Background Primary Sjogren Syndrome (pSS) and Systemic Lupus Erythematosus (SLE) express a significant overlap in their clinical and immunological aspects. Moreover, SS often presents clinical and immunological manifestations included in the SLE classification criteria. A secondary SS (diagnosis according to AECG criteria) has been described in about 9-19% of SLE cases. Few data is available regarding the prevalence of a true overlap of the two disorders.
Objectives To investigate the prevalence of patients with pSS who can be classified as having an overlap syndrome with SLE considering both the 1997-revised ACR criteria and the new criteria proposed in 2012 by the Systemic Lupus International Collaborating Clinics (SLICC).
Methods Charts from patients with pSS (diagnosis according to AECG criteria) were retrospectively evaluated in order to collect clinical and laboratory data.
Results Two-hundred seventy patients with pSS [8M, 262 F, mean age 57.8±12,5 years, mean age at diagnosis 52.6 years ±12.5, mean follow-up 5.6 years (range 0–42 years)] were considered. Taking into account the 1997-ACR criteria, 11 patients (4.1%) could be classified as having an overlap with SLE (SS-SLE). Considering the new SLICC criteria, the number of patients raise to 18 (6.7%). Both considering the old and the new criteria, the most frequent items satisfied by the SS-SLE group were: ANA, leukopenia, oral ulcer and arthritis (Table). The items responsible for the increasing number of patients fulfilling the new criteria were low complement and the presence of leukopenia, thrombocytopenia or hemolytic anemia since these are considered separately in the new criteria. Compared to the remaining patients with pSS (246 F, 8M, mean age at diagnosis 53.3±12.4 years), the SS-SLE group (18 F, mean age at pSS diagnosis 47.9±13.1 years) showed a significantly higher frequency of leukopenia (77.7% in SS-SLE vs 14.2% in pSS; p<0.001), arthritis (44.4% in SS-SLE vs 10.3% in pSS; p<0.001) and low complement (38.8% in SS-SLE vs 7.14% pSS; p<0.001).
Conclusions The occurrence of a true overlap between SS and SLE is relatively infrequent and the new SLICC criteria may allow a higher sensitivity to detect such condition. The items responsible for the increased sensitivity are both the introduction of hyopocomplementemia and the separate consideration of different hematological disorders in the new classification criteria. In patients with SS-SLE, hypocomplementemia, leukopenia and arthritis appear to be the most frequent manifestations.
Disclosure of Interest None declared