Late-onset systemic lupus erythematosus: Is it “mild lupus”?

Objective The objective of this paper is to investigate the clinical characteristics and prognosis of patients with late-onset systemic lupus erythematosus (SLE) using a prospective observational cohort. Methods Late-onset SLE (≥50 years old) was compared with adult-onset SLE (≥18 and <50 years old) using 1997 ACR classification criteria for SLE, autoantibodies, disease activity measured by Adjusted Mean SLE Disease Activity Index (AMS), and damage measured by Systemic Lupus International Collaborating Clinics/ACR Damage Index (SDI). The standardized mortality ratio (SMR) was calculated. Results A total of 917 patients with SLE were enrolled. The mean number of cumulative ACR criteria in late-onset SLE ( n = 32, 3.5%) was lower than that in adult-onset SLE (4.6 ± 1.2 vs. 5.5 ± 1.4, p < 0.05). The percentage of patients with low complement was lower in late-onset SLE than adult-onset SLE ( p < 0.05). AMS was also lower in late-onset SLE (2.7 ± 2.1 vs. 4.3 ± 2.6, p < 0.01), but SDI was similar between the two groups (50% vs. 43.4%, p = 0.58). The SMR of late-onset SLE was 1.58 (95% CI 0.58-3.43), while the SMR of adult-onset SLE was 3.34 (2.34-4.63). Conclusion Compared with adult-onset SLE, late-onset SLE has a lower number of ACR criteria and lower disease activity. Organ damage is not different, but prognosis and mortality are more favorable.