Cystatin C- and Creatinine-based Estimated GFR Differences: Prevalence and Predictors in the UK Biobank

Area of Science:

• Nephrology
• Clinical Chemistry
• Epidemiology

Background:

• Discrepancies between cystatin C-based (eGFRcys) and creatinine-based (eGFRcr) estimated glomerular filtration rates are frequent.
• Understanding factors contributing to these differences is crucial for accurate clinical interpretation.

Purpose of the Study:

• To comprehensively evaluate sociodemographic, lifestyle, comorbidity, and medication-related factors associated with significant eGFR differences.
• To develop and validate predictive models for identifying individuals with discrepant eGFR values.

Main Methods:

• A large cohort study of 468,969 participants from the UK Biobank.
• Multinomial logistic regression was used to identify predictors of lower eGFRcys or lower eGFRcr, developing clinical and enriched models.
• Models were validated internally on a subset of the data.

Main Results:

• 25% of participants had lower eGFRcys, and 5% had lower eGFRcr. Key predictors for lower eGFRcys included older age, male sex, South Asian ethnicity, smoking, thyroid dysfunction, inflammatory disease, steroid use, and obesity.
• Predictors for lower eGFRcr were largely inverse to those for lower eGFRcys.
• The enriched model achieved an AUC of 0.75 in the validation set with good calibration.

Conclusions:

• Numerous demographic, lifestyle, and health factors are linked to substantial eGFR differences.
• A clinical model can help identify individuals likely to have discrepant eGFRs, guiding the need for cystatin C testing.