Development and psychometric assessment of the function-neutral health-related quality of life measure.

OBJECTIVE: The aim of this study was to determine the conceptual framework, item pool, and psychometric properties of a new function-neutral measure of health-related quality-of-life (HRQOL).

DESIGN: This is an expert panel review of existing measures of HRQOL and development of a conceptual model, core constructs, and item pool and a validation by experts in specific disabilities and in cultural competence. Items were cognitively tested, pilot tested for functional bias, field tested with a national sample of adults with various limitations, and reliability tested via repeat administration. Final item selection was based on analyses of factor structure, demographic bias, variance in likelihood of endorsement, and item-total correlation. Psychometric properties were demonstrated through differential item functioning analyses, factor analyses, correlations, and item response theory analyses.

RESULTS: The results supported a four-domain conceptual model of HRQOL (physical health, mental health, social health, and life satisfaction and beliefs) for a 42-item HRQOL measure with an ancillary 15-item environment scale. The measure has strong internal consistency (α = 0.88-0.97), known-groups validity, and test-retest reliability (r = 0.83-0.91). Tests of convergent and divergent validity confirmed the ability of the Function-Neutral Health-Related Quality of Life to measure health while being relatively free of content assessing function.

CONCLUSIONS: A conceptually grounded four-domain, function-neutral measure of HRQOL that is appropriate for use with persons with and without various functional limitations was developed.