Clusters of Clinical and Immunologic Features in Systemic Lupus Erythematosus: Analysis of 600 Patients from a Single Center

Objective: To analyze the prevalence and characteristics of the main clinical, hematologic, and immunologic manifestations of systemic lupus erythematosus (SLE) in a cohort of 600 consecutive patients from a single center, and to determine the specific characteristics of organ involvement in a homogeneous SLE population.

Methods: Patients were consecutively seen in our department either as inpatients or outpatients between 1980 and 2001. All had documented medical histories and underwent a medical interview as well as a routine general physical examination. Clinical and serologic characteristics of all patients were consecutively collected in a protocol form.

Results: The final cohort (survival cohort) consisted of 533 (89%) women and 67 (11%) men (female to male ratio, 8:1), with an average of 29 new patients per year. Mean age at onset of symptoms attributable to the disease was 31 years (range, 5 to 84 years) and mean age at the time of diagnosis of SLE was 33 years (range, 6 to 85 years). The most frequent SLE involvement was articular involvement, found in 498 patients (83%), followed by hematologic involvement in 451 patients (75%), specific SLE cutaneous involvement in 354 patients (59%), constitutional features in 252 patients (42%), and nephropathy in 203 patients (34%). Patients enrolled in the protocol before 1991 had a higher frequency of central nervous system (CNS) involvement (27% vs 10%, P <.001), thrombotic events (17% vs 9%, P =.003), and abnormal hematologic parameters (85% vs 66%, P <.01), but a lower frequency of articular involvement (79% vs 86%, P =.038) than those enrolled after 1991. The following were observed associations: specific SLE cutaneous involvement was associated with anti-Sm antibodies; renal involvement with hemolytic anemia and anti-double-stranded DNA antibodies; CNS involvement with thrombocytopenia and immunoglobulin G-anticardiolipin; thrombotic events with low total hemolytic complement, immunoglobulin G-anticardiolipin, and lupus anticoagulant; and myositis with anemia and anti-ribonucleoprotein antibodies.

Conclusion: This large study, performed in a single center, has shown cluster associations between certain clinical, hematologic, and immunologic features of SLE, reflecting specific patterns of disease expression. The accurate evaluation of clinical features and laboratory markers at disease diagnosis and during evolution may improve the clinical treatment of SLE patients.