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The following is a summary of “Comparative CKD risk prediction using homocitrulline and carbamylated albumin: two circulating markers of protein carbamylation,” published in the May 2024 issue of Nephrology by Awwad et al.

Protein carbamylation, driven by urea, is linked to adverse outcomes in chronic kidney disease (CKD). Biomarkers like carbamylated albumin (C-Alb) and homocitrulline (HCit, carbamylated lysine) measure carbamylation burden, but their comparative prognostic value is unclear.

Researchers conducted a prospective study comparing C-Alb and HCit’s prognostic usefulness to aid future carbamylation studies and facilitate comparisons between existing ones. 

They measured serum C-Alb and free HCIT in 1632 CKD stage 2-4 patients from the Chronic Renal Insufficiency Cohort (CRIC) study. Adjusted Cox proportional hazard models primarily evaluated mortality and end-stage kidney disease (ESKD) risks for each marker. Later, C-statistics and other metrics were used to compare the prognostic value of each marker. 

The results showed that participants included were mean (SD) 59 (11) years old, 702 (43%) females, and 700 (43%) white. The C-Alb and HCit levels correlated positively (Pearson correlation coefficient 0.64). Both showed a similar increased risk of death (HR for death in the 4th carbamylation quartile compared to 1st was 1.90 [1.35-2.66] for C-Alb and 1.89 [1.27-2.81] for HCit). Similar findings were found for ESKD risk. The C-statistics and other metrics showed comparable prognostic value. With both C-Alb and HCit, the C-statistics showed a mortality rate of 0.725 [0.707-0.743], compared to a base model 0.723. The net reclassification improvement and integrated discrimination improvement metrics were also similar. 

Investigators concluded that C-Alb and HCit performed similarly predicting outcomes, suggesting that CKD studies were easily comparable.

Source: bmcnephrol.biomedcentral.com/articles/10.1186/s12882-024-03619-6