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Abstract: TH-PO1093

Comparing Glomerular Filtration Rate Measured by Radionuclide Imaging with Creatinine Based Equations

Session Information

Category: CKD (Non-Dialysis)

  • 1902 CKD (Non-Dialysis): Clinical, Outcomes, and Trials

Authors

  • Gonzalez, Camilo A., Hospital Universitario San Ignacio, Bogota, Bogota D.C, Colombia
  • Durán, Alejandro, Pontificia Universidad Javeriana, Bogota, Bogota D.C., Colombia
  • Vargas, María T., Pontificia Universidad Javeriana, Bogota, Bogota D.C., Colombia
  • Garcia, Paola, Hospital Universitario San Ignacio, Bogota, Bogota D.C, Colombia
  • Rodriguez, Patricia, Hospital Universitario San Ignacio, Bogota, Bogota D.C, Colombia
  • Contreras, Kateir, Hospital Universitario San Ignacio, Bogota, Bogota D.C, Colombia
Background

Glomerular filtration rate (GFR) is the best index of kidney function. Creatinine based equations (CBE) are recomended by guidelines. In Colombia sometimes we use radionuclide imaging(RI) with 99mTc-DTPA to measure GFR thinking that it could be better. The aim of this study is to estimate correlation and concordance between this method and eGFR with CBE.

Methods

We included patients who had standarized creatinine and GFR meassured with 99mTc-DTPA RI in the same week from 4 institutions in Bogota, Colombia between November 2008 and October 2017. We excluded patients with expected source of error in CBE and RI. CBE used were CKD-EPI, MDRD4 and Cockcroft Gault adjusted to body surface (CGa). We estimated the correlation with Spearman coefficient and concordance with kappa coefficient for CKD diagnosis (<60ml/min/1.73m2) and CKD grades. We considered p<0.05 as statistically significant.

Results

We included 421 patients. Mean age 54 years (± 17.1), 46.8% female, mean eGFR 75.9 (± 26.6), 76.3 (± 28.8), 77.1 (± 31.6) and 77.9 (±28.4) ml/min/1.73m2 with CKD-EPI, MDRD4, CGa and RI respectively; 29.4% had eGFR less than 60. There were no differences of mean. In the graph, we show the distribution by grades of CKD. The correlation was good between equations, but acceptable when comparing CBE with 99mTc-DTPA RI. Weighted kappa concordance between CBEs was good but for 99mTc-DTPA RI compared to all CBE was fair.(Table)

Conclusion

GFR with 99mTc-DTPA RI had a low correlation and fair concordance compared with CBE. There are no reasons to consider RI as a better tool. And also, is an expensive test with limited availability.

Spearman coeficiente and weighted Kappa coefficient by CKD grades 1 to 5.
 CKD-EPIMDRD499mTc-DTPA
MDRD4ρ=0.98 κ=0.92  
CGaρ=0.94 κ=0.82ρ=0.91 κ=0.75ρ=0.50 κ=0.36
99mTc-DTPAρ=0.57 κ=0.40ρ=0.55 κ=0.39 

All p<0.00001