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

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-Malmo (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-Malmo 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.