On the severity of impacts captured by the dimensions of the Oral Health Impact Profile

The Oral Health Impact Profile (OHIP), containing seven dimensions, is based on a hierarchical model. Therefore, one could argue that events described by dimensions higher in the hierarchy are judged as having a more severe impact on quality of life than events described by dimensions lower in the hierarchy. The aim of this study was to test this assumption and to assess the relative severity of impact on daily life with which each dimension is judged relative to all other dimensions. The subjects were psychology freshmen. Subjects' judgments were assessed using the method of direct ranking and the method of paired comparison. The results showed differences between dimensions, with Handicap and Psychological disability being regarded as having the most severe impact on daily life. The results demonstrated the tenability of Locker's hierarchical model as the foundation of the OHIP, in that subjects rank the dimensions in a similar order of severity as intended by this model. It is suggested that the difference of the severity of impact should be compensated for, either by including subscale weights or by increasing the number of items of subscales where the impact on Quality of Life (QoL) is judged as being more severe.