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 m(2) 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 m(2)) constituted the Lund-Malmö Study cohort. Bias, precision, accuracy, expressed as median absolute percentage difference and percentage of estimates ±10% (P(10)) and ±30% (P(30)) 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 m(2). 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 m(2) 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 m(2). However, the LM equations cannot be recommended for use in general clinical practice until validated in other populations.