A study shows that sustained proteinuria is a strong predictor for the rate of progression of renal disease, and proteinuria yields better outcomes in primary IgA nephropathy (IgAN). The results were published in the Journal of The American Society of Nephrology.
“Many studies have shown that proteinuria is a predictor of outcome in IgAN. Experimental evidence supports these human data by clarifying the direct deleterious effect of proteinuria on renal tissue,” the researchers wrote.
In this analysis, researchers gleaned patient data from the Toronto Glomerulonephritis Registry, which consists of biopsy-proven cases of GN from the greater Toronto area. Overall, 1,373 patients with confirmed IgAN were included in the study. Exclusion criteria was defined as any patients with incomplete clinical data, patients younger than 16 at presentation, those with less than 12 months of follow-up, or patients with a secondary case of IgA deposition. In total, 542 patients were included for analysis. Patient age, ethnicity, gender, and body mass index were recorded at the first indication of GN. The researchers prospectively analyzed weight, blood pressure, medication exposure, and laboratory parameters, including creatine, albumin, urinalysis results, and 24-hour urine protein and creatine excretion.
According to the results, glomerular filtration rate (GFR) declined overall, with 30% of patients reaching end-stage renal disease. The results of multivariate analysis demonstrated that proteinuria during follow-up was the most salient predictor of the rate of GFR decline. Specifically, among 171 patients with < 1 g/d of sustained proteinuria, the rate of decline was 90% slower than the mean rate. Patients who presented with ≥ 3 g/d who achieved a partial remission displayed a similar course to patients who had ≤ 1 g/d throughout and fared far better than patients who never achieved remission. “These results underscore the relationship between proteinuria and prognosis in IgA nephropathy and establish the importance of remission,” the researchers wrote.
The researchers noted that this analysis was never intended to assess the benefit of any therapeutic interventions for IgAN. “The most important conclusion derived is that the reduction of proteinuria by whatever means (medication, MAP reduction) is of great clinical benefit,” they wrote.