Objectives: To analyse the clinical features and outcomes of patients presenting with life-threatening systemic disease in a large cohort of Spanish patients with primary Sjögren's syndrome (SS).
Methods: The GEAS-SS multicentre registry was formed in 2005 with the aim of collecting a large series of Spanish patients with primary SS, and included more than 20 Spanish reference centres with substantial experience in the management of SS patients. By January 2018, the database included 1580 consecutive patients fulfilling the 2002 classification criteria for primary SS. Severe, life-threatening systemic disease was defined as an activity level scored as "high" in at least one ESSDAI domain.
Results: Among 1580 patients, 208 (13%) were classified as presenting a severe, potentially life-threatening systemic disease: 193 presented one ESSDAI domain classified as high, 14 presented two high scored domains and only one presented three high activity domains. The ESSDAI domains involved consisted of lymphadenopathy in 78 (37%) cases, CNS in 28 (13%), PNS in 25 (12%), pulmonary in 25 (12%), renal in 21 (10%), cutaneous in 19 (9%), articular in 18 (9%), haematological in 7 (3%) and muscular in 4 (2%). Patients with severe systemic disease were more frequently men (p=0.001) and had a higher frequency of anaemia (p<0.001), lymphopenia (p<0.001), rheumatoid factor (p=0.021), low C3 levels (p=0.015), low C4 levels (p<0.001) and cryoglobulins (p<0.001). From a therapeutic point of view, systemic patients received more frequently glucocorticoids (p<0.001), immunosuppressants (p<0.001), intravenous immunoglobulins (p=0.008) and rituximab (p<0.001). We found an overall mortality rate of 20% in severe systemic patients, a rate that reached to 33% in patients presenting two or more high systemic involvements; these patients had a higher frequency of low C4 levels (p=0.012) and cryoglobulins (p=0.001) in comparison with those with a single severe organ involved.
Conclusions: 13% of patients with primary SS develop a potentially life-threatening systemic disease (mainly lymphoma, but also severe internal organ involvements including nervous system, the lungs and the kidneys). This subset of patients requires intensive therapeutic management with a mortality rate of nearly 20% of cases.