Validation of the response format of the Oral Health Impact Profile.

The study investigated the validity of the response format of the Oral Health Impact Profile 49 (OHIP-49). The OHIP-49 was completed by 145 consecutive prosthodontic patients. For each OHIP item, subjects completed the standard ordinal response format (with responses given as never, hardly ever, occasionally, often, or very often, and scored from 0 to 4, respectively). Subjects also separately reported the absolute frequency of impacts for each item (numerical response format) in a personal interview. Response codes for the standard ordinal response format (0-4) and for the numerical response format were summed to give two separate OHIP summary scores. The reliability and validity of the scores generated from each response format were compared using the numerical response format as the standard. Score reliability was high and almost identical for both response formats. Score validity was also satisfactory with a high correlation of scores between response methods. There was also a moderate correlation of scores from both response methods with a single global rating of perceived oral health. These data support the validity of the standard ordinal response format of the OHIP and suggest the use of the numerical response format in order to help capture impacts on oral health when they are infrequent.