Clinical and serological characteristics of anti-Ro/SS-A and anti-La/SS-B negative primary Sjögren's syndrome: a comparative study.

OBJECTIVE: This study aimed to describe the clinical spectrum of primary Sjögren's syndrome (pSS) patients with anti-Ro/SS-A and anti-La/SS-B negativity.

PATIENTS AND METHODS: From a single-center study population of consecutive SS patients fulfilling the 2016 ACR-EULAR classification criteria, those with triple seronegativity anti-Ro/SS-A (anti-Sjögren's-syndrome-related antigen A autoantibody), anti-La/SS-B (anti-Sjögren's-syndrome-related antigen B autoantibody), rheumatoid factor (RF) (-) and antinuclear antibody (ANA)(+)] or [anti-Ro/SS-A(-), anti-La/ SS-B(-), RF(+) and ANA(-)] and quad¬ruple seronegativity [anti-Ro/SS-A(-), anti-La/SS-B(-), RF(-) and ANA(-)] were identified retrospectively. Clinical, serological, and laboratory features were compared. A comparison between triple and quadruple seronegative pSS patients was also performed.

RESULTS: We included 184 patients (168 women, 16 men) with a mean age at diagnosis of 50.1±13.1 years. The most common subjective presenting features at the time of the diagnosis were dry mouth (94.5%) and dry eye (91.3 %). ANA positivity was 57.0%, and RF positivity was 30.4%. Salivary gland enlargement, arthritis, Raynaud's phenomenon, vasculitis, interstitial lung disease (ILD), neurological involvement, primary biliary cholangitis (PBC), lymphopenia, and thrombocytopenia were observed in ANA+ and RF+ patients but not in seronegative patients (p<0.0001). Arthritis was observed most frequently in RF-positive patients and secondly in ANA-positive patients, whereas arthritis was not observed in seronegative patients (p<0.0001). Autoimmune thyroiditis was present in 65 patients (35.0%), 84.6% of these patients were ANA positive while 12.3% were ANA negative (p=0.0014), RF positivity was 30.7% while RF negativity was 6.15% (p=0.001), 23.0% were both ANA and RF positive while 12.3% were seronegative (p<0.002). Cryoglobulinemia, renal disease, and lymphoma were not observed in any of the patients.

CONCLUSIONS: We confirm the strong influence of immunological markers on the phenotype of primary SS at diagnosis.