Late onset systemic lupus erythematosus in southern Chinese

Systemic lupus erythematosus (SLE) is a multisystem disorder that predominately affects women of the reproductive age. Onset of the disease beyond the age of 50 years is unusual. This study was undertaken to compare retrospectively the clinical and laboratory features between early and late onset (onset of disease beyond the age of 50 years) SLE patients in a Chinese population.

Case records of all SLE patients who attended our rheumatology clinics between 1971 and 1997 were reviewed. Patients with a disease onset beyond the age of 50 years were identified. One hundred consecutive SLE patients who had their disease onset before the age of 50 were recruited as controls. The presenting clinical features, autoantibody profile, number of major organs involved, number of major relapses, and the use of cytotoxic agents in the two groups of patients were obtained and compared.

25 patients with late onset SLE were identified. All the female patients in the late onset group were postmenopausal. The female to male ratio was 3.2 to 1, compared with 13.3 to 1 in the control group (p < 0.02). Both groups had a comparable duration of disease. There were no significant differences in the presenting features between the two groups except for a lower prevalence of malar rash (24% v 86%, p < 0.0001) and a higher prevalence of rheumatoid factor (32% v 1%, p < 0.0001) in the late onset patients. On subsequent visits, the late onset group had a lower prevalence of lupus nephritis (4% v 51%, p < 0.001), fewer major organs involved (mean number of major organs involved; 0.3 v 0.9, p < 0.02), fewer major relapses (mean number of major relapses/patient; 0.08 v 0.47, p < 0.002, number of major relapses/patient year; 0.009 v 0.12, p < 0.001), and required fewer cytotoxic agents for disease control (percentage of patients on cytotoxic agents; 32% v 79%, p < 0.002).

Late onset SLE in Chinese tends to run a more benign course with fewer major organ involvement and fewer major relapses. The significantly higher incidence of male sex in late onset SLE and the milder disease course in the postmenopausal female patients suggest that oestrogen status may influence disease activity.