Evaluation of a research use only luminex based assay for measurement of procalcitonin in serum samples

Research use only (RUO) assays do not undergo a validation process similar to test kits used for clinical purposes. Several studies have suggested that RUO assays need to be validated prior to use in any research studies. We evaluated a research use only Luminex platform based assay for measuring serum procalcitonin levels (Bio-Plex Pro^TM Human Acute Phase Multiplex Assay, Bio-Rad Laboratories, Hercules, CA) for comparability with an FDA cleared assay for procalcitonin (VIDAS B.R.A.H.M.S. PCT Assay, bioMérieux, Durham, NC). We tested 1,072 serum samples collected from patients with suspected sepsis in an intensive care unit setting for the comparison. There was poor correlation of the luminex based assay (r=0.081) with the VIDAS PCT Assay in the clinically relevant measurement range (<10 ng/mL). Additionally the Bio-Plex assay showed poor precision. Mass-spectrometry analysis of material eluted from PCT beads did not reveal any identifiable procalcitonin. The results show that research use only assays need to be validated to determine their suitability for research studies.