Estimation of glomerular filtration rate in hospitalised patients: are we overestimating renal function?

Swiss Med Wkly. 2012 Dec 19:142:w13708. doi: 10.4414/smw.2012.13708. eCollection 2012.

Abstract

QUESTIONS UNDER STUDY AND PRINCIPLES: Estimating glomerular filtration rate (GFR) in hospitalised patients with chronic kidney disease (CKD) is important for drug prescription but it remains a difficult task. The purpose of this study was to investigate the reliability of selected algorithms based on serum creatinine, cystatin C and beta-trace protein to estimate GFR and the potential added advantage of measuring muscle mass by bioimpedance.

Methods: In a prospective unselected group of patients hospitalised in a general internal medicine ward with CKD, GFR was evaluated using inulin clearance as the gold standard and the algorithms of Cockcroft, MDRD, Larsson (cystatin C), White (beta-trace) and MacDonald (creatinine and muscle mass by bioimpedance).

Results: 69 patients were included in the study. Median age (interquartile range) was 80 years (73-83); weight 74.7 kg (67.0-85.6), appendicular lean mass 19.1 kg (14.9-22.3), serum creatinine 126 μmol/l (100-149), cystatin C 1.45 mg/l (1.19-1.90), beta-trace protein 1.17 mg/l (0.99-1.53) and GFR measured by inulin 30.9 ml/min (22.0-43.3). The errors in the estimation of GFR and the area under the ROC curves (95% confidence interval) relative to inulin were respectively: Cockcroft 14.3 ml/min (5.55-23.2) and 0.68 (0.55-0.81), MDRD 16.3 ml/min (6.4-27.5) and 0.76 (0.64-0.87), Larsson 12.8 ml/min (4.50-25.3) and 0.82 (0.72-0.92), White 17.6 ml/min (11.5-31.5) and 0.75 (0.63-0.87), MacDonald 32.2 ml/min (13.9-45.4) and 0.65 (0.52-0.78).

Conclusions: Currently used algorithms overestimate GFR in hospitalised patients with CKD. As a consequence eGFR targeted prescriptions of renal-cleared drugs, might expose patients to overdosing. The best results were obtained with the Larsson algorithm. The determination of muscle mass by bioimpedance did not provide significant contributions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • Algorithms
  • Creatinine / blood*
  • Cystatin C / blood*
  • Electric Impedance
  • Glomerular Filtration Rate*
  • Humans
  • Inpatients / statistics & numerical data
  • Intramolecular Oxidoreductases / blood*
  • Lipocalins / blood*
  • Muscle, Skeletal / anatomy & histology
  • Prospective Studies
  • ROC Curve
  • Renal Insufficiency, Chronic / blood
  • Renal Insufficiency, Chronic / physiopathology*
  • Reproducibility of Results
  • Switzerland

Substances

  • Cystatin C
  • Lipocalins
  • Creatinine
  • Intramolecular Oxidoreductases
  • prostaglandin R2 D-isomerase