Differences in Kidney Function Estimates Based on Creatinine and/or Cystatin C in Non-Traumatic Amputation Patients and Their Impact on Drug Prescribing

• Published in: Journal of clinical medicine 2019-01, Vol.8 (1), p.89
• Main Authors: Aakjær, Mia, Houlind, Morten B, Treldal, Charlotte, Ankarfeldt, Mikkel Z, S Jensen, Pia, Andersen, Ove, Iversen, Esben, Christrup, Lona L, Petersen, Janne
• Format: Article
• Language: English
• ISSN: 2077-0383; 2077-0383
• DOI: 10.3390/jcm8010089

Accurate kidney function estimates are necessary when prescribing renally-eliminated medications. Our objectives were to investigate how amputation affects estimated glomerular filtration rate (eGFR) and to determine if dosing recommendations differ among different eGFR equations. In a cohort study of non-traumatic amputation patients, eGFR based on creatinine and/or cystatin C were measured before and after amputation. Prescribed, renally-eliminated medications were compared with dosing guidelines in Renbase . Data from 38 patients with a median age of 75 years were analyzed. The median (range) eGFR was 65 (15⁻103), 38 (13⁻79), and 48 (13⁻86) mL/min/1.73 m² before amputation and 80 (22⁻107), 51 (13⁻95), and 62 (16⁻100) mL/min/1.73 m² after amputation for eGFR , eGFR , and eGFR , respectively ( < 0.01). From before to after amputation, eGFR increased on average by 8.5, 6.1, and 7.4 mL/min/1.73 m² for eGFR , eGFR , and eGFR (all < 0.01), respectively. At least one renally-eliminated medication was prescribed at a higher dose than recommended in 37.8% of patients using eGFR , 17.6% using eGFR and 10.8% using eGFR . In conclusion, amputation affects eGFR regardless of the eGFR equations. The differences among equations would impact prescribing of renally-eliminated medications, particularly when switching from creatinine to cystatin C.