Health state descriptions, valuations and individuals' capacity to walk: a comparative evaluation of preference-based instruments in the context of spinal cord injury.
This study explores variation in health state descriptions and valuations derived from preference-based health-related quality of life instruments in the context of spinal cord injury (SCI).



Individuals living with SCI were invited to complete a web-based, cross-sectional survey. The survey comprised questions regarding demographics, SCI classifications and characteristics, secondary health complications and conditions, quality of life and SCI-specific functioning in activities of daily living. Four preference-based health status classification systems were included; Assessment of Quality of Life 8-dimension questionnaire (AQoL-8D), EQ-5D-5L, Health Utilities Index (HUI) and SF-6D (derived from the SF-36v2). In addition to descriptive comparisons of index scores and item/dimension responses, analyses explored dimension-level correlation and absolute agreement (intraclass correlation coefficient (ICC)). Subgroup analyses examined the influence of individuals' self-reported ability to walk.



Of 609 invitations, 364 (60 %) individuals completed the survey. Across instruments, convergent validity was seen between pain and mental health dimensions, while sizeable variation pertaining to issues of mobility was observed. Mean index scores were 0.248 (HUI-3), 0.492 (EQ-5D-5L), 0.573 (AQoL-8D) and 0.605 (SF-6D). Agreement ranged from 'slight' (HUI-3 and SF-6D; ICC = 0.124) to 'moderate' (AQoL-8D and SF-6D; ICC = 0.634). Walking status had a markedly different impact on health state valuations across instruments.



Variation in the way that individuals are able to describe their health state across instruments is not unique to SCI. Further research is necessary to understand the significant differences in index scores and, in particular, the implications of framing mobility-related questions in the context of respondents' ability to walk.
Faculty of Health Sciences, Simon Fraser University, Burnaby, BC, Canada. david_whitehurst@sfu.ca.|International Collaboration on Repair Discoveries (ICORD), Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada. david_whitehurst@sfu.ca.|Centre for Clinical Epidemiology and Evaluation, Vancouver Coastal Health Research Institute, Vancouver, BC, Canada. david_whitehurst@sfu.ca.
David G T
DGT
Whitehurst
Health Outcomes and PharmacoEconomics (HOPE) Research Centre, Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Toronto, ON, Canada.|Department of Pharmacology, University of Toronto, Toronto, ON, Canada.
Nicole
N
Mittmann
Rick Hansen Institute, Vancouver, BC, Canada.
Vanessa K
VK
Noonan
International Collaboration on Repair Discoveries (ICORD), Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada.|Rick Hansen Institute, Vancouver, BC, Canada.
Marcel F
MF
Dvorak
Centre for Clinical Epidemiology and Evaluation, Vancouver Coastal Health Research Institute, Vancouver, BC, Canada.|School of Population and Public Health, University of British Columbia, Vancouver, BC, Canada.|Health Economics Research Unit, University of Aberdeen, Aberdeen, Scotland, UK.
Stirling
S
Bryan
D000203:Activities of Daily Living; D003430:Cross-Sectional Studies; D005260:Female; D006304:Health Status; D006801:Humans; D008875:Middle Aged; D011788:Quality of Life / Q000523:psychology*; D013119:Spinal Cord Injuries / Q000523:psychology*; D011795:Surveys and Questionnaires; D016138:Walking / Q000293:injuries*
Disability; Health state valuation; Health-related quality of life; Quality-adjusted life years; Spinal cord injury; Utility measurement