Urinary protein reduction in patients with focal segmental glomerulosclerosis (FSGS) is associated with improvement in kidney function and a reduced risk for end-stage kidney disease (ESKD), new data suggest.
In an analysis of 138 patients with steroid-resistant primary FSGS who participated in a multicenter randomized trial comparing treatment with cyclosporine and mycophenolate mofetil, investigators found that changes in proteinuria over 26 weeks were significantly related to estimated glomerular filtration rate (eGFR) slope. Each 1-unit decrease in log-transformed urinary protein-creatinine ratio (UPCR) was associated with a 3.90 mL per year rise in eGFR. The association remained significant after adjusting for complete remission. In addition, each 1-unit reduction in log-transformed UPCR was significantly associated with a 77% decreased risk for ESKD, Jonathan P. Troost, PhD, of the Michigan Institute for Clinical and Health Research at the University of Michigan in Ann Arbor, and colleagues reported in the American Journal of Kidney Diseases.
“These novel findings expand on previous reports showing that complete and partial proteinuria remissions are associated with large clinical benefit, and also suggest that reduction in proteinuria — even if not to a complete remission — is still associated with improved survival,” Dr Troost and colleagues wrote.
In addition, the study provides estimated effect sizes on eGFR preservation and survival at various levels of proteinuria reduction for different lengths of follow-up, the authors stated. “These can aid in delineating prognosis, assessing the impact of treatment, clinical decision making, and in the design of clinical trials,” they said.
Study findings suggest that the efficacy of FSGS treatments may be gauged based on the continuous decrease in proteinuria as well as predefined cut-off values, Dr Troost’s team wrote.
The study was limited by its relatively modest sample size and enrollment restricted to patients with steroid-resistant FSGS, according to the authors. Another limitation was the lack of follow-up beyond 5 years. “Thus, we cannot be certain that the benefit of graded reductions in proteinuria is sustained.”
Troost JP, Trachtman H, Spino C, et al. Proteinuria reduction and kidney survival in focal segmental glomerulosclerosis. Am J Kidney Dis. Published online August 10, 2020. doi:10.1053/j.ajkd.2020.04.014