Revised equations for estimating glomerular filtration rate based on the Lund-Malmö Study cohort

Abstract

Objective. To increase the accuracy of estimated GFR (eGFR) from creatinine overall and at measured GFR ≥90 mL/min per 1.73 m² by revising the Lund-Malmö (LM) equations, to elaborate on more complex forms to improve the LM and CKD-EPI equations further, and to assess benefits of adding lean body mass (LBM). Material and methods. Swedish Caucasians (n = 850, 376 women; median 60, range 18–95 years) referred for GFR measurement (plasma iohexol-clearance: median 55, range 5–173 mL/min/1.73 m²) constituted the Lund-Malmö Study cohort. Bias, precision, accuracy, expressed as median absolute percentage difference and percentage of estimates ±10% (P₁₀) and ±30% (P₃₀) of measured GFR, and classification ability with respect to five GFR stages were compared with the original LM, CKD-EPI and MDRD equations. Results. LM Revised overall performed better than LM Original without LBM due to increased accuracy at measured GFR ≥90 mL/min/1.73 m². Further extensions of the CKD-EPI or LM equations did not substantially improve overall performance. In particular, the performance of LM Revised at measured GFR ≥90 mL/min/1.73 m² could not be improved further without decreasing accuracy and classification ability at lower GFR-levels. Adding LBM to the equations had no strong effect on accuracy. Conclusion. Comparisons with the CKD-EPI and MDRD equations suggest that the LM equations are superior for the present Swedish population, due to markedly higher accuracy of the LM equations at measured GFR <30 mL/min/1.73 m². However, the LM equations cannot be recommended for use in general clinical practice until validated in other populations.

Key Words::

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

Acknowledgement

We thank librarian Elisabeth Sassersson for her 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.