In Lupus Nephritis, Research Uncovers Early Predictors of Stable, Long-Term Kidney Function

The combination of proteinuria and estimated glomerular filtration rate (eGFR) remains the best predictor of kidney outcomes, according to new data.

To evaluate laboratory parameters during the early course of lupus nephritis and their association with long-term stability of kidney function, the researchers enrolled 433 patients presenting at the National Institute of Medical Sciences and Nutrition Salvador Zubiran in Mexico City between 2008 and 2017. All patients had at least 36 months of follow-up and received a complete evaluation at their visit for a lupus nephritis flare, as well as 3, 6, and 12 months after the flare. The median follow-up period for the cohort was 73 months.

The evaluations included testing for albumin, anti-double-stranded DNA antibody (anti-dsDNA Ab), complement C3 and C4 fragments, creatinine, hemoglobin, and proteinuria over 24 hours. Each variable was evaluated individually and in association with other variables, and the change in area under the curve (AUC) was analyzed by using De Long’s test. The main outcome measure for the study was stable kidney function, defined as an eGFR within 25% of the best eGFR measured during the first 12 months of treatment of lupus nephritis.

The researchers found stable kidney function in 77% of the cohort after 3 years of follow-up and in 65% after 5 years. They also found that a level of proteinuria of less than 1.0 g/d at the 12-month follow-up evaluation was the best predictor of eGFR stability after 3 years of follow‑up and that the sum of proteinuria plus eGFR offered the best combined AUC at each timepoint in the study.

Proteinuria and eGFR AUCs improved at each timepoint until the 12-month follow‑up evaluation, and serum albumin and hemoglobin AUCs improved from baseline to the 3‑ and 6-month evaluations.  However, anti-dsDNA Ab and complement C3 and C4 levels did not improve from baseline values at any study timepoint.

The researchers noted that measurement of albumin, hemoglobin, and serological parameters during the early course of lupus nephritis did not improve the ability to predict long-term stable kidney function. “The combination of proteinuria and eGFR remains the best predictor of kidney outcomes,” they concluded.

—Ellen Kurek

Reference:

Mejia-Vilet JM, Gerrard MAN, Comunidad Bonilla RA, Morales-Buenrostro LE. Early predictors for stable kidney function in lupus nephritis. Paper presented at: American Society of Nephrology Kidney Week 2021; November 4-7, 2021; Virtual. https://www.asn-online.org/education/kidneyweek/2021/program-abstract.aspx?controlId=361248