Evaluation of the CKD-EPI 2021 creatinine equation using laboratory data: Considerations for practice changes among clinical laboratories in British Columbia, Canada

Introduction: Clinical laboratories in British Columbia, Canada implemented the CKD-EPI 2009 equation without the race variable for estimated glomerular filtration rate (eGFR) reporting since 2014. As more clinical laboratories adopt the new CKD-EPI 2021 equation, the study aims to compare these two race-free CKD-EPI eGFR equations using the laboratory data from a large tertiary hospital in BC and evaluate the impact on reclassification of eGFR category.

Methods: Serum/plasma creatinine results and demographic data were collected from Vancouver General Hospital laboratory. The CKD-EPI 2009 without the race variable and CKD-EPI 2021 equations were computed. eGFR and its distributions were compared and reclassification of eGFR category was assessed across the full cohort and in specific patient populations.

Results: The analysis included 58,763 patients. The median age was 57 years, with women comprising 51 % of the population. The median of eGFR changed from 85 to 90 mL/min/1.73 m² using the CKD-EPI 2009 equation without the race variable and the CKD-EPI 2021 equation, respectively. The CKD-EPI 2021 equation reclassified 11.86 % of patients, mainly from G3a (45-59 mL/min/1.73 m²) to G2 (60-89 mL/min/1.73 m²). There was statistical significance between the non-renal and the renal population reclassified from G5 (<15 mL/min/1.73 m²) to G4 (15-29 mL/min/1.73 m²).

Conclusions: Using laboratory data representative of local populations, we observed an overall positive shift to higher eGFR, with 11.86 % of individuals having improved eGFR categories based on the CKD-EPI 2021 equation. This study provides insights into clinical implications at both the individual and population levels. The data-based approach is the first step towards adopting the CKD-EPI 2021 equation within the province.