Utilidad de las curvas de sensibilidad y especificidad conjunta en la aplicación de una prueba de diagnóstico

The aim of this study was to obtain the cut point to determine an individual's seronegativity with respect to tneasles using commercial reagents. To determine the test sensitiviiy, the serum of 22 individuals 21 years of age or older, and a positive history of measles (positive control group), was studied. For specificity, the serum of 22 children 15 to 24 months old, and no measles vaccination record nor positive history of measles (negative control group), was analyzed. The antibodies titer determination for both groups was done using the ELISA technique and the Brunell method, subsequently, as well as a ROC cuwe (Received Operating Cuwe). When the Brunell method was used, the cut points were 0.4090 (sensitivity 1.0 and specificity 0.95) and 0.5042 (sensitivity 0.95 and specificity 1.0). When a ROC cuwe was done the cut point was 0.4500, with a sensitivity and specijicity of 100 per cent. It was also concluded that the latter is the best rnethod to obtain this cut point, because it does not establish arbitrary values when the data distribution does not follow a normal pattern.