Comparison of Clinical Features, Treatment and Outcomes of Lupus Nephritis Between Patients With Late- and Early-Onset Systemic Lupus Erythematosus: A Controlled Study.

Background: Studies have found that late-onset systemic lupus erythematosus (SLE) patients (age at diagnosis ≥ 50 years) had less severe disease and milder clinical course, but with higher organ damage and mortality rate than early-onset ones (age at diagnosis < 50 years). Unfortunately, direct comparison of renal manifestations and treatment outcomes between late- and early-onset SLE patients has been determined rarely. This study aimed to compare lupus nephritis (LN) manifestations, treatment, and outcomes between late- and early-onset in SLE patients. Methods: Medical records of SLE patients in a lupus cohort at a tertiary care university hospital, seen between January 1994 and June 2020, were reviewed. Late- and early-onset patients were matched with year at SLE diagnosis at a ratio of 1:2 (62 and 124 patients, respectively). Those with LN were identified and analyzed. Results: At SLE onset and end of the study, LN was identified in 29 and 33 late-onset patients, respectively, and 58 and 90 early-onset patients, respectively. At the end of the study, there were 39 and 214 LN flares in late- and early-onset patients, respectively: giving an incident rate (IR) (95% confidence interval (CI))/100 person-years of LN and active LN flares of 2.00 (0.75 - 5.33) vs. 6.11 (4.32 - 8.64), P = 0.020, and 5.78 (2.75 - 12.12) vs. 18.28 (13.93 - 24.00), P = 0.001, respectively. Late-onset patients received a higher proportion of moderate- to high-dose corticosteroids, but fewer immunosuppressive drugs. In all LN flares, no difference existed between the two groups in serum creatinine, degree of proteinuria, and proportion of patients with nephrotic range proteinuria or rapidly progressive glomerulonephritis, and outcomes in terms of complete, partial or no-remission were similar between them. Mortality rate was higher in late-onset patients (27.27% vs. 6.67%, P = 0.004). Conclusion: This matched controlled study of year at SLE diagnosis showed that late-onset SLE patients had lower prevalence of LN and LN flares. Although they received fewer immunosuppressive drugs, their renal manifestations and treatment outcomes were no different from those in early-onset patients.