Page 181 - Exploring the Potential of Self-Monitoring Kidney Function After Transplantation - Céline van Lint
P. 181

 transplant patients completed the questionnaire before and after having used the SMSS for 4 months. Patients were found to be on average positive towards using the SMSS, both in advance of use and after having used the SMSS for 4 months. Behavioural intention could mostly be explained by patients’ affect towards the SMSS (26% explained variance), with affect referring to whether patients liked to use the system. This is different than what is usually found, with the degree of ease associated with using the system (effort expectancy) traditionally being one of the most important factor explaining behavioural intention. However, as patients were ‘free’ to choose whether they used the SMSS or not, it makes sense that their appreciation of using the system was a crucial factor. This finding suggests that the emotional experience of using a SMSS should be taken into account when designing and implementing a system to be used in healthcare.
In chapter 4 we describe the results of a study investigating the analytical performance of the creatinine device that was used throughout our studies, the StatSensor® Xpress-iTM, for both detecting current renal function with a single measurement and monitoring renal (dys)function with subsequent measurements in kidney transplant patients. Concerning single measurements, the total allowable error criterion of 6.9% was not met. Further, the average overall coefficient of variation (CV) for the StatSensor® was 10.4% using capillary whole blood results while this was < 1.5% for the central laboratory serum creatinine method. Based on these findings, we concluded that the StatSensor® at that time was not suitable for detecting kidney (dys)function of kidney transplant patients in case of single capillary blood measurements. During kidney transplant follow-up, however, creatinine values are usually interpreted by comparing subsequent measurements, reflecting a monitoring purpose in which the uncertainty of a single creatinine test results is less critical. Our results showed a reasonable correlation (R=.77) between the percentages change that were detected by the central laboratory and the StatSensor® device. A sudden increase in creatinine of >10% is of special interest, as this suggests further analysis or intensified follow-up is needed. The StatSensor® correctly identified a difference of > 10% (true positive) in 70% and a difference of ≤ 10% (true negative) in 67% of all cases (total agreement 68%). We concluded that although StatSensors’® ability to detect changes in kidney function needs improvement, it does have potential for monitoring creatinine in case StatSensor® measurements are performed in a higher frequency than laboratory creatinine analyses. This will result in a more reliable trend, as the confidence interval decreases proportionally to the square root of the number of performed measurements, given a normal distribution. As such, the chances of detecting rejection are increased and theoretically, the number of outpatient visits can be safely reduced.
Summary 179
































































































   179   180   181   182   183