Interchangeability, accuracy, and precision of a handheld blood lactate analyzer across low to high exercise intensities

Abstract Purpose To assess: (1) within-brand differences and interchangeability of the TaiDoc TD-4289 analyzer, by evaluating the measured blood lactate concentrations across ten units of this analyzer; (2) the accuracy and precision of the analyzer using newly developed strips that present lactate concentrations on a different scale. Methods Venous blood samples were taken at relevant exercise intensities. The blood lactate concentration was measured simultaneously with different units of TaiDoc TD-4289. In the first test, 400 measurements of blood lactate using original strips of code 546 were performed (four intensities times 10 measurement series times 10 units). The within-brand analysis used a modified mean excluding the minimum, maximum, and considered value in each measurement series as reference. In the second test, 64 measurements of blood lactate using newly developed strips of code 335 were performed (eight measurements series times eight units). The measurements were compared to a reference analyzer (YSI Sport 1500) to determine the accuracy and precision when using the code 335 strips. Results Within-brand differences were non-significant; all 10 units were within an absolute mean relative difference to the modified mean of 1.8%. When using code 335 strips, the mean relative difference to the reference analyzer was 45% and the residual standard error was 0.097 mM. Conclusion The TaiDoc TD-4289 analyzer demonstrated high degree of within-brand interchangeability. Using the new code 335 strips, its accuracy was comparable to other established analyzers, while the precision was considerably better than what we have previously found with other commonly used handheld lactate analyzers.