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Abstract
Objectives To assess the minimum effective duration of clinical remission capable of protecting against damage accrual and development of impaired kidney function (IKF) in lupus nephritis (LN)
Methods Patients with biopsy-proven LN and at least 5 years follow-up were enrolled in this study. Sustained Clinical remission (sCR) (henceforth: remission) was defined as eGFR>60 ml/min/1.73m2, proteinuria <0.5g/24h and clinical SLE-disease activity index (cSLEDAI)=0 lasting for at least one year. The duration of remission to prevent IKF (eGFR <60 ml/min per 1.73 m2 (32) for at least 3 months) was estimated through Kaplan-Meier curves and compared by log-rank. Spearman correlation analysis was performed to assess the potential correlation between the yearly increase in SLICC damage index (SD) and the percentage of follow-up spent in remission.
Results 303 LN patients were included (median follow-up: 14.8 (9.8–22) years) of whom 84.8% achieved sCR lasting 8.6±6.9 years. At the last observation, the increase in SDI from baseline was significantly higher in patients who never achieved vs. those who achieved remission (median: 2 (1–3) vs. 1 (0–1), p=0.003). Consistently, the higher the percentage of follow-up spent in remission, the lower the yearly SDI increase (r=-0.3285, p<0.00001), figure 1. Two-hundred-twenty-five patients had ≥10 years of observation. Among them, 127 were in remission at last observation. Of the remaining 98 patients, 49 (50%) developed IKF. We found that at least 3 years of remission significantly differentiated patients who developed IKF from those who did not: the IKF-free survival at 10 and at 20 years were 93% and 79% in patients with at least 3 years remission in comparison to 67% and 40% in those with less than 3 years of remission (p<0.0001), figure 2.
Conclusions Three years was the minimum duration of sustained remission capable of protecting against development of IKF in patients with LN. Remission protects from overall damage, and the longer the remission the lower the SDI increase.
Spearman correlation between yearly SDI values and the percent of follow-up in clinical remission for each patient
CKD free survival curves in patients with at least 3 years of clinical remission and in those with less than 3 years of complete remission
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