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Abstract: SA-PO829

The Effect of Weight, Body Mass Index, and Body-Surface-Area on the Agreement Between Estimated and Measured GFR in Heart Transplant Recipients

Session Information

Category: Transplantation

  • 2002 Transplantation: Clinical

Authors

  • Jørgensen, Morten Buus, Department of Nephrology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
  • Hornum, Mads, Department of Nephrology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
  • Nelson, Lærke Marie Sidenius, Department of Cardiology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
  • Feldt-Rasmussen, Bo, Department of Nephrology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
  • Rossing, Kasper, Department of Cardiology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
  • Porrini, Esteban, Faculty of Medicine, Instituto de Tecnologías Biomédicas (ITB), University of La Laguna, La Laguna, Spain
  • Gustafsson, Finn, Department of Cardiology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
Background

Assessing glomerular filtration rate (GFR) in heart transplant (HTx) recipients is paramount to adjust immunosuppressive, anti-bacterial, and anti-viral therapy. Estimated GFR (eGFR) has shown poor agreement with measured GFR (mGFR) in populations with changing body composition yielding HTx recipients at risk of suboptimal treatment as weight gain and weight loss are frequent complications to HTx. We investigated the effect of weight, BMI and body-surface-area (BSA) on the accuracy and precision of eGFR in HTx recipients.

Methods

In a longitudinal, observational, retrospective study-design, patients receiving first-time HTx with at least one registered mGFR within 15 months after HTx and a corresponding plasma creatinine were included. GFR was measured by 51Cr-EDTA. eGFR adjusted for BSA was calculated by creatinine-based CKD-EPI formula and eGFR not adjusted for BSA was calculated using Dubois and DuBois. Longitudinal data were analyzed within a linear mixed model and cross-sectional data were analyzed using Bland Altman analysis and ANOVA.

Results

150 patients with a total of 723 mGFR measurements were included. During the first year after HTx, mean weight increased by 4.2 kg (CI: 3.2 to 5.1) followed by an annual decrease of 0.35 kg/year (Cl: -0.05 to 0.74). mGFR increased by 7.5 ml/min (Cl: 3.2 to 11.8) the first year but was stable hereafter (0.0 ml/min/year, CI: -1.0 to 1.0). The initial weigh gain and increase in mGFR were most pronounced in patients <45 years. Neither eGFR adjusted nor unadjusted for BSA detected the initial increase in mGFR.

At one year after HTx, limits of agreement of the Bland Altman plot were -37.2 to 33.1 ml/min with a bias of -2.1 ml/min (Cl: -5.0 to 0.9). In patients <45 years, eGFR significantly overestimated mGFR by 7.1 ml/min (Cl: 1.0 to 13.2) and showed a significant lower precision than patients >45 years. The overestimation of mGFR was persistent after the first posttransplant year. There was no effect of weight, BMI, BSA or change in BMI class on the difference between eGFR and mGFR.

Conclusion

In heart transplant recipients, eGFR was, on average, very accurate and was not affected by body composition. The precision was, however, very low and eGFR performed poorly especially in younger patients.