Comparative study of a point-of-care test and an enzyme-linked immunosorbent assay (ELISA) for infliximab levels

Abstract

Proactive therapeutic drug monitoring (TDM) is often challenged by long turnaround time when using enzyme-linked immunosorbent assays (ELISAs), especially when analyses are centralised. Point-of-care tests (POCTs) allow rapid assessments, but data on their agreement with existing in-house methodologies are scarce. To examine the agreement between a POCT by ProciseDx (San Diego, CA) and the most frequently used in-house ELISA for infliximab (IFX) quantification in Sweden. Serum samples were analysed using the in-house ELISA, Karolinska University Hospital, Stockholm, Sweden and a POCT by ProciseDx (San Diego, CA). Agreement was assessed and differences were examined. Samples from 61 inflammatory bowel disease (IBD) patients were analysed with a median IFX concentration of 7.9 μg/mL (interquartile range (IQR) 5.5–13) for the POCT and 7.9 μg/mL (IQR 5.2–12) for the ELISA (Pearson’s correlation coefficient = 0.95 (95% CI 0.92–0.97, p p 7.0 μg/mL) drug levels, Kappa statistics showed a substantial agreement (0.79). The POCT by ProciseDx (San Diego, CA) demonstrated a good agreement with the in-house ELISA, supporting its use for rapid IFX quantification.</p