New research indicates that low-grade proteinuria in lupus nephritis patients does not signal improved renal outcomes or treatment responses, while glomerulosclerosis is linked to kidney function decline in those who experience disease relapse.
The study, led by Nan Shen, MD, PhD, a professor of medicine at Shanghai JiaoTong University, examined clinical characteristics, renal pathology, treatment responses, and long-term kidney outcomes in patients with varying baseline proteinuria levels.
Previous research suggested that proteinuria is the strongest predictor of long-term renal outcomes in lupus nephritis, outperforming serum creatinine and urinary red blood cells. However, it remained unclear whether patients with low-grade proteinuria at baseline enjoy better clinical or histologic outcomes over time.
In lupus nephritis research, a 30–40% decline in estimated glomerular filtration rate (eGFR) over several years is often used as a surrogate marker for progressive kidney function loss. In contrast, glomerulosclerosis, assessed via biopsy, reflects chronic structural scarring. By analyzing both functional decline and structural damage, researchers aimed to determine whether baseline proteinuria or chronicity features predict long-term renal outcomes.
The longitudinal cohort study included 239 patients with biopsy-proven lupus nephritis. Patients were stratified by baseline proteinuria—low-grade (<1 g/24 h; n = 42) versus high-grade (≥1 g/24 h; n = 197)—and by disease onset: incident or relapsing. Treatment responses were assessed at weeks 26 and 52, while long-term kidney function, measured by 30% and 40% eGFR decline, was evaluated up to 156 weeks using Cox regression and Kaplan–Meier analyses.
Results showed that patients with low-grade proteinuria had fewer urinary sediments, more frequent class V pathology, and a lower renal activity index compared with those with high-grade proteinuria. However, chronicity index and overall remission rates at weeks 26 and 52 were similar across groups.
By week 156, the risk of 30% or 40% eGFR decline was comparable between low- and high-grade proteinuria groups. Notably, glomerulosclerosis independently predicted long-term kidney deterioration in patients with relapsing lupus nephritis but not in those with incident disease.
“These findings highlight the importance of early biopsy, personalized treatment, and close monitoring, supported by non-invasive biomarkers for risk assessment,” the investigators concluded.
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