94) were anti-SSa/SSb positive (+). Of 60 patients with anti-Ro52 data, 42% (25/60) were (+). ILD was more common in anti-SSa/SSb (+) versus anti-SSa/SSb negative patients and anti-Ro52(+) versus anti-Ro52 negative patients (58% vs 25%; p = 0.003 and 64% vs.26%; p = 0,004 respectively). Anti-SSa/SSb (+) was not associated with increased ILD severity based on PFTs. Anti-Ro52(+) group had lower DLCO than anti-Ro52(-) (47% vs 68%; p = 0.003). Anti-SSa/SSb positivity did not confer a difference in the frequency of other manifestations. Elevated rates of venous thromboembolism (VTE) (10%-12%) and osteoporosis (13-17%) were observed independent of anti-SSa/SSb or anti-Ro52 status. CONCLUSION: In IIM anti-SSa/SSb or anti-Ro52 positivity is associated with higher ILD rate. Both assays are useful to confer ILD risk, but anti-Ro52 is more predictive of severe ILD. High frequencies of osteoporosis and VTE were observed in all subgroups.