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Abstract: PO1888

Comparison of Kidney Volume-Based Methodology to Glomerular Filtration Rate Estimating Equations to Predict Measured Glomerular Filtration Rate in Cancer Patients

Session Information

Category: Onco-Nephrology

  • 1500 Onco-Nephrology

Authors

  • Bezerra, Regis Franca, ICESP, Sao Paulo, SP, Brazil
  • Dantas, Patricia Perola, ICESP, Sao Paulo, SP, Brazil
  • Freire, Filipe de Andrade, ICESP, Sao Paulo, SP, Brazil
  • Sapienza, Marcelo T., Universidade de Sao Paulo Hospital das Clinicas, Sao Paulo, SP, Brazil
  • Levey, Andrew S., Tufts University, Medford, Massachusetts, United States
  • Inker, Lesley Ann, Tufts University, Medford, Massachusetts, United States
  • Costa e Silva, Veronica Torres, ICESP, Sao Paulo, SP, Brazil
Background

Total kidney volume (TKV) has been associated with both measured glomerular filtration rate (mGFR) and with equations recommended to estimate GFR (eGFR) in clinical practice. However, there is scarce data comparing measurement of TKV to eGFR equations as predictors of mGFR, particularly in the oncology setting.

Methods

We enrolled 181 cancer patients treated at an academic tertiary cancer hospital in Brazil (Instituto do Câncer do Estado de São Paulo), who had undergone abdominal imaging and measurement of GFR by plasma clearance of 51Cr-EDTA within 60 days. eGFR was determined based on the CKD-EPI equation using Scr (eGFRcr) and Scr combined with Scys (eGFRcr-cys). eGFR and mGFR were non indexed for body surface area. Total kidney volume (TKV) was measured using a semi-automatic segmentation program, excluding non-functional tissues. The correlations between mGFR and TKV as well as mGFR and eGFR were calculated using the Pearson correlation coefficient. Linear regression models for mGFR having TKV and eGFR equations as predictors were built.

Results

Patients were 55 (14.0) y, 50.3% male. Most common cancer sites were breast (22.7%), male genital (21.8%) and gastrointestinal (20.9%). ECOG levels 0/1 corresponded to 95% of patients.
Mean (SD) Body mass index was 27.18 (5.18). Mean (SD) mGFR, eGFRcr and eGFRcr-cys were 84.8(27.23), 90.4 (24.9), and 83.8 (25.9), ml/min, respectively. Mean (SD) TKV for both kidneys was 302.2 (77.9) cm3.
PCC for mGFR-TKV, mGFR-eGFRcr and mGFR-eGFRcr-cys were 0.76, 0.78 and 0.85, respectively. TKV improved the coefficient of determination of the linear regression models when added to both eGFRcr and eGFRcr-cys, in overall and assessed subgroups (Table 1).

Conclusion

In conclusion, our results suggest that measurement of TKV is a reliable predictor of mGFR in cancer patients with the potential to be incorporated to the current eGFR equations used in clinical practice.