Validity and reliability of the Slovenian translation of the questionnaire on swallowing disorders in head and neck cancer patients

Swallowing disorders (dysphagia) are a common consequence of head and neck cancer and its treatment. Swallowing and feeding are essential for survival but they also play an important role in a person's social life and enjoyment, therefore problems in this area affect quality of life. The quality of life should be a factor taken into account when planning, implementing and adapting the rehabilitation of dysphagia. Therefore, it is important to consider the patient's subjective assessment of dysphagia and how it impacts their quality of life, instead of assessing dysphagia with only objective diagnostic tools. For this reason, a patient-reported questionnaire on the impact of dysphagia on quality of life, The M.D. Anderson Dysphagia Inventory (MDADI), was developed specifically for head and neck cancer patients and has been, so far, translated and validated into 15 languages. In this master thesis we translated the original MDADI questionnaire into Slovenian and tested its validity and reliability in the Slovenian clinical setting. The study included 71 head and neck cancer patients (clinical group) and 41 asymptomatic individuals (control group) who all completed the Slovenian translation of the MDADI questionnaire. We found a statistically significant difference between the results of the clinical and control group, with the participants in the clinical group having a significantly lower score, indicating a lower quality of life. The content validity was confirmed by three experts and construct validity was confirmed by exploratory factor analysis. The reliability of the questionnaire was tested with Cronbach's alpha coefficient, which was 0,970 for the total score (0,867 to 0,967 for individual subscales), indicating a high to excellent level of reliability. We tested the correlations between the subscales and found high to very high correlations. We also investigated the presence of ceiling and floor effect for each subscale and found the ceiling effect present for all subscales in both groups. We conclude that the Slovenian translation of the MDADI questionnaire is a reliable and valid instrument for use in the Slovenian clinical setting