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Solomon has misinterpreted the column head "Any Positive Band" in our Table 2 as meaning a cut point in the test indicating a positive result when any 1 band is reactive. Receiver operating characteristic curves are calculated across all possible cut points; hence, the term any refers to all possible cut points (0, 1, 2, or 3... positive bands) among any of the measurable immunoblot bands, as opposed to all potential cut points of 3 specific bands (0, 1,2, or 3 positive bands). The ROC curve area is independent of the chosen cut point and, hence, does not change depending on the number of reactive bands considered to indicate a positive result. We agree that the test improves when the number of bands in the test is less restrictive. The appropriate cut point is that which results in the greatest sensitivity and specificity.
Although several statistical programs will easily calculate
Sivak SL, Aguero-Rosenfeld ME, Nowakowski J, Nadleman RB, Wormser GP. Analysis of ROC Curves Applied to the Diagnosis of Lyme Disease-Reply. Arch Intern Med. 1997;157(11):1267. doi:10.1001/archinte.1997.00440320176020