Background/Purpose: Early endpoints predicting long-term outcome in lupus nephritis (LN), which could be used as outcome measures in clinical trials, are still debated. Recently, a multicentric study, using an extended international database of prospectively followed LN patients, succeeded in computing equations (hazard index; HI) predicting adverse kidney outcomes, in casu chronic kidney disease (CKD), severe kidney injury (SKI) and renal replacement therapy (RRT). These HI were validated in a replicate cohort. The HI for CKD, SKI and RRT (calculated with data measured at one year) were significantly higher in groups with long-term poor renal outcomes after a follow-up (FU) of ≥ 4 years (Mackay M et al. Arthritis Rheumatol 2016; 68 (suppl.10), abstract 967).

Objectives: To validate the HI for CKD, SKI and RRT in an independent LN cohort followed for ≥ 4 years and to check their validity to predict outcome in patients followed for ≥ 9 years.

Methods: Data from 229 consecutive LN patients followed in a single lupus center were screened. Only those for whom clinical data were available following their first episode of proliferative and/or membranous biopsy-confirmed LN were selected. Serum creatinine and proteinuria at different time points from 102 LN patients followed for ≥ 4 years were analyzed. At last FU, patients were divided according to the presence or absence of CKD, SKI and RRT. Their respective HI, measured at one year, were compared. CKD/SKI were defined as ≥ 30%/≥ 50% decrease in eGFR (CKD-EPI equation), compared to the highest value measured within the first year.

Results: As illustrated in the Table, the mean HI for CKD and SKI, measured at one year, were significantly higher in the groups of patients who indeed developed CKD and SKI after a FU of ≥ 4 years compared to those who did not. Importantly, the HI predictive value remained valid after a FU of ≥ 9 years. The mean HI for RRT was higher in patients who developed RRT after ≥ 4 and ≥ 9 years, but the difference was not statistically significant (p=0.08 and p=0.25, respectively), most likely due to the small numbers of RRT in this series. Of note, clinical (gender, age, mean serum creatinine, mean proteinuria) and pathological (ISN/RPS class) characteristics did not differ at baseline between patients with poor long-term renal outcome compared to the others.

Conclusion: We confirm the validity of the HI equations as early predictors of poor renal outcomes (CKD and SKI after long-term FU). These HI tools could be used as outcome measures in LN clinical trials.

HI : hazard index; figures between brackets correspond to numbers of patients; CKD : chronic kidney disease; SKI : severe kidney injury; RRT : renal replacement therapy; ^*: p<0.005; ^**: p<0.05 (Mann-Whitney U-tests).

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/early-prediction-of-long-term-renal-outcomes-in-lupus-nephritis-using-hazard-index-equations/