Comparison of complete renal response and mortality in early- and late-onset lupus nephritis: a multicenter retrospective study of a Japanese cohort

Most patients with systemic lupus erythematosus (SLE) progress to lupus nephritis (LN) within 5 years of their SLE diagnosis, although it is not uncommon for LN to develop at later time points. Here we evaluated the clinical features of early- and late-onset LN. We retrospectively analyzed the cases of 184 of the 201 patients who underwent a renal biopsy at Nagasaki University Hospital and associated community hospitals between 1990 and 2016 and were diagnosed as having LN. Early onset was defined as the development of LN within the first 5 years after the patient's SLE diagnosis, and late onset was defined as LN development > 5 years post-diagnosis. We analyzed the complete renal response (CR) at 6 and 12 months after induction therapy, the classification of renal pathology, and the mortality of the early- and late-onset LN groups. The mean follow-up duration after the renal biopsy was 123 ± 85 months. There were 113 (61.4%) early-onset patients and 71 (38.6%) late-onset patients. A multivariate analysis revealed that the following factors were predictive of CR: at 6 months: female sex (odds ratio [OR] 3.93, 95% confidence interval [CI] 1.31-11.77, p = 0.010), proteinuria (OR 0.83, 95% CI 0.71-0.97, p = 0.009), index of activity (0-24) (OR 0.83, 95% CI 0.70-0.99, p = 0.030), and early-onset LN (OR 2.39, 95% CI 1.15-4.98, p = 0.018); at 12 months: female sex (OR 3.60, 95% CI 1.32-9.83, p = 0.013), mixed LN (OR 0.18, 95% CI 0.04-0.80, p = 0.024), index of activity (0-24) (OR 0.80, 95% CI 0.68-0.94, p = 0.007), and early-onset LN (OR 2.10, 95% CI 1.05-4.23, p = 0.035). In a Cox proportional hazards and Fine-Gray regression model, the early-onset LN group had a significantly better mortality rate than the late-onset LN group (p = 0.038 and p = 0.043, respectively). In our cohort, early-onset LN was a better predictor of CR at 6 and 12 months than late-onset LN. Our results suggest that early-onset LN patients had lower mortality than late-onset LN patients.