Seronegative primary Sjögren’s syndrome, a distinct subtype of primary Sjögren’s syndrome in Chinese patients

Abstract Background To investigate the clinical and immune characteristics of patients with primary Sjögren’s syndrome (pSS) who were negative for anti–Sjögren’s-syndrome-related antigen A antibodies (anti-SSA) and anti–Sjögren’s-syndrome-related antigen B antibodies (anti-SSB) in Chinese population. Methods A retrospective study were performed and 232 patients with pSS were analyzed. Patients positive for anti-SSA or/and anti-SSB were termed as seropositive pSS, and these negative for both anti-SSA and anti-SSB (non-antinuclear antibodies) as seronegative pSS. Clinical manifestations and laboratory findings were compared between the two groups. Results Among the 232 patients with pSS, 192 (82.8%) were seropositive pSS and 40 (17.2%) were seronegative pSS. Compared to seropositive pSS, seronegative pSS were older and with higher percentage of low disease activity (ESSDAI