Automatic analyzers simplify processes and may help improve standardization. The first automated analyzer based on mass spectrometry is available and offers a panel for monitoring cyclosporin A, tacrolimus, sirolimus, and everolimus. Method comparisons and evaluation tests are presented to verify the capability of the Cascadion system for use in a clinical laboratory.
Sample preparation and measurements were performed using the Cascadion clinical analyzer. More than 1000 measurement values of patient samples were compared with an in vitro diagnostic (IVD)-certified assay run on a liquid chromatography tandem mass spectrometry (LC-MS/MS) instrument. Precision and accuracy were determined using commercial quality control and external quality assessment (EQA) samples.
A good correlation between the two instruments was observed (Pearson’s correlation r = 0.956–0.996). Deming regression revealed 95% confidence intervals of slopes and intercepts covering the values 1 and 0, for sirolimus and everolimus, respectively, indicating equivalence of both measuring systems. However, for cyclosporin A, a bias was observed and confirmed using a Bland-Altman plot (-9.1%). Measurement repeatability and intermediate measurement precision were appropriate showing coefficients of variation of 0.9-6.1% and 2.0-5.3%, respectively. Accuracy according to internal quality controls was 85-111% and 81-100% in the EQA samples of RfB (Reference Institute of Bioanalytics) and LGC (Laboratory of the Government Chemist), respectively. High robustness was found with regard to the linearity of the calibration lines (linear regression coefficient r2 > 0.99). Carry-over was negligible (0.1%).
The Cascadion automatic analyzer produced convincing results in the measurement of patient, control, and EQA samples. The throughput was sufficient for routine use. Overall, it can be used as an alternative to open LC-MS/MS instruments for immunosuppressant monitoring, simplifying processes without the need for specially trained personnel.