Table 3.

Cutoff values recommended by the manufacturer and calculated optimal cutoff giving the highest Youden index for all four testsa

TestCutoff (U/ml) (Youden index)
RecommendedOptimal
Enzygnost II IgG10 (90.0)11.5 (91.7)
Enzygnost II IgA10 (42.0)6.5 (61.4)
Pyloriset IgG300 (68.4)210 (82.1)
Pyloriset IgA250 (22.2)130 (69.1)
  • a The Youden Index is defined as follows: (sensitivity + specificity) − 1, so that the highest Youden index has the lowest number of misclassified results. Sensitivities and specificities for the calculated optimal cutoffs are as follows: Enzygnost II IgG, 93.8 and 97.8%; Enzygnost II IgA, 64.6 and 96.7%; Pyloriset IgG, 85.4 and 95.7%; Pyloriset IgA, 84.1 and 84.9%.