INTERCHANGEABILITY OF THE I‐STAT POINT OF CARE ANALYZER WITH CENTRAL LABORATORY TESTING IN AN EMERGENCY DEPARTMENT SETTING

Abstract

Background and Significance: The i‐STAT point of care blood analyzer is a handheld device used for a variety of laboratory analyses in medical settings. Much research has been performed to evaluate its validity, but it has not been exhaustively tested in real‐world emergency department settings, despite its increasingly popular use in such settings. Methods: We retrospectively examined medical records at the Maricopa Integrated Health Systems Emergency Department to find 100 instances between February 2014 and September 2014 in which a patient had electrolyte testing performed on both the i‐STAT and in the central laboratory within a 60 minute timeframe. These data were examined using variance of means and Bland‐Altman graphing for equivalency. Results: We set the clinical equivalence threshold for each lab to be 5% of the mean normal value. That is, if the i‐STAT differed from central lab by less than 5% of the middle of the normal range (137‐145 for sodium, 5% of which is 7) then we consider them to be clinically equivalent. At this level we were unable to show clinical equivalence. In additional, all electrolytes tested showed small but significant bias between the i‐STAT and the central laboratory. Re‐examination of the data excluding all measurements more than 15 minutes apart showed similar findings. Conclusions: At this time we cannot show equivalency between the i‐STAT device and the central laboratory when used under real‐life emergency department conditions. More research is needed is to support or refute these findings.