Conclusion
We found random variation between the PETIA and ELISA test that could affect performance in a clinical context, but only to a lesser extent in a research context. The new clinical biochemistry assay for HA determination will allow for large studies of the clinical utility of HA.
Methods
HA was measured by a particle-enhanced turbidimetric immunoassay (PETIA) and enzyme-linked immunosorbent assay (ELISA) in a 40-sample dilution series and 39 intensive care unit (ICU) patients. Agreement was assessed with Bland-Altman's method.
Results
In the ICU patients, the median HA concentration was 159.0 ng/ml (interquartile range (IQR) 117.5-362.5 ng/ml) with ELISA and 157.5 ng/ml (IQR 92.5-359.6 ng/ml) with PETIA. The mean difference was 12.88 ng/ml (95% CI, -4.3 to 30.1 ng/ml, P = 0.14) and the 95% limits of agreement were -91.17 to 116.9 ng/ml. In the dilution series, the mean difference was -59.26 ng/ml (95% CI, -74.68 to 43.84 ng/ml, P < 0.0001) and the 95% limits of agreement were 35.23 to -153.8 ng/ml.