Impact of Different CKD Definitions on Long-Term Renal Function and Mortality in a Population-Based Cohort Study

Abstract

Introduction: The adoption of age or individualized body surface area (i-BSA) estimated glomerular filtration rate (eGFR) thresholds could influence the prevalence and prognosis of chronic kidney disease (CKD). This longitudinal study with up to 15 years of follow-up in the general population, compares different eGFR thresholds for CKD definition: standard, corrected to i-BSA, and age-stratified. For each, we assessed the prevalence of CKD and the combined impact on rapid renal function decline (RRFD) and mortality. Methods: Patients were classified as CKD according to the presence of significant albuminuria and/or different eGFR thresholds as follows: (i) 65 years, respectively. We performed adjusted Cox regression analyses to predict RRFD and global mortality. Results: We analyzed 4952 participants (54% women; mean age: 52 years). Age-stratified definition resulted in 24 of 677 participants aged 65 years were reclassified as non-CKD, with 12 deaths and 1 RRFD. After multivariate adjustment, the CKD group had a poorer prognosis compared with the non-CKD group independently of the definition used; hazard ratio (HR) and 95% confidence interval (CI) were 2.23 (1.59–3.12), 2.06 (1.46–2.90), and 1.64 (1.13–2.38) for the standard, corrected to i-BSA, and age-stratified definitions, respectively. Conclusion: In our study, classification of CKD by age or i-BSA does not appear to improve prediction of RRFD and mortality.

Keywords

• age
• body surface area
• chronic kidney disease
• glomerular filtration rate
• mortality prognosis