Applicability of a different estimation equation of glomerular filtration rate in Turkey

Figures & data

Table 1. GFR prediction equations based on serum creatinine level.

Formulae	Equations
Cockroft-Gault (creatinine clearance measurement, mL/min)	(140 − age) × weight (kg)/72 × Scr ( × 0.85 if female)
MDRD 1 (GFR measurement, mL/min per 1.73 m^2)	170 × × age^−0.176× (0.762 if female) × (1.180 if black) × serum urea (mg/dL)^−0.170× serum albumin (g/dL)^+0.318
MDRD 2 (GFR measurement, mL/min per 1.73 m^2)	186 × × age^−0.203× (1.212 if black) × (0.742 if female)
IDMS-traceable MDRD (GFR measurement, mL/min per 1.73 m^2)	175 × (†Scr)^−1.154× (age)^−0.203× (0.742 if female) × (1.212 if African American) 15
Jelliffe 1 (creatinine clearance measurement, mL/min per 1.73 m^2)	98 − 0.8 × (age − 20)/Scr ( × 0.90 if female)
Jelliffe 2 (creatinine clearance measurement, mL/min)	Male: 100/Scr − 12, Female: 80/Scr − 7
Mawer (creatinine clearance measurement, mL/min)	Male: weight × [29.3 − (0.203 × age)] × [1 − (0.03 × Scr)]/(14.4 × Scr) ×(70/weight), Female: weight × [25.3 − (0.175 × age)] × [1 − (0.03 × Scr)]/(14.4 × Scr) × (70/weight)
Bjornsson (creatinine clearance measurement, mL/min)	Male: [27 − (0.173 × age)] × weight × 0.07/Scr, Female: [25 − (0.175 × age)] × weight × 0.07/Scr
Gates (creatinine clearance measurement, mL/min)	Male: (89.4 × ) + (55 − age) × (0.447 × ), Female: (60 × ) + (56 − age) × (0.3 × )
Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI)(GFR measurement, mL/min per 1.73 m^2)	141 × min (†Scr/κ, 1)^α× max (†Scr/κ, 1)^−1.209× 0.993 age × 1.018 [if female] × 1.159 [if black]κ is 0.7 for females and 0.9 for males, α is −0.329 for females and −0.411 for males. Min indicates the minimum †Scr/κ or 1, and max indicates the maximum of †Scr/κ or 1.8

S_cr: serum creatinine, MDRD 1: Modification of Diet in Renal Disease 1 (for six variables), MDRD 2: Modification of Diet in Renal Disease 2 (for four variables), GFR: Glomerular filtration rate, IDMS: Isotope dilution mass spectrometry, †Isotope dilution mass spectrometry traceable creatinine was used.

Table 2. Clinical and laboratory characteristics of study subjects.

Characteristics	n = 229
Age (years)	53.92 ± 14.96
Sex (Male/Female)	113/116
Weight (kg)	72.92 ± 13.50
Height (cm)	162.3 ± 9.99
Body surface area (m^2)	1.78 ± 0.18
Body mass index (kg/m^2)	27.8 ± 5.3
Serum urea (mg/dL)	67.97 ± 38.63
Serum creatinine (mg/dL)	1.93 ± 1.14
IDMS-traceable serum creatinine (mg/dL)	1.78 ± 1.15
Serum albumin (g/dL)	3.84 ± 0.65

IDMS: Isotope dilution mass spectrometry.

Table 3. Mean measured (iohexol) and estimated glomerular filtration rate values.

Formulae	mL/min
Iohexol GFR	47.24 ± 34.05
Cockroft-Gault	64.07 ± 43.29
Jelliffe 2	61.04 ± 40.20
Mawer	70.86 ± 54.45
Bjornsson	67.54 ± 45.25
Gates	57.73 ± 39.60
	mL/min/1.73m2
Iohexol GFR	45.60 ± 32.17
MDRD 1 (six variables)	47.83 ± 33.58
MDRD 2 (four variables)	47.36 ± 28.35
IDMS-traceable MDRD†	56.69 ± 39.03
Jelliffe 1	54.42 ± 36.56
CKD-EPI	54.58 ± 34.59

GFR: Glomerular filtration rate, MDRD: Modification of Diet in Renal Disease, IDMS: Isotope dilution mass spectrometry, CKD-EPI: Chronic Kidney Disease Epidemiology Collaboration

†Isotope dilution mass spectrometry traceable creatinine was used.

Table 4. The bias, random error, precision lower and upper agreement limits and accuracies of the estimation equations.

					Accuracy (% within specified range of iohexol GFR)
Estimation equations	Bias	Random error	Precision lower agreement limit (95% Cl)	Precision upper agreement limit (95% Cl)	±15%	±30%
Cockroft-Gault (mL/min)	17.16 ± 14.70	18.22	−19.69	54.01	21.5	39.5
MDRD 1 (mL/min per1.73 m^2)	2.47 ± 0.51	10.15	−26.95	31.89	39.8	69.9
MDRD 2 (mL/min per 1.73 m^2)	1.94 ± 0.03	10.21	−26.75	30.63	42.9	69.9
IDMS-traceable MDRD† (mL/min per 1.73 m^2)	11.33 ± 8.97	14.21	−23.87	46.53	34.1	54.9
Jelliffe 1 (mL/min per 1.73 m^2)	8.74 ± 6.73	12.80	−21.29	38.77	28.8	56.6
Jelliffe 2 (mL/min)	13.80 ± 11.06	18.05	−27.48	55.08	23.1	41.9
Mawer (mL/min)	23.95 ± 19.94	25.07	−36.16	84.06	20.6	36.8
Bjornsson (mL/min)	20.63 ± 17.99	21.21	−18.96	60.22	18.0	31.6
Gates (mL/min)	10.49 ± 7.86	14.98	−29.12	50.10	31.0	52.4
CKD-EPI (mL/min per 1.73 m^2)	8.90 ± 7.03	12.21	−19.11	36.91	34.5	56.6
Corrected MDRD - GFR (mL/min per 1.73 m^2)	0.17 ± 14.87	9.81	−28.98	29.32	41.2	74.3

GFR: Glomerular filtration rate, MDRD 1: Modification of Diet in Renal Disease 1 (for six variables), MDRD 2: Modification of Diet in Renal Disease 2 (for four variables), IDMS: Isotope dilution mass spectrometry, CKD-EPI: Chronic Kidney Disease Epidemiology Collaboration.

†Isotope dilution mass spectrometry traceable creatinine was used.

Figure 1. Iohexol measured and estimated glomerular filtration rate and confidence limits for various formulae (n = 229). Notes: GFR: Glomerular filtration rate, MDRD 1: Modification of Diet in Renal Disease 1 (for six variables), MDRD 2: Modification of Diet in Renal Disease 2 (for four variables), IDMS: Isotope dilution mass spectrometry, CKD - EPI: Chronic Kidney Disease Epidemiology Collaboration. *GFR was expressed as mL/min. **Isotope dilution mass spectrometry traceable creatinine was used.

Figure 2. (a) The estimated glomerular filtration rates according to different estimations equations tabulated by iohexol measured glomerular filtration rate values (GFR < 30 mL/min/1.73 m², n = 97). Notes: GFR: Glomerular filtration rate, MDRD 1: Modification of Diet in Renal Disease 1 (for six variables), MDRD 2: Modification of Diet in Renal Disease 2 (for four variables), IDMS: Isotope dilution mass spectrometry, CKD - EPI: Chronic Kidney Disease Epidemiology Collaboration. *GFR was expressed as mL/min. **Isotope dilution mass spectrometry traceable creatinine was used. (b) The estimated glomerular filtration rates according to different estimations equations tabulated by iohexol measured glomerular filtration rate values (GFR 30 – 60 mL/min/1.73 m², n = 79). Notes: GFR: Glomerular filtration rate, MDRD 1: Modification of Diet in Renal Disease 1 (for six variables), MDRD 2: Modification of Diet in Renal Disease 2 (for four variables), IDMS: Isotope dilution mass spectrometry, CKD - EPI: Chronic Kidney Disease Epidemiology Collaboration. *GFR was expressed as mL/min. **Isotope dilution mass spectrometry traceable creatinine was used. (c) The estimated glomerular filtration rates according to different estimations equations tabulated by iohexol measured glomerular filtration rate values (GFR > 60 mL/min/1.73 m², n = 53). Notes: GFR: Glomerular filtration rate, MDRD 1: Modification of Diet in Renal Disease 1 (for six variables), MDRD 2: Modification of Diet in Renal Disease 2 (for four variables), IDMS: Isotope dilution mass spectrometry, CKD - EPI: Chronic Kidney Disease Epidemiology Collaboration. *GFR was expressed as mL/min. **Isotope dilution mass spectrometry traceable creatinine was used.

Figure 3. Bland–Altman analysis showing the agreement between iohexol measured glomerular filtration rate and modified MDRD formula (multiplied with the correction coefficient). Notes: GFR: Glomerular filtration rate, MDRD: Modification of Diet in Renal Disease.

Figure 4. Classification performance of various estimation equations. Notes: GFR: Glomerular filtration rate, MDRD 1: Modification of Diet in Renal Disease 1 (for six variables), MDRD 2: Modification of Diet in Renal Disease 2 (for four variables), IDMS: Isotope dilution mass spectrometry, CKD – EPI: Chronic Kidney Disease Epidemiology Collaboration. *Isotope dilution mass spectrometry traceable creatinine was used.

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