Liam M Hannan1,2,3,4, David G T Whitehurst5,6,7, Stirling Bryan7,8,9, Jeremy D Road10,11, Christine F McDonald12,13,14,15, David J Berlowitz12,13,14,15, Mark E Howard12,13,14,15. 1. Institute for Breathing and Sleep, Austin Health, PO Box 5555, Heidelberg, VIC, 3084, Australia. liam.hannan@austin.org.au. 2. Department of Respiratory and Sleep Medicine, Austin Health, Victoria, Australia. liam.hannan@austin.org.au. 3. Medicine, Dentistry, and Health Science, University of Melbourne, Victoria, Australia. liam.hannan@austin.org.au. 4. Victorian Respiratory Support Service, Austin Health, Victoria, Australia. liam.hannan@austin.org.au. 5. Faculty of Health Sciences, Simon Fraser University, Burnaby, BC, Canada. 6. International Collaboration on Repair Discoveries (ICORD), Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada. 7. Centre for Clinical Epidemiology and Evaluation, Vancouver Coastal Health Research Institute, Vancouver, BC, Canada. 8. School of Population and Public Health, University of British Columbia, Vancouver, BC, Canada. 9. Health Economics Research Unit, University of Aberdeen, Aberdeen, Scotland, UK. 10. Department of Medicine, University of British Columbia, Vancouver, BC, Canada. 11. Provincial Respiratory Outreach Program, Vancouver, BC, Canada. 12. Institute for Breathing and Sleep, Austin Health, PO Box 5555, Heidelberg, VIC, 3084, Australia. 13. Department of Respiratory and Sleep Medicine, Austin Health, Victoria, Australia. 14. Medicine, Dentistry, and Health Science, University of Melbourne, Victoria, Australia. 15. Victorian Respiratory Support Service, Austin Health, Victoria, Australia.
Abstract
PURPOSE: To explore the influence of descriptive differences in items evaluating mobility on index scores generated from two generic preference-based health-related quality of life (HRQoL) instruments. METHODS: The study examined cross-sectional data from a postal survey of individuals receiving assisted ventilation in two state/province-wide home mechanical ventilation services, one in British Columbia, Canada and the other in Victoria, Australia. The Assessment of Quality of Life 8-dimension (AQoL-8D) and the EQ-5D-5L were included in the data collection. Graphical illustrations, descriptive statistics, and measures of agreement [intraclass correlation coefficients (ICCs) and Bland-Altman plots] were examined using index scores derived from both instruments. Analyses were performed on the full sample as well as subgroups defined according to respondents' self-reported ability to walk. RESULTS: Of 868 individuals receiving assisted ventilation, 481 (55.4%) completed the questionnaire. Mean index scores were 0.581 (AQoL-8D) and 0.566 (EQ-5D-5L) with 'moderate' agreement demonstrated between the two instruments (ICC = 0.642). One hundred fifty-nine (33.1%) reported level 5 ('I am unable to walk about') on the EQ-5D-5L Mobility item. The walking status of respondents had a marked influence on the comparability of index scores, with a larger mean difference (0.206) and 'slight' agreement (ICC = 0.386) observed when the non-ambulant subgroup was evaluated separately. CONCLUSIONS: This study provides further evidence that between-measure discrepancies between preference-based HRQoL instruments are related in part to the framing of mobility-related items. Longitudinal studies are necessary to determine the responsiveness of preference-based HRQoL instruments in cohorts that include non-ambulant individuals.
PURPOSE: To explore the influence of descriptive differences in items evaluating mobility on index scores generated from two generic preference-based health-related quality of life (HRQoL) instruments. METHODS: The study examined cross-sectional data from a postal survey of individuals receiving assisted ventilation in two state/province-wide home mechanical ventilation services, one in British Columbia, Canada and the other in Victoria, Australia. The Assessment of Quality of Life 8-dimension (AQoL-8D) and the EQ-5D-5L were included in the data collection. Graphical illustrations, descriptive statistics, and measures of agreement [intraclass correlation coefficients (ICCs) and Bland-Altman plots] were examined using index scores derived from both instruments. Analyses were performed on the full sample as well as subgroups defined according to respondents' self-reported ability to walk. RESULTS: Of 868 individuals receiving assisted ventilation, 481 (55.4%) completed the questionnaire. Mean index scores were 0.581 (AQoL-8D) and 0.566 (EQ-5D-5L) with 'moderate' agreement demonstrated between the two instruments (ICC = 0.642). One hundred fifty-nine (33.1%) reported level 5 ('I am unable to walk about') on the EQ-5D-5L Mobility item. The walking status of respondents had a marked influence on the comparability of index scores, with a larger mean difference (0.206) and 'slight' agreement (ICC = 0.386) observed when the non-ambulant subgroup was evaluated separately. CONCLUSIONS: This study provides further evidence that between-measure discrepancies between preference-based HRQoL instruments are related in part to the framing of mobility-related items. Longitudinal studies are necessary to determine the responsiveness of preference-based HRQoL instruments in cohorts that include non-ambulant individuals.