Clinical and serologic features of primary Sjögren's syndrome concomitant with autoimmune hemolytic anemia: a large-scale cross-sectional study.

Autoimmune hemolytic anemia (AIHA) is an uncommon but clinically significant disorder in primary Sjögren's syndrome (pSS). Among 565 pSS patients hospitalized in Peking University People's Hospital from January 2000 to March 2013, 16 patients were diagnosed with AIHA (2.8% prevalence). AIHA presented at the onset of pSS without overt sicca symptoms in 3 of the 16 patients. Primary biliary cirrhosis (PBC) was more prevalent in the patients with SS-AIHA than in those without (p = 0.007). Edema, fever, and liver involvement occurred significantly more frequently in pSS patients with AIHA than those without AIHA (p = 0.035, p = 0.029, p = 0.024, respectively). The pSS patients with AIHA were more vulnerable to leukopenia and thrombocytopenia than those without AIHA (p = 0.004 and p = 0.001, respectively). Additionally, the levels of complement component 3 (C3) and complement component 4 (C4) were significantly lower in the SS-AIHA group (p = 0.008 and p = 0.037, respectively). Taken together, our results indicate that pSS should be considered in the differential diagnosis of AIHA, even in the absence of sicca symptoms. Among pSS patients, the existence of PBC, cytopenia, or hypocomplementemia suggests a higher risk of suffering from AIHA.