Author : Latifah Anandari*, Astuti Giantini
Aim: Procalcitonin is a calcitonin prohormone, its elevation used as one of many sepsis parameters. Procalcitonin Easy Diagnosis is an immunochromatographic cassette, its color intensity shift measured with imaging technology to determine procalcitonin level. Brahms Kryptor is an immunoassay that uses TRACE (Time Resolved Amplified Cryptate Emission) method. This study aims to determine agreement between the two method of measurement. Method: Test for comparison of two method is used. Precision test performed using control cassette with fixed level (25 ng/mL), run 10 times consecutively. Precision test using patient samples performed at low level (< 0.5 ng/mL), high ( > 0.5 ng/mL), and very high ( > 2 ng/mL), each runs 5 times consecutively. Subject of the study settled at 40, based on minimum sample requirement for comparison test. Correlation test and Bland-Altman plot used to analyze data set. P value < 0.05 is considered significant with 95% confidence interval. Results: Coefficient of variant (CV) obtained from control cassette is 2.528 %. Result for CV in low level (0.13 ng/mL), high 0.67 ng/mL), and very high (2.34 ng/mL) are 13.07%, 21.81%, and 13.77% respectively. Spearman correlation resulted r = 0.898 ( p < 0.05). Bland-Altman analysis performed in four groups of data set, < 0.5 ng/mL, > 0.5 ng/mL, > 2 ng/mL, and > 10 ng/mL. In the first group, there are two result outside limits of agreement. Agreement between the two methods is 95 %. Discussion: There is a significant difference between precision test using control cassette and patient samples. Control materials that fit standard requirement is needed. There is a good correlation between two methods. The two value outside limits of agreement in the first group are higher than > 0.2 ng/mL mean, showing a decreased agreement in higher procalcitonin level. Conclusion: There are good correlation and agreement between the two methods. It is advised to provide control material that fit control material requirements. Key words: Procalcitonin, immunochromatographic assay, TRACE, comparison test.
Dr. Arend L Mapanawang, Sp.PD, FINASIM, PhD