Late-onset biopsy-proven lupus nephritis without other associated autoimmune diseases: severity and long-term outcome

Background/Purpose Lupus nephritis (LN) usually develops within the first years of systemic lupus erythematosus (SLE) onset and rarely after that. There are scarce studies comparing early- versus late-onset nephritis (before versus after five years of SLE diagnosis). The aim of this study was to compare the severity and long-term outcome (after 7 years) in these two, late-onset and early-onset, nephritis groups. Methods This study included 93 patients from rheumatology tertiary centers from Brazil and Italy, all of them with biopsy-proven LN with > 7 years follow-up. Patients were divided in two groups: early-onset nephritis (n = 75) and late-onset nephritis (n = 18). Clinical and laboratorial data were obtained using a standardized electronic chart database protocol carried out at 1-6 months interval and established in 2000. Patients >50 years or with concomitant autoimmune diseases were excluded. Variables evaluated at the LN presentation were Systemic Lupus Erythematosus Disease Activity Index (SLEDAI), creatinine, albumin, anti-DNA positivity and nephritis class. Variables evaluated at the long-term outcome (after 7 years) were Systemic Lupus International Collaborating Clinics Damage Index (SDI), creatinine, dialysis and mortality. Results The average time of LN presentation was 10.94 +/- 3.73 years for the late-onset and 1.20 +/- 1.60 years for the early-onset group. Their similar nephritis duration (12.44 +/- 3.2 versus 13.28 +/- 4.03 years, p = 0.41) and comparable mean ages (49.17 +/- 9.9 versus 44.11 +/- 10.8 years old, p = 0.06) allow a more accurate comparison. Regarding severity, late-onset was similar to early-onset group: SLEDAI (8 (range: 6-22) versus 12 (range: 2-24), p = 0.47), creatinine (1.36 +/- 0.94 versus 1.36 +/- 1.13 mg/dl, p = 0.99); albumin (2.84 +/- 0.65 versus 2.59 +/- 0.84 mg/dl, p = 0.30); proteinuria (3.77 +/- 2.18 versus 5.01 +/- 4.51 g/vol, p = 0.26); proliferative nephritis (44% (n = 8) versus 60% (n = 45), p = 0.23). There was also no difference in the long-term outcomes between groups: SDI (1 (range: 0-5) versus 0.5 (range: 0-5), p = 0.27); creatinine (2.04 +/- 2.38 versus 1.69 +/- 2.26 mg/dl, p = 0.56); dialysis (22% (n = 4) versus 13% (n = 10), p = 0.46) and mortality (0% (n = 0) versus 12% (n = 9), p = 0.19). Conclusion This study provides novel evidence of comparable long-term outcomes between late-onset and early-onset nephritis, which is most likely explained by the observation that at presentation, the clinical, laboratorial and histological features of late-onset and early-onset nephritis are similar. This suggests that there should be no distinct treatment targets and therapeutic interventions for the late- and early-onset groups.