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

摘要

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.