Abstract
BACKGROUND: Assays based on multiplex immunoassay (MIA) technology have demonstrated advantages over enzyme-linked immunosorbent assay (ELISA) and radioimmunoassay (RIA). Its acceptance depends on how well it performs in comparison to older techniques. The aim is to compare the results of leptin using RIA versus MIA. METHODS: We analyzed 81 samples of umbilical cord blood of healthy term newborns by RIA and MIA. RESULTS: The concordance correlation coefficient was 0.158 (95% CI 0.10-0.21). Pearson's correlation coefficient was 0.6651 (95% CI 0.52-0.77; P < 0.0001). In the Bland-Altman plot, concordance is acceptable because most of the measurements are within a mean of ±1.96 SD. CONCLUSIONS: As shown by the Bland-Altman plot, there is concordance by both methods, but with a weak correlation.