1991 Volume 1 Issue 2 Pages 11-15
For the purpose of predicting prognosis after extrusion of the ventilation tube (VT), discriminant analysis was done on 78 ears with secretory otitis media (SOM) treated by insertion of VT. 78 ears were divided into two groups (good prognosis, poor prognosis) based on the clinical course after the extrusion of VT. Discriminant function was obtained by studying five following variables; age at which SOM was diagnosed, age at which a VT was inserted, age at which a VT was extruded, middle ear air volume measured by tympanometry 6 months after the insertion of VT and duration of ventilation by VT. In the study using a single variable, the lowest probability of misclassification was 0.281, which was obtained by using the middle ear air volume as the variable. This indicates that the middle ear air volume is the most useful prognostic indicator among the five variables. In the study of model with two variables, the lowest probability of misclassification was 0.248, which was obtained by the combination of the middle ear air volume and duration of ventilation. The results of this study suggest that the predication of prognosis of SOM is theoretically possible with 75% accurracy by using the discriminant function.
