Validity of two oral health-related quality of life measures

OBJECTIVES: To assess the validity of the Oral Impacts on Daily Performance (OIDP) and the short form of the Oral Health Impact Profile (OHIP 14) in the UK. SETTING: Primary care department at a UK dental hospital. SAMPLE: Consecutive patients. METHOD: Cross-sectional comparison of impacts using OIDP and OHIP 14 against clinical findings, Global Oral Health Ratings and pain. RESULTS: A total of 179 patients participated (83.2% response rate). OIDP had weak face validity because it contained contingency questions. Both instruments were developed from the same theoretical model and appeared to have reasonable content validity. In regression analyses, the number of impacts detected by each measure and the total score using OHIP 14 were related to the presence of oral disease and inversely related to age. No suitable transformation could be found to allow regression analysis of OIDP total scores. OHIP 14 correlated more closely with Global Oral Health Ratings but both measures correlated similarly to the experience of pain (0.43 < r < 0.47). The correlation between OHIP and OIDP scores was +0.78. The use of a simple additive method for calculating the total OHIP 14 score did not compromise its validity. CONCLUSION: Both instruments have some validity as measures of Oral Health-Related Quality of Life (OHRQoL) among dental hospital patients. The superior face, criterion and convergent validity and greater amenability to analysis of OHIP 14 render it more suitable for questionnaire-based research and for comparing groups. The additive method may be used to calculate the total score for OHIP 14.