Validity and reliability of the thirst distress scale and the short version of the xerostomia inventory for use in German patients with chronic heart failure: A multicenter cross-sectional study

Background: Thirst and xerostomia are prevalent and distressing symptoms in patients with chronic heart failure (CHF). Evaluation of interventions to alleviate these symptoms requires valid and reliable instruments. Such instruments are currently lacking for German patients with CHF. Objectives: The purpose of this study was to evaluate the structural and convergent validity, and internal consistency reliability of the German versions of the Thirst Distress Scale for Patients with Heart Failure (G-TDS-HF) and the short form of the Xerostomia Inventory (G-SXI). Methods: A cross-sectional, multicenter study was conducted involving patients with CHF. Participants completed a questionnaire containing the G-TDS-HF, G-SXI, and a visual analog scale (VAS) to indicate intensity of thirst and xerostomia. Exploratory and confirmatory factor analyses were conducted to assess structural validity. To assess internal consistency reliability, McDonald's Omega total was calculated, and Pearson<acute accent>s r was used to examine convergent validity. Results: A total of 371 patients (62.4 (+/- 14.9) years, 28.3 % female) participated in the study. Factor analysis of the G-TDS-HF revealed a two-factor structure. One factor represents symptom occurrence, and the second factor is symptom distress. Internal consistency reliability was deemed adequate, with McDonald's Omega total coefficients of 0.81. The correlation between the sum scores of the G-TDS-HF and thirst intensity (VAS) was r = 0.44 (p < 0.001). The G-SXI demonstrated a single-factor structure with a McDonald's Omega total of 0.71. The correlation between the G-SXI and xerostomia intensity (VAS) was r = 0.36 (p < 0.001). Conclusion: Results suggest that the G-TDS-HF and the G-SXI are valid and reliable instruments. Further research is warranted to assess responsiveness and test-retest reliability to strengthen the evidence.