Chapter 5 CKD, eGFR, proteinuria

5.1 eGFR

CKD-EPI (2012): - comparison of CKD-EPI and MDRD in a meta-analysis of data from over 1 million adults followed for a median of over 7 years. CKD-EPI classified fewer individuals as having CKD and was more tightly associated with risk of mortality and ESRF.

(An evidence-based argument for age-specific eGFR thresholds for defining CKD was presented in 2019.)

5.2 Association of eGFR and proteinuria with hard outcomes

Alberta cohort (2006): - large cohort study in general population in Canada. Adjusted rates of mortality, MI and CKD progression were all higher with increasing albuminuria.

CKD prognosis consortium (2010): - large cohort study in general and high-CVS risk populations. Increasing eGFR and ACR associated with higher rates of all-cause and cardiovascular mortality and of ESRF.

5.3 Estimating risk of CKD progression

The 4-variable and 8-variable kidney failure risk equations have been used to predict risk of ESKD in CKD. The 4vKFRE has age, sex, eGFR and uACR as inputs.

The 4vKFRE provides an accurate estimate of 2- and 5-yr risk of ESKD in a range of kidney diseases.

Hundemer et al. (2020): - retrospective cohort study of 1200 patients with CKD in Canada. AUC >0.8 on ROC curves; Brier scores ~0.17 for both 2- and 5- yrs.

The KFRE is better than patients or physicians at predicting progression to ESKD.

Potok et al. (2019): - relative performance of 4vKRFE, patients’ estimate and physicians’ estimate of 2 yr ESKD risk. Single-centre in California. 4vKRFE was best calibrated with actual incidence of ESKD; both physicians and patients tended to over-estimate risk.

5.4 Competing risk of death

O’Hare et al (2007): - cohort of 200,000 US veterans with CKD3–5. Defined risk of death and ESRF according to age and GFR. GFR at which risk of ESRF exceeds risk of death was ~45 ml/min at age 30, ~30 ml/min at age 50 and ~15 ml/min at age 70.

Ravani et al (2020): - cohort study of ~30,000 adults with CKD IV in Canada. Risk of ESKD was higher than risk of death if aged < 65. Between 65 and 75 years, risks of ESKD and mortality were similar. Above this age, risk of death out-competed risk of ESKD. Relative risk of mortality (comparted to ESKD) was 6x if aged over 75 and 25x if aged over 85.