Development and psychometric evaluation of the Thirst Distress Scale for patients with heart failure

Background: Patients with heart failure can experience thirst distress. However, there is no instrument to measure this in patients with heart failure. The aim of the present study was to develop the Thirst Distress Scale for patients with Heart Failure (TDS-HF) and to evaluate psychometric properties of the scale. Methods and results: The TDS-HF was developed to measure thirst distress in patients with heart failure. Face and content validity was confirmed using expert panels including patients and healthcare professionals. Data on the TDS-HF was collected from patients with heart failure at outpatient heart failure clinics and hospitals in Sweden, the Netherlands and Japan. Psychometric properties were evaluated using data from 256 heart failure patients (age 7211 years). Concurrent validity of the scale was assessed using a thirst intensity visual analogue scale. Patients did not have any difficulties answering the questions, and time taken to answer the questions was about five minutes. Factor analysis of the scale showed one factor. After psychometric testing, one item was deleted. For the eight item TDS-HF, a single factor explained 61% of the variance and Cronbach's alpha was 0.90. The eight item TDS-HF was significantly associated with the thirst intensity score (r=0.55, p<0.001). Regarding test-retest reliability, the intraclass correlation coefficient was 0.88, and the weighted kappa values ranged from 0.29-0.60. Conclusion: The eight-item TDS-HF is valid and reliable for measuring thirst distress in patients with heart failure.