Page 85 - Exploring the Potential of Self-Monitoring Kidney Function After Transplantation - Céline van Lint

Application of a creatinine device for trend monitoring 83
0932/cclm-2014-0932.xml?format=INT ). Serum creatinine in the hospital central laboratory is performed with an IDMS-traceable enzymatic method on the Roche Modular P800, Cat Nr. 11875566216 (Reagent 1) and 11875582216 (Reagent 2) for the Creatinine Plus assay and Cat Nr. 10759350190 for the C.f.a.s. (calibrator for automated systems) calibrator (Roche Diagnostics, Mannheim, Germany).
Methods
Evaluation of StatSensor®’s performance for detecting current renal function of kidney transplant patients
The analytical performance of the StatSensor® was evaluated and compared to the performance of an IDMS traceable enzymatic creatinine central laboratory method using specimens of kidney transplant patients who had their regular outpatient hospital appointment in July 2011. All patients received a letter about the study and the informed consent procedure. We used a ‘yes, unless’ principle, with all invited patients enrolled unless they declined participation.
Participation comprised of the donation of an extra tube of blood and the performance of two capillary creatinine measurements. After collecting venous blood samples for routine analyses (including analysis of serum creatinine concentration), an additional lithium heparin tube was taken. Participating patients then visited a doctors’ assistant to measure capillary whole blood creatinine with the StatSensor® on the spot. Five different StatSensor® devices were randomly used. Capillary punctures were performed in duplicate (middle and ring finger). Based on the average of the duplicate StatSensor® measurements, patients were grouped into three creatinine categories: 50–100, 100–200 and >200 μmol/L. The first 30 patients allocated to one of these categories were selected for further analysis. In addition, eight patients with large differences between the duplicate measurements were selected for further assessment. In our central laboratory, creatinine was repetitively measured (2- and 5-fold) by an experienced technician in lithium heparinized blood on the patient-specific StatSensor® meters, i.e., the ones used for testing the capillary finger pricks. Residual lithium heparinized whole blood was centrifuged at 2750 g for 15 min at room temperature (RT). The obtained plasma was used to determine creatinine according to the central laboratory method. Residual plasma was stored at –80 °C. All lithium heparinized blood was analyzed within 4 h from blood drawing. A subset of 20 stored plasma samples was sent to the Reference Institute for Bioanalytics (RfB) in Bonn, Germany for objective evaluation of StatSensor® bias as compared to the Joint Committee for Traceability in Laboratory Medicine (JCTLM)-listed IDMS reference method (www.bipm.org/BIPM
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