Rasch validation of the oral health impact profile for temporomandibular disorders.

OBJECTIVES: This study examined the metric properties of the Oral Health Impact Profile for Temporomandibular Disorders (OHIP-TMD) using Factor/Rasch analyses and created a short-form version of the measure. SUBJECTS AND METHODS: Aggregated OHIP-TMD data were obtained from a cross-sectional study involving 844 TMD patients with diagnostic criteria for TMDs defined conditions. The dimensionality of the OHIP-TMD was first evaluated with exploratory factor analysis. An eigenvalue >1.0 and oblique oblimin rotation were applied for extracting the factors. Rasch analysis was subsequently performed on the primary dimension using the ConQuest software. RESULTS: Multi-dimensionality of the OHIP-TMD was observed with the primary dimension comprising ten items. Adequate fit to the Rasch model was noted after deleting item 8 with infit/outfit mean-square values ranging from 0.75 to 1.40 logits. Item difficulty ranged from -0.75 to 1.05 logits, while participants' ability to respond varied from -4.55 to 5.19 logits. The respondent spread was slightly skewed and satisfactory item-response targeting was present. CONCLUSIONS: The 22-item OHIP-TMD demonstrated multi-dimensionality with the primary dimension consisting of nine reliable items with adequate fit to the Rasch model. The 9-item short-form version of the OHIP-TMD (SOHIP-TMD) is a promising tool for evaluating OHRQoL.