Evaluation of the DrugCheck 9 on-site immunoassay test cup according to a standard method validation protocol

Improvements have been made in recent years in on-site or point-of-care (POC) immunoassay testing devices. We evaluated the DrugCheck 9 cup, a new qualitative visually read, competitive binding, immunoassay cup that measures nine analytes. The study was performed according to the recent National Laboratory Certification Program (NLCP) guidelines for validating a laboratory-based immunoassay. The study included a linearity challenge with 5 replicates at concentrations 0, 25%, 50%, 75%, 100%, 125%, and 150% of the cutoff and also determination of the limit of detection. Interference (specificity) studies were included to evaluate the cross-reactivity of common structural analogues or others purported to interfere with the assay. The ability to differentiate positive and negative samples was evaluated by positive and negative quality control specimens and also parallel comparisons of laboratory verified positive and negative donor specimens previously analyzed by immunoassay and gas chromatography-mass spectrometry. The results indicated a high degree of correlation (97.6%) with the laboratory immunoassay and a high degree of specificity and sensitivity with extended linearity below the cutoff.