Measuring what matters to older persons for active living: part II cross-sectional validity evidence for OPAL measure across four countries
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INTRODUCTION: Through interviews with 148 older persons from four countries and in four languages, the content for a 17-item measure of active living was developed. The purpose of this paper is to present further evidence of the extent to which this new measure, Older Persons Active Living (OPAL), is "fit-for-purpose" for measuring the extent of active living at one point in time. METHODS: A cross-sectional study was carried out on a population aged 65 + and living independently, drawn from a participant panel, HostedinCanada, sampling people from Canada, United States, United Kingdom, and Netherlands. The survey instrument comprised the OPAL questionnaire rated on importance and frequency, sociodemographics, and information on physical and mental function. The argument-based approach to validity framed the analyses. Logistic regression, structural equation modeling, ordinary least-squares regression, and correlation were used to generate estimates for parameters underpinning validity evidence. RESULTS: A total of 1612 people completed the survey, 100 to 400 people across the 6 country-language strata. The proportion of people rating the items as extremely or quite important ranged from 60 to 90%, with no important differences between men and women and few differences between strata. A single-factor structure was supported. The ordinality of the response options justified an additive total score yielding a near normal distribution (mean: 33.1; SD: 11.5; range 0-51). Correlations with other measures of converging constructs were of moderate strength (~ 0.50), and differences across groups known to affect functioning and health were observed, suggesting a Miminal Important Difference (MID) of 6 out of 51. CONCLUSION: The results of this study provide evidence that the 17-item OPAL measure is fit for the purpose of estimating the extent to which older persons are living actively at one point in time.
