Validity and reliability of the Spanish version of the Dental Impact on Daily Living (Sp-DIDL) questionnaire in a Spanish population: a cross-sectional study.

BACKGROUND: Oral health has an impact on the patient's quality of life. This study aimed to translate, culturally adapt, and comprehensively validate the Dental Impact on Daily Living (DIDL) index for use among Spanish-speaking adults, encompassing the assessment of its reliability and construct validity. A secondary aim was to correlate the Sp-DIDL with demographic data, caries, periodontal attachment loss, and the use of prosthesis.METHODS: The original DIDL was translated and adapted into Spanish following international guidelines. A pilot test was done with 20 patients to assess comprehension and validity. Psychometric properties were evaluated in a cross-sectional study using a convenience sample of 125 adults (mean age 49.3 years) recruited from the Dental Hospital of the University of Barcelona. Internal consistency was analysed with Cronbach's alpha. Intraclass Correlation Coefficient (ICC) was used to assess the test-retest reliability of the clinical measures (DMF index and periodontal attachment loss). Confirmatory Factor Analysis (CFA) and Known-Groups Validity were used to evaluate construct validity. The associations with demographic data, the Decayed-Missing-Filled (DMF) index, periodontal loss, and the use of prosthesis were assessed using one-way ANOVA, Student t-tests, Pearson's correlation, and multiple linear regression analysis.RESULTS: The final version of the Sp-DIDL was approved after testing on 20 patients (Cronbach's α = 0.919). In the validation stage, all Cronbach α values were > 0.90, indicating excellent internal consistency. The 5 factors had an explained variance over 0.40 (0.51 to 0.78). The mean DIDL score was - 1.08 (standard deviation (SD) = 1.82). Overall, the Sp-DIDL score showed a negative correlation with age (r = -0.535, p < 0.001) but was not associated with gender (p = 0.235). Patients with elementary studies or less had lower Sp-DIDL scores (p < 0.05). DMF was negatively correlated with Sp-DIDL (r = -0.318; p < 0.001). Patients with dental prostheses had lower Sp-DIDL scores (p < 0.05). The multiple lineal regression model only included age as a predictor of Sp-DIDL score (B = -0.049; p < 0.001).CONCLUSIONS: The DIDL questionnaire was validated in a Spanish population. This Spanish version of the DIDL proved valid and reliable for measuring the impact of oral health on patient quality of life. The Sp-DIDL was negatively correlated with age: the older the patient, the greater the impact of oral health status upon quality of life.