Translation and validation of a Spanish version of the xerostomia inventory

Objective The aim of this study was to validate a Spanish cross-cultural adaptation of the xerostomia inventory (XI). Materials and methods The original English version of XI was translated into Spanish, cross-culturally adapted and field tested. The Spanish version of XI (XI-Sp) was tested with a sample of 41 patients with xerostomia. The reliability of the XI-Sp was determined through internal consistency and test–retest methods. The construct validity of XI-Sp was determined by means of correlation between XI-Sp scores and salivary flow measurements. Results Overall XI-Sp scores were 40.8 (SD = 10) for the first application and 40.2 (SD = 9.5) for the second. Cronbach's alpha value for the XI-Sp was 0.89 and 0.87, respectively, while interitem correlation averages were r = 0.44 and r = 0.39 for each application. Interitem correlation and corrected total was rc≥0.30. The test–retest intraclass correlation coefficient value for the XI-Sp score was 0.59 and 0.91. Convergent validity for construct validity correlation with salivary flow showed a medium effect size (r2 = 0.10) for the first application but did not make a statistically significant prediction for the second (r2 = 0.7). Conclusions This study provides evidence concerning the reliability of the XI-Sp, showing that it may be a useful tool for Spanish-speaking xerostomia patients for both clinical and epidemiologic research.