UTILITY OF ROC CURVES IN THE APPLICATION OF A DIAGNOSTIC-TEST

The aim of this study was to obtain the cut point to determine an indi vidual's seronegativity with respect to measles using commercial reage nts. To determine the test sensitivity, the serum of 22 individuals 21 years of age or older, and a positive history of measles (positive co ntrol group), was studied. For specificity, the serum of 22 children 1 5 to 24 months old, and no measles vaccination record nor positive his tory of measles (negative control group), was analyzed. The antibodies titer determination for both groups was done using the ELISA techniqu e and the Brunell method, subsequently, as well as a ROC curve (Receiv ed Operating Curve). When the Brunell method was used, the cut points were 0.4090 (sensitivity 1.0 and specificity 0.95) and 0.5042 (sensiti vity 0.95 and specificity 1.0). When a ROC curve was done the cut poin t was 0.4500, with a sensitivity and specificity of 100 per cent. It w as also concluded that the latter is the best method to obtain this cu t point, because it does not establish arbitrary values when the data distribution does not follow a normal pattern.