Performance of creatinine-based equations for estimating glomerular filtration rate compared to endogenous creatinine clearance

Gisele da Silva da Fonseca

Universidade de Caxias do Sul, Programa de Pós-Graduação em Ciências da Saúde Brasil, Caxias do Sul, RS, Brasil.

Vandréa Carla de Souza

Universidade de Caxias do Sul, Programa de Pós-Graduação em Ciências da Saúde Brasil, Caxias do Sul, RS, Brasil.

Hospital Geral de Caxias do Sul, Caxias do Sul, RS, Brasil.

Sarah Assoni Bilibio

Universidade de Caxias do Sul, Caxias do Sul, RS, Brasil.

Vanessa Carobin

Universidade de Caxias do Sul, Caxias do Sul, RS, Brasil.

Lígia Facin

Hospital Geral de Caxias do Sul, Caxias do Sul, RS, Brasil.

Ketelly Koch

Universidade de Caxias do Sul, Caxias do Sul, RS, Brasil.

Morgana Machado

Universidade de Caxias do Sul, Caxias do Sul, RS, Brasil.

Laurence Dubourg

Université Claude Bernard Lyon 1, Lyon, França.

Luciano da Silva Selistre Correspondence to: Luciano da Silva Selistre. E-mail: lsselist@ucs.br

Universidade de Caxias do Sul, Programa de Pós-Graduação em Ciências da Saúde Brasil, Caxias do Sul, RS, Brasil.

Hospital Geral de Caxias do Sul, Caxias do Sul, RS, Brasil.

Authors’ Contribution

LSS had full access to the study data and was responsible for the completeness and accuracy of the data analysis. GSF, VCS, LF, MM, KK, VC, SAB, LD, LSS study concept and design. GSF, LF, LSS data acquisition. GSF, LS data analysis and interpretation. LSS, VCS, LD, LSS critical review of the manuscript for intellectual content. LSS, VCS, LD administrative, technical or material support.

Conflict of Interest

We certify that this manuscript represents an original work and that neither it, in part or in full, nor any other work with substantially similar content, of my authorship, has been published or is being considered for publication in another journal, whether in print or electronic format.

The authors have no conflict of interest in relation to this work.

MDRD*	$eGFR = 175 \times {(SCr)}^{- 1.154} \times [0.742 if women] \times [1.159 if {black}^{*}]$
CKD-EPI	$Women; SCr \leq, eGFR = 144 \times {[\frac{SCr}{0.7}]}^{- 0.329} \times {[0.993]}^{Age}$
	$Women; SCr > 0.7, eGFR = 144 \times {[\frac{SCr}{0.7}]}^{- 1.209} \times {[0.993]}^{Age}$
	$Men; SCr \leq 0.9, GFR = 141 \times {[\frac{SCr}{0.9}]}^{- 0.411} \times {[0993]}^{Age} \times [1.159 if {black}^{*}]$
	$Men; SCr > 0.9, eGFR = 141 \times {[\frac{SCr}{0.9}]}^{- 1.209} \times {[0.993]}^{Age} \times [1.159 if {black}^{*}]$
CKD-EPI local	$Women; SCr \leq 0.8, eGFR = 144 \times {[\frac{SCr}{0.8}]}^{- 0.329} \times {[0.993]}^{Age}$
	$Women; SCr > 0.8, eGFR = 144 \times [\frac{SCr}{0.8}] - 1.209 \times {[0.993]}^{Age}$
	$Men; SCr \leq 1.0, GFR = 141 \times {[\frac{SCR}{1.0}]}^{- 0.411} \times {[0.993]}^{Age} \times [1.159 if {black}^{*}]$
	$Men; SCr > 1.0, eGFR = 141 \times [\frac{SCr}{1.0}] - 1.209 \times {[0.993]}^{Age} \times [1.159 if {black}^{*}]$
FAS	$Age \leq 40 years : eGFR = 107.3 \times \frac{SCr}{1.0}$
	$Age > 40 years : eGFR = 107.3 \times \frac{SCr}{1.0} \times 0.988^{Age - 40}$
	$Q = 1.0 \frac{mg}{dL} inMen and \frac{0.8 mg}{dL} in Women$

Characteristics	Total population	ClCr < 60 mL/min/1.73 m²
Number of participants, n (%)	1.281 (100.0)	320 (25.5)
Mean age [IQR], years	53.0 [38.0; 65.0]	61.0 (49.0; 72.0)
≥ 65 years, n (%)	325 (26.5)	136 (42.5)
Females, n (%)	485 (38.0)	85 (25.5)
Median weight [IQR], Kg	74.0 [65.0; 85.0]	70.0 [65.0; 80.0]
Median height [IQR], cm	169 [162; 175]	170 [162; 175]
Median body surface [IQR], m²	1.84 [1.71; 1.98]	1.81 [1.70; 1.93]
Median BMI [IQR], Kg/m²	26.0 [24.0; 29.0]	25.0 [23.0; 28.0]
BMI ≥ 30.0, n (%)	255 (20.0)	56 (16.5)
Median serum creatinine [IQR], mg/dL	1.10 [0.80; 1.50]	2.90 [1.88; 4.30]
Median ClCr [IQR], mL/min/1.73 m²	94.0 [60.0; 124.0]	31.0 [21.0; 44.0]

	Median ratio	IQR	LoA 2,5%	LoA 97,5%	P₃₀ Accuracy	Spearman’s coefficient
	(CI 95%)	(CI 95%)	(CI 95%)	(CI 95%)	(CI 95%)	(CI 95%)
Entire Population (N 1,281)
MDRD	0.74	0.18	0.47	0.98	50.5	0.895
	(0.51; 0.76)	(0.17; 0.19)	(0.44; 0.49)	(0.95; 1.02)	(45.0; 56.5)	(0.881; 0.915)
CKD-EPI	1.15	0.18	0.66	1.65	58.7	0.900
	(1.12; 1.17)	(0.17; 0.20)	(0.64; 0.69)	(1.62; 1.67)	(56.0; 61.6)	(0.881; 0.916)
CKD-EPI local	0.75	0.23	0.45	1.00	90.5	0.893
	(0.73; 0.77)	(0.22; 0.24)	(0.42; 0.47)	(0.98; 1.27)	(88.7; 92.0) ^‡ ‡ P < 0.01 favoring CKD-EPI local	(0.873; 0.910)
FAS	0.92	0.22	0.63	1.29	82.0	0.908
	(0.89; 0.94)^* * P < 0.01 favoring FAS;	(0.21; 0.23)	(0.60; 0.67)	(1.24; 1.33)	(79.7; 84.0)	(0.888; 0.922)
Population with EEC < 60 mL/min/1.73 m² (N = 320)
MDRD	0.65	0.20	0.37	0.86	53.0	0.880
	(0.62; 0.70)	(0.17; 0.22)	(0.28; 0.45)	(0.80; 1.04)	(47.0; 58.5)	(0.832; 0.916)
CKD-EPI	0.63	0.20	0.37	0.88	52.0	0.880
	(0.61; 0.68)	(0.18; 0.23)	(0.17; 0.40)	(0.86; 0.98)	(46.0; 58.0)	(0.830; 0.918)
CKD-EPI local	0.90	0.29	0.51	1.26	85.5	0.878
	(0.86; 0.98) ^‡ ‡ P < 0.01 favoring CKD-EPI local	(0.24; 0.32)	(0.24; 0.53)	(1.25; 1.50)	(81.0; 90.0) ^‡ ‡ P < 0.01 favoring CKD-EPI local	(0.827; 0.915)
FAS	1.05	0.24	0.60	1.40	88.0	0.862
	(0.97; 1.09) ^‡ ‡ P < 0.01 favoring CKD-EPI local	(0.20; 0.29)	(0.49; 0.68)	(1.39; 1.51)	(84.0; 92.0) ^‡ ‡ P < 0.01 favoring CKD-EPI local	(0.811; 0.901)

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