title: Application of a point of care creatinine device for trend monitoring in kidney transplant patients: fit for purpose?
abstract: BACKGROUND
  The StatSensor® Xpress-i™, a point-of-care system for blood creatinine measurement, offers patients the possibility of self-monitoring creatinine. In this study, the analytical performance of the StatSensor® for both detecting current renal function and monitoring renal (dys)function in kidney transplant patients was examined.
  
  
  METHODS
  Accuracy of the StatSensor® with capillary and venous whole blood was evaluated and compared to an isotopic dilution mass spectrometry (IDMS)-traceable enzymatic creatinine test in venous serum (n=138). Twenty Li-heparin samples were compared to the IDMS reference method performed by a Joint Committee for Traceability in Laboratory Medicine (JCTLM)-listed reference laboratory (RfB, Bonn, Germany). To evaluate StatSensor®'s suitability to monitor kidney function, both venous and capillary samples were obtained in 20 hospitalized transplantation patients. Venous samples were analyzed with an IDMS-traceable enzymatic test, capillary samples were measured using the StatSensor®. For all 2-day intervals, percentage change in creatinine was compared between both methods.
  
  
  RESULTS
  The StatSensor® did not meet total allowable error criterion of 6.9%. Average overall CVa for the StatSensor® was 10.4% and 5.2% for capillary and venous whole blood results, respectively. Overall CVa for the central laboratory serum creatinine method was <1.5%. For monitoring renal (dys)function, total agreement of the StatSensor® with an IDMS-traceable enzymatic test was 68% using a 10% Δ change. No significant differences were found between the changes observed by both methods.
  
  
  CONCLUSIONS
  Capillary blood testing with the StatSensor® is not advisable for determining current renal function with a single creatinine measurement in kidney transplant patients, mainly due to excessive analytical imprecision. However, our results suggest that capillary blood testing with the StatSensor® can be used for daily trend monitoring of kidney function after renal transplantation.
authors.forename: Céline L
authors.initials: CL
authors.lastname: van Lint
authors.forename: Paul J M
authors.initials: PJ
authors.lastname: van der Boog
authors.forename: Fred P H T M
authors.initials: FP
authors.lastname: Romijn
authors.forename: Paul W
authors.initials: PW
authors.lastname: Schenk
authors.forename: Sandra
authors.initials: S
authors.lastname: van Dijk
authors.forename: Ton J M
authors.initials: TJ
authors.lastname: Rövekamp
authors.forename: Anja
authors.initials: A
authors.lastname: Kessler
authors.forename: Lothar
authors.initials: L
authors.lastname: Siekmann
authors.forename: Ton J
authors.initials: TJ
authors.lastname: Rabelink
authors.forename: Christa M
authors.initials: CM
authors.lastname: Cobbaert
mesh_terms: D000328:Adult; D001774:Blood Chemical Analysis / Q000295:instrumentation* / Q000379:methods; D003404:Creatinine / Q000097:blood*; D005260:Female; D005919:Glomerular Filtration Rate; D006403:Hematologic Tests / Q000295:instrumentation / Q000379:methods; D006801:Humans; D007677:Kidney Function Tests / Q000379:methods; D016030:Kidney Transplantation / Q000379:methods*; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000295:instrumentation / Q000379:methods; D019095:Point-of-Care Systems; D015203:Reproducibility of Results
chemical_list: D003404:Creatinine