Measuring albuminuria better than estimation in predicting kidney failure risk

Although both albuminuria and proteinuria are effective in predicting the risk of kidney failure with replacement therapy (KFRT) in chronic kidney disease (CKD) patients, measuring albuminuria (mACR) is preferred over estimating it (eACR), especially in cases of low albuminuria levels, according to a study.

The study included 2099 patients diagnosed with CKD grades 1-5, who did not require kidney replacement therapy. Researchers measured spot urine albumin-to-creatinine ratio (mACR) and protein-to-creatinine ratio (PCR), and estimated ACR (eACR) using PCR. Kidney Failure Risk Equation (KFRE) scores were calculated based on these measurements. The primary outcome assessed was the 5-year risk of kidney failure with replacement therapy (KFRT).

Results indicated that eACR consistently underestimated mACR levels, particularly in patients with low albuminuria. The time-dependent area under the receiver operating curve demonstrated strong predictive performance for all KFRE scores derived from mACR, PCR, and eACR. However, when examining the continuous net reclassification index (cNRI) and integrated discrimination improvement index (IDI), eACR consistently lagged behind mACR across all CKD cause groups, except for cases with unclassified etiology.

The statistics derived from cNRI and IDI indicated that both eACR and PCR were less effective than mACR in patients exhibiting low levels of albuminuria (less than 30 mg/g). Conversely, PCR demonstrated superior predictive performance in cases of severe albuminuria and nephrotic-range proteinuria. In these instances, the IDI and cNRI values for PCR were higher than those for mACR.

Reference
Kim H, Hyun YY, Joo YS, et al; KNOW-CKD investigators. Proteinuria, measured or estimated albuminuria for risk prediction in patients with chronic kidney disease? Nephrol Dial Transplant. 2023;gfad195. doi: 10.1093/ndt/gfad195. Epub ahead of print. PMID: 37723608.