Preferences of adults with spinal cord injury for widely used health-related quality of life and subjective well-being measures.

OBJECTIVE: To describe preferences for survey instruments on health-related quality of life (HRQOL) and subjective well-being (SWB) among adults with spinal cord injury (SCI), and compare perspectives on the instruments between the United States and the United Kingdom. DESIGN: We conducted 20 in-depth interviews. SETTING: Participants were interviewed in their homes, some in person and some via Skype. PARTICIPANTS: A convenience sample of 20 adults with SCI (10 in the US and 10 in the UK) were recruited via print and on-line advertisements. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Interviewees reviewed six instruments and rated how important it was for their medical providers to know answers to each survey. Two coders analyzed verbatim transcriptions independently using an inductive approach. Keyword-in-context (KWIC) analysis identified the most frequently used words by interviewees to discuss the merits of each instrument. RESULTS: Participants in both samples identified the Fatigue Severity Scale (FSS) as "vital" that their medical providers know about it. This was followed by the Spinal Cord Injury Independence Measure III, and a stand-alone Eudaimonic Well-Being question. The KWIC analysis showed that the most distinctive words used to discuss FSS were "fatigue" and "pain." CONCLUSIONS: Understanding what HRQOL and SWB measures are valued by adults living with SCI can lead to selection of informative instruments, which could help clinicians to complement and tailor established care and rehabilitation protocols for individual needs. Participants identified fatigue as a significant issue, and the FSS as a vitally important instrument to share with medical providers.

Development and Psychometric Evaluation of a Fatigability Index for Full-Time Wheelchair Users With Spinal Cord Injury.

OBJECTIVE: To develop and evaluate psychometrically a self-reported instrument assessing physical fatigability (PF) and mental fatigability (MF) in adults with spinal cord injury (SCI). DESIGN: Cross-sectional. SETTING: Peer-support groups at rehabilitation centers, online support groups. PARTICIPANTS: Adults with SCI (N=464) in the United States. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The dimensional structure was assessed by confirmatory factor analysis. The relationship between item responses and fatigability was measured with item response theory (graded response model). Reliability was measured with test information functions. Differential item functioning was evaluated with Wald chi-square tests and the weighted area between the curves. Construct validity was assessed using the known groups method. RESULTS: An 82-item pool was developed from prior qualitative research and consultations with rehabilitation experts. A non-probability sample (N=464) was used to evaluate the psychometric properties of the PF and MF scales. The item pool was reduced to 75 based on factor loadings and R2. Both scales are primarily unidimensional, despite moderate multidimensionality. There is good discrimination overall: 18 PF items and 26 MF items have high or very high discrimination power (slopes > 1.35). The measurement precision in the theta range -2.0 to 2.5 is the equivalent of 0.94 reliability for PF and 0.91 for MF. For both measures, F statistics P values were significant at P<.01, and means were higher for those with paraplegia vs quadriplegia, and for those with incomplete paraplegia. CONCLUSIONS: The Fatigability Index is the first instrument designed to assess physical and mental fatigability in adults with SCI. The index highlights causes of fatigue and areas requiring immediate intervention. Development of short-forms and further research on representative samples are necessary.