Developing an item bank to measure economic quality of life for individuals with disabilities

Objective To develop and evaluate the psychometric properties of an item set measuring economic quality of life (QOL) for use by individuals with disabilities. Design Survey. Setting Community settings. Participants Individuals with disabilities completed individual interviews (n=64), participated in focus groups (n=172), and completed cognitive interviews (n=15). Inclusion criteria included the following: traumatic brain injury, spinal cord injury, or stroke; age ≥18 years; and ability to read and speak English. We calibrated the items with 305 former rehabilitation inpatients. Interventions None. Main Outcome Measure Economic QOL. Results Confirmatory factor analysis showed acceptable fit indices (comparative fit index=.939, root mean square error of approximation=.089) for the 37 items. However, 3 items demonstrated local item dependence. Dropping 9 items improved fit and obviated local dependence. Rasch analysis of the remaining 28 items yielded a person reliability of.92, suggesting that these items discriminate about 4 economic QOL levels. Conclusions We developed a 28-item bank that measures economic aspects of QOL. Preliminary confirmatory factor analysis and Rasch analysis results support the psychometric properties of this new measure. It fills a gap in health-related QOL measurement by describing the economic barriers and facilitators of community participation. Future development will make the item bank available as a computer adaptive test.