A new tool for predicting the probability of chronic kidney disease from a specific value of estimated GFR

Abstract

Objective. To demonstrate how patients’ probability of having chronic kidney disease (CKD) stage 3–5 (measured GFR <60 mL/min/1.73 m²) can be predicted from a specific value of estimated glomerular filtration rate (eGFR). Material and methods. The probability of CKD stage 3–5 was predicted from a logistic regression model (n = 850) using three different eGFR prediction equations: Lund-Malmö, MDRD and CKD-EPI. Population weighting was used to illustrate how this probability varies in three different populations: original sample (55% true prevalence of CKD stage 3–5), a screening (6.7% prevalence) and a CKD population (84% prevalence). Results. All three eGFR-equations had high classification ability (area under the receiver-operating-characteristic curve = 97%). The probability of CKD stage 3–5 increased with decreasing eGFR, varied substantially among the populations studied and to some extent between the eGFR-equations. Using the Lund-Malmö equation as illustration, the probability of CKD stage 3–5 is > 90% only when eGFR is <38 mL/min/1.73 m² in a screening population, whereas it is > 90% already when eGFR is <51 mL/min/1.73 m² in a CKD population. Conversely, the probability of CKD stage 3–5 is <10% if eGFR > 59 mL/min/1.73 m² in a screening population, whereas it is <10% only when eGFR is > 88 mL/min/1.73 m² in a CKD population. Conclusion. Instead of reporting diagnostic accuracy as sensitivity, specificity, and predictive values, actual eGFR supplemented with the probability that it represents a true GFR <60 mL/min/1.73 m² may be more valuable for physicians. Clinical (pre-test) probability in the population must be considered when predicting this probability.

Key Words::

• Kidney disease
• kidney function tests
• glomerular filtration rate
• renal insufficiency

Acknowledgements

The investigation was supported by grants from the Swedish Science Research Council (Project No. 5196) from the Alfred Österlund Foundation, Greta and Johan Kock Foundation, Medical Faculty of the University of Lund and from Region Skåne. We also thank Librarian Elisabeth Sassersson for excellent service regarding literature references.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.