Factor analysis of two versions of the Oral Impacts on Daily Performance scale.

The aim of this study was to explore the factorial structure and agreement of two scoring versions of the Oral Impacts on Daily Performance (OIDP) scale, and to compare the fit of the originally proposed factorial structure, as opposed to an alternative model. Exploratory factor analyses (EFA) were conducted to explore the dimensional structure of the OIDP on a convenience sample of 200 adults (S1). Confirmatory factor analyses (CFA) were performed on a random sample of 720 adults (S2). The Cronbach's alpha coefficients for the total and frequency versions of the OIDP scale were, respectively, 0.81 and 0.70 for S1, and 0.82 and 0.79 for S2, with a quadratic Kappa κ = 0.83 (95% CI: 0.75-0.89) in S1 and κ = 0.92 (95% CI: 0.89-0.94) in S2. Exploratory factor analyses showed one factor for the total version and three factors (non-interpretable) for the frequency version. Confirmatory factor analyses showed that the frequency version for the one-factor model (Model 1) had the best fit [Root Mean Square Error of Approximation (RMSEA) = 0.04; Comparative Fit Index (CFI) = 0.98; Tucker-Lewis index (TLI) = 0.97, χ(2) P-value < 0.01]. The one-factor model was not significantly different from the original three-factor model. These findings suggest that the scale captures only one overall quality of life dimension, and that the frequency version was the most parsimonious model of the OIDP scale.