Validation and method comparison for a point-of-care lateral flow assay measuring equine whole blood insulin concentrations.

The study explores the Wellness Ready Test (WRT), a device that tests the level of insulin in horses’ blood. It compares the accuracy of WRT results to those of a recognized standard method, the radioimmunoassay (RIA). The research shows that the WRT device demonstrates reasonable accuracy, consistent results, and strong association with the RIA standard.

Study Methods

The researchers looked at the WRT’s repetition and variability in results in three areas:

• For 20 repeated measurements at each insulin level, intra-assay coefficients of variation (CVs) were calculated. This means they performed the same test multiple times on one sample, to see if the WRT provides consistent results.
• For 10 repeats across different batches (3 assay lots), they calculated inter-assay CVs. This means they performed the same test using different lots of the assay, to check if results are similar even when the testing conditions are slightly varied, demonstrating the reliability of the test.
• The researchers also checked the linearity of the WRT by comparing five measured insulin concentrations against expected concentrations.

Comparisons with Radioimmunoassay (RIA)

The WRT readings were also compared to the RIA, a standard laboratory method. The following steps were taken to this end:

• A Spearman correlation coefficient was calculated between the WRT and RIA to evaluate the degree of association between the two measures.
• Passing-Bablok regression, a statistical technique, was applied to find the relationship between the WRT and RIA. The goal was to establish an equation where WRT results can be predicted using RIA values.
• The WRT results were on average 10.4% higher than the RIA results, and researchers analyzed how the disparity varied at different diagnostic cut-off points.

Accuracy and Clinical Relevance

Moreover, the clinical efficiencies of the test in its sensitivity, specificity, and accuracy were determined using the RIA as a gold standard and the cutoff points for diagnosis of insulin dysregulation. Lastly, the total error in predictions from the WRT tool was calculated.

Results and Conclusion

The study found that the WRT tool had acceptable precision, excellent linearity, and good correlation with the RIA standard. This suggests that the WRT can be a useful tool for measuring insulin levels in horse’s blood. However, as the WRT results were slightly higher than the RIA results, it may be necessary to adjust scale when interpreting results if using the WRT test.