Examining the Psychometric Properties of the Ultra-Short Version of the Oral Health Impact Profile in Australia

The Oral Health Impact Profile (OHIP) is the most widely used instrument to measure the subjective impact of oral conditions. This study reports the shortening and psychometric evaluation of an ultra-short version (OHIP-7A) from the OHIP-14 in a large national Australian population.

Cross-sectional data included 2734 participants from Australia's National Study of Adult Oral Health (NSAOH) 2017-2018. The sample was divided into training (n = 1367) and test sample (n = 1367). Exploratory statistical procedures (redundancy analysis, Ant Colony Optimisation, dimensionality analysis) used in the establishment of ultra-short versions were employed in the training sample. Confirmatory procedures involving the examination of model fit, criterion validity and reliability were employed in the test sample. The establishment of ultra-short versions from an expert opinion ('Expert-derived OHIP-7') and exploratory ('Exploratory-derived OHIP-7') perspectives were investigated.

Both Expert-derived and Exploratory-derived ultra-short versions displayed a unidimensional structure with good item performance based on network loadings. Both models displayed excellent model fit in terms of Comparative Fit Index (CFI ≥ 0.950) and Root Mean Square Error of Approximation (RMSEA ≤ 0.050), good criterion validity with variables such as self-rated dental health and good reliability (ω $>$  0.70). However, based on individual items' ability to capture 'impact' according to item content and distribution of responses across item categories, the Exploratory-derived OHIP-7 (OHIP-7A) was considered superior.

The good psychometric properties of the OHIP-7A in terms of validity and reliability allow aspects of oral health that are meaningful to patients to be captured with a small number of items. This is the first and largest study to comprehensively validate an ultra-short version of the OHIP in an Australian population.