Health Technology Assessment (Jan 2012)
Development of a social inclusion index to capture subjective and objective life domains (Phase II): psychometric development study
Abstract
Objectives: To produce a robust measure of social inclusion [Social and Community Opportunities Profile (SCOPE)] that is multidimensional and captures multiple life domains; incorporates objective and subjective indicators of inclusion; has sound psychometric properties including responsiveness; facilitates benchmark comparisons with normative general population and mental health samples [including common mental disorder (CMD) and severe mental illness groups]; can be used with people with mental health problems receiving support from mental health services or not; and can be used across a range of community service settings. Design: Phase I: conceptual framework developed from a review of the literature and concept mapping. Phase II: questionnaire developed including UK national population surveys and other normative data. Pre-testing using cognitive appraisal and evaluation then pilot testing in a small convenience sample. Preliminary testing (following modification) in community (n = 252) and mental health service users (MHSUs) samples (n = 43). Data reduction including factor analysis and Mokken scaling for polytomous item response analysis then psychometric evaluation, including internal consistency and discriminant and construct validity. Test–retest reliability assessed in a convenience sample of students (n = 119). Final testing in clinical services including psychometric evaluation and responsiveness testing. Setting: The community sample was set in participants’ households across the UK. The MHSU sample was set in a south Wales resource centre. The student sample was set in a university. Participants: The community sample was randomly selected from the postal address file in five areas in England and Wales. Forty people in this sample were subgrouped as having a CMD based on their responses to the Mental Health Index five items. Two MHSU samples were obtained from existing services. Results: Psychometric testing on the field data from the SCOPE long version demonstrated good internal consistency of all scales (alpha ≥ 0.7), good construct validity, with SCOPE scales correlating highly with each other sharing between 40% and 61% of variance and a close but lesser association with community participation and social capital. Chi-squared tests on objective items and analysis of variance between groups on SCOPE scales demonstrated good discriminant validity between different mental health groups (and better than the Mokken scaling results). Acceptability was good, with 77% of the service user sample finding the SCOPE domains relevant. The number of items in SCOPE decreased from 121 to 48 following data reduction. Scales in the short version of SCOPE retained reasonable internal consistency (alpha between 0.60 and 0.75). Test–retest reliability demonstrated reliability over time, with strong associations between all items over a 2-week period. Repeating the discriminant validity tests on the short version demonstrates good discriminant validity between the mental health groups. Acceptability improved, with 90% of the sample describing questions as relevant to them. Conclusions: The main aim of producing an instrument with good psychometric properties for use in research and clinical settings, namely the SCOPE short version, was achieved. Ongoing data collection will enable responsiveness testing in the future. Further research is needed including larger samples of minority and disadvantaged groups, including those with physical illnesses and disabilities, and specific mental health diagnostic groups. Funding: The National Institute for Health Research Health Technology Assessment programme.
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