Validity and reliability of the Greek version of the xerostomia questionnaire in head and neck cancer patients.

Purpose: Xerostomia after radiation therapy for head and neck (H&N) cancer has serious effects on patients' quality of life. The purpose of this study was to validate the Greek version of the self-reported eight-item xerostomia questionnaire (XQ) in patients treated with radiotherapy for H&N cancer.

Methods: The XQ was translated into Greek and administered to 100 XQ patients. An exploratory factor analysis was performed. Reliability measures were calculated. Several types of validity were evaluated. The observer-rated scoring system was also used.

Results: The mean XQ value was 41.92 (SD 22.71). Factor analysis revealed the unidimensional nature of the questionnaire. High reliability measures (ICC, Cronbach's α, Pearson coefficients) were obtained. Patients differed statistically significantly in terms of XQ score, depending on the RTOG/EORTC classification.

Conclusion: The Greek version of XQ is valid and reliable. Its score is well related to observer's findings and it can be used to evaluate the impact of radiation therapy on the subjective feeling of xerostomia.