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Kidney Week

Abstract: TH-PO396

Performance of Creatinine-Based GFR Estimates in Patients on Ritonavir-Boosted Protease Inhibitors

Session Information

Category: CKD (Non-Dialysis)

  • 2101 CKD (Non-Dialysis): Epidemiology, Risk Factors, and Prevention

Authors

  • Chaudhari, Juhi, Tufts Medical Center, Boston, Massachusetts, United States
  • Wyatt, Christina M., Duke University School of Medicine, Durham, North Carolina, United States
  • Miao, Shiyuan, Tufts Medical Center, Boston, Massachusetts, United States
  • Krishnasami, Zipporah, Medical University of South Carolina, Charleston, South Carolina, United States
  • Levey, Andrew S., Tufts Medical Center, Boston, Massachusetts, United States
  • Ross, Michael J., Albert Einstein College of Medicine/ Montefiore Medical Center, Bronx, New York, United States
  • Ryom, Lene, CHIP, Department of infectious diseases, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
  • Mocroft, Amanda, University College London, London, United Kingdom
  • Brunet, Laurence, Epividian, Inc., Durham, North Carolina, United States
  • Fusco, Jennifer S., Epividian, Inc., Durham, North Carolina, United States
  • Inker, Lesley, Tufts Medical Center, Boston, Massachusetts, United States
Background

The pharmacoenhancer ritonavir has been shown to inhibit tubular transport of creatinine in vitro. We aimed to determine whether use of ritonavir-boosted protease inhibitors (PI/r) affects the performance of creatinine-based GFR estimates.

Methods

We previously measured GFR (mGFR) in 200 HIV-positive adults on stable antiretroviral therapy using plasma iohexol clearance. We evaluated performance of the CKD-EPI creatinine equation (CKD-EPIcr), MDRD Study equation, and Cockcroft-Gault creatinine clearance (indexed to 1.73m2 body surface area) versus mGFR. We compared bias (median difference between mGFR and estimated GFR) and accuracy (percent of estimates within 30% of mGFR, with large errors indicated by 1-P30). Statistical significance of the differences in bias and accuracy were tested by Wilcoxon two-sample test and chi-square test, respectively.

Results

73% of the population was male, 52% of Black race, and 34% over the age of 50 years. 61% were virologically suppressed and 44% were on a PI/r. No participants were taking other antiretrovirals known to inhibit creatinine secretion. The CKD-EPICr equation performed better than other equations. There were no clinically or statistically significant differences in the performance of any equation between the PI/r and no-PI/r groups (Figure).

Conclusion

Use of PI/r did not have a significant impact on the performance of creatinine-based GFR estimates as compared to mGFR. Declines in eGFR with the use of PI/r may reflect real changes in kidney function.

Performance of creatinine-based estimating equations in patients on PI/r versus no PI/r
Left: Bias; Right: Accuracy; PI/r, ritonavir-boosted protease inhibitor; GFR, glomerular filtration rate; CKD-EPIcr, GFR by CKD-EPI creatinine equation; MDRD, GFR by MDRD Study equation; CG, creatinine clearance by Cockcroft-Gault equation indexed to 1.73m2 body surface area. Error bars represent 95% confidence intervals.

Funding

  • Other NIH Support