Background Systemic lupus erythematosus (SLE) is uncommon after the age of 50. The aim of this study was to determine clinical, biological and immunological characteristics of late-onset SLE.

Patients and methods We retrospectively analysed 246 files of SLE patients (ACR criteria). Two groups were defined according to age: late-onset SLE (age over 50 years) and adult-onset (between 18 and 50 years). Characteristics of SLE were compared in the two groups. P value was considered significant if <0.05.

Results Thirty four patients with late-onset SLE were studied; 29 women and five men. Adult-onset group included 173 women and 12 men (no difference in sex-ratio between the 2 groups). In late-onset SLE, mean age at disease onset was 56.9±6.4 years) and mean age at SLE diagnosis was 58±6.7 years. Mean delay from SLE onset to diagnosis was 18.64 months in late-onset group (similar to adult-onset SLE).

At time of SLE diagnosis, malar rash (25.8% vs 65.6%; p<0.0001) and Raynaud’s phenomenon (13% vs 35.5%; p=0.033) were significantly less frequent in late-onset group. Renal failure was more frequent in old patients (33.3% vs 10.5%, p=0.005) without difference in lupus nephritis frequencies.

During follow up, cutaneous manifestations (36.4 vs 82%; p<0.0001), lupus nephritis (25% vs 45.6%; p=0.03) were significantly less frequent in late-onset SLE.

Arthralgia was seen in 84.8% of patients (less frequent than adult-onset group without significant difference). Central neurologic involvements (18.2%), pericarditis (48.4%) and pleural effusion (33.3%) were more frequent in late-onset SLE without significant differences.

In late-onset SLE, anaemia was found in 67.5%, leucopenia in 40.6% and thrombocytopenia in 26.5% of patients (no differencies with adult-onset group).

Antinuclear antibodies were positive in all patients with late-onset disease and anti-DNA antibodies were positive in 69% of patients (similar to other group).

Anti-ENA antibodies were significantly less frequent in late-onset SLE (66.7% vs 87.5%, p=0.017).

Mortality rates was higher in older patients without statistical difference (20.9% vs 9%; p=0.14).

Conclusion Late onset SLE patients had less cutaneous manifestations and lupus nephritis but had higher rates of renal insufficiency and mortality; these can be related to co-morbidities.