Worse renal presentation and prognosis in initial-onset lupus nephritis than early-onset lupus nephritis

Purpose: To compare the clinical characteristics and renal outcomes between patients who initially had lupus nephritis (LN) at the onset of systemic lupus erythematosus (SLE) (initial-onset LN) and those who developed LN within 5 years after SLE onset (early-onset LN). Materials and Methods: SLE patients with biopsy-proven LN were retrospectively reviewed. The clinical parameters and renal outcomes were compared between initial-onset and early-onset LN groups. We used Cox regression analysis to estimate risk of worse renal outcomes according to the onset time of LN. Results: Of all 136 LN patients, 92 (67.6%) and 44 (32.4%) patients were classified into the initial-onset and early-onset LN groups, respectively. The initial-onset LN group had higher prevalences of class IV LN (54.3% vs. 34.1%, p=0.027), impaired renal function (34.8% vs. 11.4%, p=0.004), microscopic hematuria (73.9% vs. 54.5%, p=0.024), and higher urine protein/creatinine ratio [4626.1 (2180.0–6788.3) mg/g vs. 2410.0 (1265.0–5168.5) mg/g, p=0.006] at LN diagnosis. Renal relapse (46.3% vs. 25.7%, p=0.039) and progression to chronic kidney disease (CKD) or end-stage renal disease (ESRD) were more common (24.4% vs. 8.3%, p=0.042) in the initial-onset LN group. In Cox regression analysis, the initial-onset LN group had higher risks of renal relapse [adjusted hazard ratio (HR) 3.56, 95% confidence interval (CI) 1.51–8.35, p=0.004] and progression to CKD or ESRD (adjusted HR 4.57, 95% CI 1.03–20.17, p=0.045), compared with the early-onset LN group. Conclusion: Patients with LN at SLE onset may have more severe renal presentations and experience worse renal outcomes than those who develop LN within 5 years.