Page 93 - Exploring the Potential of Self-Monitoring Kidney Function After Transplantation - Céline van Lint

Application of a creatinine device for trend monitoring 91
Figure 5: Agreement between blood creatinine changes in capillary finger prick (FP) whole blood measured with the StatSensor® (Cr change) and in venous serum measured with the Modular P800 (sCr change) has been evaluated. Both a Deming regression plot (left) and the corresponding difference plot (right) are presented.
DISCUSSION
In the current study, we examined the suitability of the StatSensor® Xpress-iTM, a handheld POC system for creatinine measurement. We analyzed its performance for both detecting current renal function of kidney transplant patients with a single creatinine measurement and monitoring creatinine trends with serial creatinine measurements. From the reference standardization study it becomes clear that the traceability of capillary StatSensor® creatinine results to the creatinine reference system is inadequate. The split-sample comparison study showed that CVa of the StatSensor® is excessive compared to the predefined desirable CVa criterion based on biological variation [22], leading to 2.25-fold increased RCVs as compared to the central laboratory method (Table 1). Therefore, the StatSensor® device does not fulfill desirable nor minimum analytical performance criteria in case of using capillary blood. As such, the StatSensor® is not suitable for detecting current renal function of kidney transplant patients with a single creatinine measurement. These findings are in agreement with previous studies which showed insufficient analytical validity of the StatSensor® [19, 20] compared to IDMS-standardized enzymatic methods in the central laboratory. Improving the analytical performance of the StatSensor®, in line with IVD 98/79/EC directive and the ISO 15189 guideline, could improve the potential for using StatSensor® creatinine capillary testing for kidney diagnostic use. Figure 3B illustrates the perfect
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