Psychometric approach of the revised Illness Perception Questionnaire for Oral Health (IPQ-R-OH) in patients with periodontal disease.

BACKGROUND: The purpose of this study was to evaluate the psychometric properties of the validated Spanish version of the Illness Perception Questionnaire Revised for Oral Health (IPQ-R-OH) in patients with periodontal disease.

METHODS: We used the IPQ-R for Oral Health (IPQ-R-OH), a self-reported 36-item scale with. This study was carried out using data from 517 patients with periodontal disease attending the dental clinic at the Universidad Cooperativa de Colombia, Pasto, Colombia. A three parameter logistic model (3PL) for polytomous response was calculated to evaluate a model of individuals' responses. The McDonald's Omega (Ω ≥ 0.60) coefficient and composite reliability were used to determine the internal consistency. Confirmatory factor analysis (CFA) was conducted to examine the fit of the hypothesized seven-factor model, and the configural invariance was tested to estimate the structure in each sex group.

RESULTS: The slope, location and guessing parameters determined reasonable accurate items according to item response theory analysis. The internal consistency coefficients of each factor ranged from 0.62-0.93 (McDonald's Omega) and 0.66-0.87 (composite reliability). Confirmatory factor analysis indicated a seven-factor model (χ2 S-B  = 2572.165; χ2 S-B /(573) = 4.489, p < 0.01; NNFI = 0.950; CFI = 0.950; RMSEA = 0.055 (90% CI [0.052 - 0.059]); SRMR = 0.080 and AIC = 1426.165. The seven-factors loaded similarly to the original IPQ-R scale. Multigroup CFA analysis results supported factor invariance across the sex groups.

CONCLUSION: These findings suggest that the IPQ-R-OH has adequate reliability and construct factorial validity; therefore, it could be a valuable instrument in screening illness perceptions in patients with periodontal disease. This article is protected by copyright. All rights reserved.