Comparative performance of automated immunoassay systems for procalcitonin measurement: Vidas B.R.A.H.M.S vs. Maglumi

Objectives Sepsis remains a major cause of morbidity and mortality, and its elusive symptoms present a diagnostic challenge. The current gold standard, blood culture, has limited sensitivity. Procalcitonin (PCT) has emerged as a promising biomarker for sepsis diagnosis. This study aimed to compare two automated immunoassay systems, Vidas B.R.A.H.M.S PCT ELFA and Maglumi PCT CLIA, for PCT measurement. Methods PCT levels in 93 patient samples from various hospital departments were analyzed using Vidas B.R.A.H.M.S PCT ELFA (Biomerieux, France) and Maglumi PCT CLIA (SnibeCo.,China). Bland-Altman analysis assessed mean differences and Cohen’s kappa was used to evaluate concordance at clinically significant thresholds (0.05, 0.5, 2.0, and 10 ng/mL) based on Landis and Koch’s classification. Passing-Bablok regression was performed to assess linearity and to detect proportional and constant bias between methods. Results Bland-Altman analysis demonstrated a mean bias of −0.60 ng/mL with 95 % limits of agreement (LoA): −4.60 to 3.40 ng/mL, indicating minor but consistent differences. The Maglumi system exhibited stable variability at lower concentrations and proportional variability at higher concentrations. Cohen’s kappa showed moderate concordance (κ=0.768, p<0.001). Passing-Bablok regression yielded y =0.846 x p=0.0289 [95 % CI: slope 0.7828–0.9300, intercept 0.01773–0.05719], confirming proportional and constant bias. Subgroup regression showed R 2 =0.946 for ≤5 ng/mL and R 2 =0.892 for >5 ng/mL, highlighting reduced interchangeability at higher PCT levels. Conclusions The findings indicate that both automated immunoassay systems exhibit acceptable agreement at lower PCT concentrations. These findings highlight the importance of evaluating method-specific performance characteristics when selecting diagnostic tools for sepsis management.