Concordance between estimated glomerular filtration rate using equations and that measured using an imaging method.

BACKGROUND: Guidelines recommend estimating glomerular filtration rate (GFR) using creatinine-based equations (CBE). AIM: To evaluate the agreement between GFR measured using radionuclide imaging and estimated using creatinine-based equations. MATERIAL AND METHODS: In 421 patients aged 54 ± 17 years (47% women) GFR was estimated using the MDRD-4, CKD-EPI and the body surface adjusted Cockroft Gault equation. GFR was also measured using a radionuclide imaging method with 99mTc-DTPA. The concordance between estimated and measured GFR was calculated using Lin's concordance coefficient and Bland and Altman plots. RESULTS: Average GFR values obtained with CKD-EPI, MDRD-4, body surface adjusted Cockroft Gault equation and 99mTc-DTPA imaging were 75.9 ± 26.6, 76.3 ± 28.8, 77.1 ± 31.6 and 77.9 ± 28.4 ml/min/1.73 m2, respectively. There was no significant difference in means and 29% of participants had a GFR < 60 ml/min/1.73 m2 by CKD-EPI. The correlation was good between equations, but acceptable when compared with the 99mTc-DTPA imaging. The weighted kappa between CBEs was good, but low when comparing CBEs with measured GFR. The Lin's concordance coefficient between estimated and measured GFR was low. CONCLUSIONS: GFR measured by 99mTc-DTPA radionuclide imaging has a low correlation and poor concordance with estimations using CBE.

Concordance between estimated glomerular filtration rate using equations and that measured using an imaging method

ABSTRACT Background: Guidelines recommend estimating glomerular filtration rate (GFR) using creatinine-based equations (CBE). Aim: To evaluate the agreement between GFR measured using radionuclide imaging and estimated using creatinine-based equations. Material and Methods: In 421 patients aged 54 ± 17 years (47% women) GFR was estimated using the MDRD-4, CKD-EPI and the body surface adjusted Cockroft Gault equation. GFR was also measured using a radionuclide imaging method with 99mTc-DTPA. The concordance between estimated and measured GFR was calculated using Lin's concordance coefficient and Bland and Altman plots. Results: Average GFR values obtained with CKD-EPI, MDRD-4, body surface adjusted Cockroft Gault equation and 99mTc-DTPA imaging were 75.9 ± 26.6, 76.3 ± 28.8, 77.1 ± 31.6 and 77.9 ± 28.4 ml/min/1.73 m2, respectively. There was no significant difference in means and 29% of participants had a GFR < 60 ml/min/1.73 m2 by CKD-EPI. The correlation was good between equations, but acceptable when compared with the 99mTc-DTPA imaging. The weighted kappa between CBEs was good, but low when comparing CBEs with measured GFR. The Lin's concordance coefficient between estimated and measured GFR was low. Conclusions: GFR measured by 99mTc-DTPA radionuclide imaging has a low correlation and poor concordance with estimations using CBE.

Antecedentes: Las guías clínicas recomiendan estimar la tasa de filtración glomerular (TFG) usando ecuaciones basadas en la creatinina sérica. Objetivo: Estudiar la concordancia entre la TFG medida usando un método de imágenes usando radioisótopos y aquella estimada con ecuaciones. Material y Métodos: En 421 pacientes de 54 ± 17 años (47% mujeres), la TFG se estimó utilizando las ecuaciones MDRD-4, CKD-EPI y Cockroft Gault ajustada para superficie corporal. La TFG se midió también con una técnica de imágenes usando 99mTc-DTPA. La concordancia entre la estimación y medición se calculó usando el coeficiente de concordancia de Lin y gráficos de Bland y Altman. Resultados: Los promedios de TFG obtenidos con CKD-EPI, MDRD-4, ecuación de Cockroft Gault e imágenes con 99mTc-DTPA fueron 75,9 ± 26,6, 76,3 ± 28,8, 77,1 ± 31,6 y 77,9 ± 28,4 ml/min/1,73 m2, respectivamente. No hubo diferencias significativas en los promedios y el 29% de los participantes tuvo una TFG < 60 ml/min/1,73 m2. La correlación entre las ecuaciones fue buena, pero sólo aceptable cuando se comparó con la medición por imágenes. El kappa ajustado entre las ecuaciones fue adecuado, pero malo cuando se comparó las ecuaciones con la medición por imágenes. El coeficiente de Lin mostró una baja concordancia entre la estimación y medición de TFG. Conclusiones: La concordancia entre la estimación de TFG usando ecuaciones y su medición directa mediante imágenes es baja.