Accuracy of the stable‐side wellness ready test compared with laboratory insulin concentrations in UK equids

Summary Background The Wellness Ready Test (WRT) is a stable‐side lateral‐flow assay for blood insulin concentrations in equids. The assay has been validated and compared with a radioimmunoassay used commercially in the United States. A method comparison with insulin assays commonly used in the United Kingdom would facilitate WRT clinical application. Objectives To compare WRT insulin analysis with the Immulite 2000XPI chemiluminescent immunoassay (ICLIA) and the Tosoh immunofluorescent assay (TIFA). Study Design Method comparison. Methods Basal insulin concentrations were analysed from clinical cases for routine diagnosis (ICLIA). Residual blood was used for comparative analysis using the WRT and TIFA. To account for the WRT's restricted range (20–99.9 μIU/mL), data were reformatted into two datasets. Continuous data were analysed using Lin's concordance correlation coefficients (CCC) and Spearman's rank correlation coefficient. Clinically relevant WRT cut‐offs for laminitis risk were derived by receiver operating characteristic (ROC) analysis compared with the reference method (TIFA). Continuous insulin data were categorised using method‐specific laminitis risk cut‐offs. Ordinal kappa coefficients (linear and quadratic) are reported for the inter‐method agreement of categorical insulin data. Results Fifty‐nine samples were analysed. WRT demonstrates good discrimination between low‐risk (TIFA <21.6 μIU/mL) and medium‐/high‐risk cases, area under the ROC curve (AUC) = 0.94 (95% CI 0.89–1.00) and high‐risk (TIFA >45.2 μIU/mL) cases AUC = 0.98 (95% CI 0.96–1.00). Derived cut‐offs for WRT basal insulin values were low risk <25.8 μIU/mL, high risk >49.1 μIU/mL. Cohen's Ordinal kappa coefficient for laminitis risk categories for WRT and TIFA was very good (quadratic kappa = 0.88 (95% CI 0.81–0.93)). Concordance was poor and the WRT showed fixed and proportional bias. Main Limitations Limited data from one hospital and a restricted WRT readable range. Conclusions As a point‐of‐care screening tool, the WRT effectively classifies laminitis risk compared to TIFA reference values, although it is not numerically interchangeable with UK laboratory methods.