Comparison of a Point-of-care Cholesterol Meter With a Reference Laboratory Analyzer in Companion Psittaciformes

Hypercholesterolemia is common in captive Psittaciformes. A point-of-care cholesterol analyzer would be useful to monitor hypercholesterolemia in psittacine birds. We compare a point-of-care cholesterol analyzer (PTS-Diagnostics CardioChek) with a reference laboratory analyzer (Roche Cobas c501) and provide initial assessment of precision and accuracy. A prospective method comparison study was designed to compare the CardioChek and Cobas c501 by assessment of clinical and analytical agreement using Passing-Bablock regression analysis and difference plots. Initial accuracy was assessed by running cholesterol standards, and initial precision was assessed by calculating between-run coefficient of variation on samples from selected birds. A total of 42 psittacine birds were sampled. No significant constant bias was found between the Cobas and CardioChek. However, a significant negative proportional bias was evident, suggesting that the point-of-care analyzer tended to underestimate cholesterol values. Lipemia and hemolysis had strong effects on increasing bias. Hematocrit, glucose level, and genus had no significant impact on bias, controlling for lipemia and hemolysis. Accuracy of the CardioCheck was suboptimal to that of the Cobas, but precision was good. When defining hypercholesterolemia as >8 mmol/L (309 mg/dL), the CardioChek had a sensitivity of 57% and specificity of 96%. There was neither analytical nor clinical agreement between the CardioChek and Cobas c501. Values obtained from the CardioChek cannot be used to determine or monitor hypercholesterolemia in parrots in the absence of analyzer-specific reference intervals.