Characteristics of Sjogren's syndrome in rheumatoid arthritis

Objective. To compare features of SS in RA with primary SS and RA without SS.Methods. Patients hospitalized between January 2007 and December 2010 were retrospectively studied. Seventy-four cases of overlap RA and SS (RA/SS) among 509 cases of RA were identified. Cases of SS (n = 187) detected during the same period acted as controls.Results. Among those with RA/SS, there were 46 cases of RA-onset SS and 12 cases of SS-onset RA. Sixteen patients had simultaneous-onset RA and SS. Compared with RA without SS, RA/SS patients had more severe arthritis; a higher incidence of haematological abnormality, fever and rash; and a higher frequency of RF, ANAs and anti-SSA and anti-SSB antibodies (P <0.05). Compared with primary SS, RA/SS patients were older, had more severe arthritis, anaemia and lung involvement; a lower incidence of fever, rash, leucopenia, thrombocytopenia and hyperthyroidism; and a higher frequency of RF, anti-keratin antibody, anti-perinuclear factor and anti-cyclic citrullinated antibodies (P <0.05). Compared with RA and primary SS, RA/SS patients had higher disease activity scores of both RA and SS.Conclusion. RA/SS patients have distinctive features, with more complications and systemic involvement. In addition, disease activity is higher in RA/SS.