Specificity of the 2021 CKD-EPI Creatinine Equation
The provided evidence does not contain specificity values for the 2021 CKD-EPI creatinine equation.
What the Evidence Shows About Performance Metrics
The available guidelines and research studies report accuracy, bias, and precision metrics for the 2021 CKD-EPI equation, but do not provide traditional diagnostic test characteristics like specificity or sensitivity. 1
Performance Metrics Actually Reported
The evidence describes the 2021 CKD-EPI equation's performance using different measures:
Accuracy metrics (P30): The percentage of estimated GFR values falling within 30% of measured GFR, which ranges from approximately 80-90% depending on the population studied 2, 3
Bias: The 2021 CKD-EPI eGFRcr equation demonstrates minimal bias across GFR levels, with median bias ranging from -0.2 to 0.3 mL/min/1.73 m² in validation studies 2, 3
Precision: Interquartile ranges of approximately 14-15 mL/min/1.73 m² have been reported 2
Classification accuracy: The equation correctly classifies CKD stage in the majority of patients, though exact percentages vary by population 2, 4
Why Specificity Is Not Reported
Specificity is a diagnostic test characteristic that requires a binary outcome (disease present/absent) and a defined threshold. The 2021 CKD-EPI equation is a continuous estimating equation, not a diagnostic test with a single cutoff, which explains why traditional sensitivity and specificity values are not calculated or reported in the validation literature 1, 2, 3
Clinical Implications
The 2021 CKD-EPI equation is recommended for routine use based on its overall accuracy, minimal bias, and appropriate calibration across diverse populations, rather than on specificity values 1