Background: The aims of the present study were to analyze the clinical and immunologic characteristics of a wide group of patients with systemic lupus erythematosus (SLE) and define homogeneous subgroups with their own characteristics.
Methods: A prospective study of 300 patients diagnosed of SLE were studied. These patients were subdivided according to sex, age at the onset of the disease and immunologic profile. The statistical study was carried out by the chi (2), Fisher, Student's t and Mann-Whitney U tests.
Results: The series was made up of 266 (89%) females and 34 (11%) males. The mean age at onset of the disease was 31.8 +/- 14.6 years. In 48 (16%) patients the first manifestations appeared after the age of 50. Males were shown to present a lower prevalence of arthritis (59% vs 82% in woman, p < 0.005) and malar rash (29% vs 50%, p < 0.05), but had more cutaneous discoid lesions (18% vs 3% p < 0.001). In patients in whom the disease appeared after the age of 50 a lower prevalence of arthritis was presented (67% vs 82% in patients of less than 50 years of age, p < 0.005), malar rash (23% vs 53%, p < 0.001) and nephropathy (21% vs 41%, p < 0.05), but had greater myositis (17% vs 6%, p < 0.01). The absence of antinuclear antibodies (ANA) and the presence of anti-ds DNA and anti-ENA antibodies were associated with differences in the prevalence of different clinical manifestations.
Conclusions: Sex, age and immunologic pattern in systemic lupus erythematosus permit the definition of homogeneous subgroups with their own characteristics: a) males present a lower prevalence of arthritis and malar rash, but a greater prevalence of cutaneous discoid lesions; b) patients over the age of 50 develop arthritis, malar rash and nephropathy with a lower prevalence but have a greater prevalence of myositis; c) patients without antinuclear antibodies and those with anti-ds DNA and anti-ENA antibodies present differences in the prevalences of different clinical manifestations.