B-010 Intercomparison Study of Methods between Atellica Solution® and CI® Analyzers for Sodium, Potassium, and Chloride

Background Method verification is an essential analysis routinely conducted in accredited Clinical Laboratories whenever a change of method or instrument for a specific analyte is desired. Objectives The aim of the study is to verify that the results measured by the Atellica Solution® analyzer (Siemens) and the new CI® analyzer (Siemens) for Sodium, Potassium, and Chloride are interchangeable. Methods To conduct the intercomparison study of Sodium, Potassium, and Chloride, the techniques were properly calibrated and controlled on both analyzers. For each assay, 40 patient samples were selected, covering the entire measurement range, and analyzed by both instruments. To determine the degree of agreement between the instruments, a Bland Altman analysis of mean differences and a Passing Bablok regression were performed. Statistics are expressed with their 95% confidence intervals (CI). The evaluation of results was carried out using the statistical program Method Validator. Results In both the Bland-Altman and Passing Bablok regression analyses, a slight constant systematic error was detected for all three assays, as the 95% confidence interval of the observed mean difference and the 95% confidence interval of the intercept of the regression line do not include zero. No systematic proportional differences were observed based on the slope, as the 95% confidence interval includes the value one Conclusions The small constant systematic differences found in the analyses should be re-evaluated after performing a new calibration of the methods. In none of the cases are the differences clinically significant, as they do not exceed the total error established in our quality specification. Therefore, it can be concluded that the Atellica Solution® and CI 1900® analyzers are interchangeable for Sodium, Potassium, and Chloride assays