Letter to the Editor Proper Estimation of Sensitivity and Specificity

摘要

I write to express concern about the diagnostic accuracy statements of Eda et. al. concerning a new Johne's disease enzyme-linked immunosorbent assay (ELISA). The diagnostic sensitivity of this new ELISA for bovine paratuberculosis, reported to be 100%, was based on only 64 (according to the Materials and Methods) or 51 (according to the Results) Mycobacterium paratuberculosis fecal culture-positive cattle. Fecal culture-positive cattle with fewer than five colonies on culture were discarded from the dataset, which might explain the different numbers in the Materials and Methods and Results, but this is unclear in the paper. While the authors speculate that these very low fecal shedders of M. paratuberculosis "might arise from pass-through bacilli," there is no legitimate basis for excluding these cattle from sensitivity analysis. No other reports on ELISA sensitivity for bovine paratuberculosis have done this. There is no way to ascertain if these cattle were truly infected or if such fecal culture results represented "pass-through" (i.e., the cows were not infected and M. paratuberculosis from the environment was simply in transit through the gastrointestinal tract).