Creatinine- versus cystatin C-based renal function assessment in the Northern Manhattan Study

Abstract

Background

Accurate glomerular filtration rate estimation informs drug dosing and risk stratification. Body composition heterogeneity influences creatinine production and the precision of creatinine-based estimated glomerular filtration rate (eGFR _cr) in the elderly. We compared chronic kidney disease (CKD) categorization using eGFR _cr and cystatin C-based estimated GFR (eGFR _cys) in an elderly, racially/ethnically diverse cohort to determine their concordance.

Methods

The Northern Manhattan Study (NOMAS) is a predominantly elderly, multi-ethnic cohort with a primary aim to study cardiovascular disease epidemiology. We included participants with concurrently measured creatinine and cystatin C. eGFR _cr was calculated using the CKD-EPI 2009 equation. eGFR _cys was calculated using the CKD-EPI 2012 equation. Logistic regression was used to estimate odds ratios and 95% confidence intervals of factors associated with reclassification from eGFR _cr≥60ml/min/1.73m ² to eGFR _cys<60ml/min/1.73m ².

Results

Participants (n = 2988, mean age 69±10yrs) were predominantly Hispanic, female, and overweight/obese. eGFR _cys was lower than eGFR _cr by mean 23mL/min/1.73m ². 51% of participants’ CKD status was discordant, and only 28% maintained the same CKD stage by both measures. Most participants (78%) had eGFR _cr≥60mL/min/1.73m ²; among these, 64% had eGFR _cys<60mL/min/1.73m ². Among participants with eGFR _cr≥60mL/min/1.73m ², eGFR _cys-based reclassification was more likely in those with age >65 years, obesity, current smoking, white race, and female sex.

Conclusions

In a large, multiethnic, elderly cohort, we found a highly discrepant prevalence of CKD with eGFR _cys versus eGFR _cr. Determining the optimal method to estimate GFR in elderly populations needs urgent further study to improve risk stratification and drug dosing.