Comparison of enzyme-linked fluorescent assay and electrochemiluminescence immune assay in procalcitonin measurement

Background Procalcitonin (PCT) measurement is required for intensive care patients with systemic inflammation symptoms, early diagnosis of possible infections, and evaluation of sepsis severity and prognosis. Objectives We aimed to determine the analytical performance of PCT measurement in a Roche Modular E170 (ECLIA) analyzer and compare the performance with VIDAS (BRAHMS/ELFA) analyzer findings. Material and methods Within-day and between-day precision value, linearity was determined, and two methods were compared with regression and Bland–Altman analysis. Results Both ECLIA and ELFA assays indicated excellent precision, where within-day precision varied between 1.18% and 3.97% CV, and between-day precision varied between 1.77% and 3.93% CV. The ECLIA method was linear up to 62.15 ng/mL. The arithmetic mean was 6.02 ng/mL with the ECLIA method and 8.02 ng/mL with the ELFA method. The correlation coefficient was r=0.996 and p=0.001. The correlation was linear between the two methods. Regression equation was found y=0.78x − 0.23. The Bland–Altman figure was revealed the difference between the methods was specifically in lower concentrations (<0.15 ng/mL). Conclusions Both methods show good precision and correlation. It was determined that the difference between methods was significant, especially at <0.15 ng/mL concentration.