[Comparison between two equations to estimated glomerular filtration rate].

BACKGROUND

There are several formulae to calculate estimated glomerular filtration rate (eGF). Two of those used most are MDRD study equation (Modification of Diet in Renal Disease) and the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI). On the contrary to the MDRD formula, the CKD-EPI equation included subjects with normal glomerular filtration rate. Our objective has been to compare the results obtained by both equations.

PATIENTS AND METHODS

FGE was calculated using the MDRD and CKD-EPI equation in 20000 subjects based on the data for gender, age and serum creatinine.

RESULTS

Mean age of patients was 73.5 ± 8.3 years. The eGF by the MDRD and CKD-EPI equations was 70.1 ± 29.0 and 68.1 ± 23.8 mL/min/1.73 m(2) (P<0.001, correlation coefficient: 0.926). For men, it was 71.3 ± 30.2 and 68.1 ± 24.2 mL/min/1.73 m(2) (P<0.001) and for women it was 69.0 ± 27.7 and 68.0 ± 23.3 mL/min/1.73 m(2) (P<0.001), respectively. In subjects ≥ 70 years, the eGF by MDRD was 3.1 mL/min/1.73 m(2), superior that by CKD-EPI (P<0.001). However, in patients <70 years, both equations had similar results. The prevalences of stages 1-2, 3, 4 and 5 for chronic renal disease were very similar (MDRD: 67, 25, 6 and 3%, and CKD-EPI: 68, 24, 6 and 3%). If the reference variable used the eGF by MDRD, the eGF by CKD-EPI reclassified 528 patients (2.6% of the total) into four stages of CKD (stage 1-2: 0.8%; stage 3: 7.5%; stage 4: 4.6% and stage 5: 0%).

CONCLUSIONS

The CKD-EPI equation applied to our population shows slightly lower levels than the MDRD. By stages, the new equation reduces the number of subjects in stage 3.