Validation of a patient-reported outcome measure for fatigue in patients receiving hemodialysis: the SONG-HD Fatigue instrument

Background: Fatigue is a very common and debilitating symptom and identified by patients as a critically important core outcome to be included in all trials involving patients receiving hemodialysis. A valid, standardized measure for fatigue is needed to yield meaningful and relevant evidence about this outcome. Objectives: To validate a core patient-reported outcome measure (PROM) for fatigue in hemodialysis. Design: A longitudinal cohort study was conducted to assess the validity and reliability of a new fatigue measure (SONG-HD Fatigue).Eligible and consenting patients completed the measure at three time points: baseline, a week later and twelve days following the second time point. Cronbach’s α and Intraclass correlation coefficient were calculated to assess internal consistency and Spearman’s rho was used to assess convergent validity. Confirmatory factor analysis was also conducted.Setting: Hemodialysis units in the United Kingdom, Australia and Romania participated in this study.Participants: Adult patients aged 18 years and over, English-Speaking, and receiving maintenance hemodialysis were eligible to participate.Measurements: SONG-HD Fatigue, visual analogue scale for fatigue, 12-Item Short Form survey, Functional Assessment of Chronic Illness Therapy-Fatigue were used.Results: In total, 485 participants completed the study across the United Kingdom, Australia, and Romania. Psychometric assessment demonstrated that the SONG-HD Fatigue is internally consistent (Cronbach’s α =0.81- 0.86) and stable over a one-week period (Intraclass correlation coefficient =0.68-74). The measure demonstrated convergence with Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F) and had moderate correlations with other measures that assessed related but not the same concept (12-Item Short Form Survey and Visual Analogue Scale). Confirmatory factor analysis supported the one-factor model. Conclusions: The SONG-HD Fatigue appears to be a reliable and valid measure to be used in trials involving patients receiving hemodialysis. </div