Supplementary Material for: Validation of the Arabic version of the S3-non-invasive ventilation (S3-NIV) questionnaire in chronic respiratory disease

Background Non-invasive ventilation (NIV) requires ongoing monitoring to ensure optimal therapeutic efficacy. The S3-non-invasive ventilation (S3-NIV) questionnaire was recently developed as a brief, repeatable, self-administered tool for the routine clinical evaluation of patients on long-term home NIV. This study aimed to produce an Arabic translation and cultural adaptation of the S3-NIV questionnaire and to assess its psychometric properties. Methods This was a descriptive, cross-sectional study involving patients with stable chronic respiratory disease treated with long-term home NIV. The Arabic version of the S3-NIV questionnaire was developed from the original French version through a standardized translation and back-translation process. The resulting instrument was evaluated for reliability and construct validity. Results A total of 150 patients were enrolled. The Arabic S3-NIV questionnaire demonstrated good internal consistency for the total score (Cronbach’s alpha = 0.76; 95% CI: 0.69–0.83) and for the "respiratory symptoms" domain (Cronbach’s alpha = 0.793; 95% CI: 0.728–0.858). The "sleep and side effects" domain showed lower reliability (Cronbach’s alpha = 0.573; 95% CI: 0.266–0.880). Both the total score and the two subscale scores showed weak negative correlations with the Epworth Sleepiness Scale (ESS), modified Medical Research Council (mMRC) scale, pain visual analogue scale (VAS), and fatigue VAS. Exploratory factor analysis (EFA) explained 54.6% of the total variance, supporting the internal structure of the Arabic version. Conclusion The Arabic version of the S3-NIV questionnaire demonstrates acceptable reliability and construct validity, particularly for the assessment of respiratory symptoms. It is a suitable tool for routine clinical use in Arabic-speaking patients receiving home NIV, although further refinement of the "sleep and side effects" subscale is recommended.