Classification of chronic kidney disease in older Australian adults by the CKD-EPI 2009 and 2021 equations: secondary analysis of ASPREE study data.

OBJECTIVES

To assess the clinical impact on generally healthy older Australians of changing from the 2009 CKD-EPI (CKD-EPI) to the 2021 CKD-EPI (CKD-EPI) equation for calculating the estimated glomerular filtration rate (eGFR).

STUDY DESIGN

Secondary analysis of data from the prospective ASPirin in Reducing events in the Elderly (ASPREE) cohort study.

SETTING, PARTICIPANTS: Australians aged 70 years or older living in the community and without life-limiting medical conditions, recruited 1 March 2010 - 31 December 2014 for the ASPREE trial.

MAIN OUTCOME MEASURES

Baseline characteristics and long term health outcomes for participants classified to different chronic kidney disease (CKD) stages by CKD-EPI and CKD-EPI, and for those classified to the same CKD stage by both equations.

RESULTS

Complete data were available for 16 244 Australian ASPREE trial participants. At baseline, their mean age was 75.3 years (standard deviation, 4.4 years), and 8938 were women (55%); the median eGFR (CKD-EPI) was 74 mL/min/1.73 m (interquartile range [IQR], 64-85 mL/min/1.73 m), the median urine albumin-to-creatinine ratio 0.8 mg/mmol (IQR, 0.5-1.4 mg/mmol). eGFR values were higher for most participants with CKD-EPI than with CKD-EPI (median difference, 3.8 mL/min/1.73 m; IQR, 3.3-4.4 mL/min/1.73 m), and 3274 participants (20%) were classified to less advanced CKD stages by CKD-EPI. The proportion of participants with eGFR values below 60 mL/min/1.73 m (clinical CKD) was 17% (2770 participants) with CKD-EPI and 12% (1994 participants) with CKD-EPI. Participants were followed up at a median of 6.5 years (IQR, 5.4-7.9 years); the risks of reaching the disability-free survival composite endpoint (adjusted hazard ratio [aHR], 0.94; 95% confidence interval [CI], 0.84-1.05), all-cause mortality (aHR, 0.90; 95% CI, 0.78-1.03), major cardiac events (aHR, 0.94; 95% CI, 0.79-1.13), and hospitalisations with heart failure (aHR, 1.00; 95% CI, 0.67-1.49) were each similar for participants reclassified or not reclassified by CKD-EPI.

CONCLUSIONS

Using CKD-EPI would yield higher eGFR values than the CKD-EPI, substantially reducing the proportion of older Australian adults classified as having CKD, without any overall difference in long term health outcomes for people reclassified to less advanced CKD stages. Using the CKD-EPI could markedly reduce the number of referrals of generally healthy older adults to specialist nephrology services.