Background Primary Sjögren's syndrome (pSS) is a chronic systemic autoimmune disease often accompanied by analytical abnormalities. Altered levels in serum protein concentration, blood cell count and autoantibodies contribute to the broad spectrum of biological manifestations that characterize pSS.

Objectives The objective of this study is to evaluate the presence of laboratory abnormalities in patients with pSS from the SjogrenSER registry.

Methods We conducted a multicentre transversal study of a cohort of pSS patients fulfilling 2002 European/American criteria, from 33 Spanish rheumatology departments. Every patient was interviewed for data collection and signed an informed consent. Data were also collected by reviewing medical records. Local ethics committees approved the study. Variables were analysed by descriptive statistical methods, using means, medians and rates. Chi-square was used to establish the statistical associations. A p<0.05 was considered significant.

Results Four hundred and thirty-seven patients were included. Ninety-five percent of them were women. The median age of the cohort was 58 years. AntiRo antibodies were present in 93.6% of patients and AntiLa antibodies in 67.3% of patients. All patients were ANA+. Rheumatoid factor (RF) was positive in 64.8% of patients. Low levels of C3 and C4 were observed in 14.87% and 14.19% of patients, respectively. Polyclonal hypergammaglobulinemia (HGG) was present in 53% of patients. Thirteen patients had cryoglobulins (2.97%). An increase in β2microglobulin was observed in 22.2% of patients. Fifty-six percent of the patients had hematological involvement: 29% of the patients had anemia, 38% had leukopenia (38% lymphopenia, 10.5% had neutropenia), and 9% had thrombocytopenia. The median ESR was 25 mm. Age at diagnosis and age at onset of symptoms were significantly lower in patients presenting RF+ vs RF- (48.71 vs 53.73, p<0.001 and 44.76 vs 49.53, p=0.001, respectively), decreased C3 vs normal C3 (45.66 vs 51.18, p=0.004 and 42.2 vs 46.99, p=0.018, respectively), decreased C4 vs normal C4 (47.02 vs. 50.89, P=0.042, for age at diagnosis) and HGG (47.59 vs 54, p<0.001, and 43.44 vs 50.16, p<0.001, respectively). ESR was significantly higher in patients with hematological involvement (35.94 vs 26.24, p<0.001), RF+ (36.39 vs 22.91, p<0.001), decreased C3 (37.8 vs 30.53, p=0.026) and C4 (38.71 vs. 30.42, p=0.04)), HGG (36.21 vs 26.03, p<0.001) and increased β2microglobulin (38.80 vs 29.71, p=0.009). ESSDAI (Eular Sjögren Syndrome Disease Activity Index) was significantly higher in patients with haematological involvement (5.58 vs 3.69, p<0.001), RF+ (5.40 vs 3.53, p<0.001) and HGG (5.31 vs 3.93, P=0.011). The median ESSDAI score was 2 (P25-P75, 0–4).

Conclusions in SjogrenSER registry all patients were serologically positive. More than half of the patients presented abnormalities in serum proteins and 14% had hipocomplementemia. More than half of the patients had abnormalities, mostly leucopenia and lymphopenia. Patients with analytical alterations were younger at the time of diagnosis and had more often elevated ESR and higher ESSDAI score.

Disclosure of Interest None declared