Author
TOWNSEND-WHITE C.; PHAM A.N.T.; VASSOS M.V.;
Title
A systematic review of quality of life measures for people with intellectual disabilities and challenging behaviours.
Journal citation/publication details
Journal of Intellectual Disability Research, 56(3), March 2012, pp.270-284.
Summary
Six of the twenty-four quality of life instruments identified, were considered to be psychometrically sound and were assessed against 24 criteria developed from the consumer outcome measurement literature. None of the instruments were specifically developed for use with people with intellectual disability. One scale, the Multifaceted Lifestyle Satisfaction Scale, performed well in most respects but suffered from a lack of replication; a criticism applied to all of the instruments studied in detail. The need for further development and validation of quality of life measures for use with people who display challenging behaviour, or have intellectual disabilities, is emphasised.
Context
Quality of life (QOL) in individual service users is a key outcome measure in the evaluation of services and interventions aimed at people with intellectual disabilities. The aim of this study was to ‘systematically review QOL measures that could be used routinely by researchers and service providers in measuring subjective and objective QOL for people who have an ID (intellectual disability). Instruments that specifically measured the QOL of people with ID and challenging behaviours were also sought’.
Methods
What sources were searched?
The electronic databases Medline, PsycINFO, ERIC, and CINAHL were searched from 1980, when QOL was first studied in relation to people with ID, to 2008. Additional studies were sought by contacting experts in the field, screening the reference lists of systematic reviews and relevant studies, and searching the grey literature - including a range of ‘scholarly databases, resource catalogues and websites of government agencies and non-government organisations’
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What search terms/strategies were used?
Searches were conducted using a combination of controlled thesaurus descriptors, keywords, and synonyms to describe intellectual disability, quality of life, and outcome measures. Searches were adapted according to the requirements of the individual databases; the terms used in each of the four electronic databases are listed in Appendix 1.
What criteria were used to decide which studies to include?
Studies published in peer-reviewed journals and focusing on domain measurement of QOL in people with learning, developmental, or intellectual disability were eligible for inclusion. The eight core domains considered were emotional wellbeing, interpersonal relationships, material wellbeing, personal development, physical wellbeing, self-determination, social inclusion, and rights. Articles on purely health-related QOL measures, and instruments developed for a specific age-range or a restrictive sample, were excluded. Theoretical papers, diagnostic instruments, and observational studies were also rejected.
Who decided on their relevance and quality?
Articles were initially screened on the basis of titles only, and then with reference to the abstracts. Potentially relevant articles were then read in full ‘by at least one author’. It is not clear who participated in the screening process. A flowchart of the systematic review protocol is presented as Figure 1. Study quality was assessed on the basis of the QOL instrument used. Included instruments had to: assess domains that align with the eight core domains of QOL; take no more than two hours to administer; include psychometric data, and; be available in English.
How many studies were included and where were they from?
Database searching resulted in the retrieval of a total of 3,081 articles. The number was reduced to 404 after title and abstract screening, and then to 273 articles, after examination of the full text. Twenty-four measures were considered for evaluation, six of which were selected for full review against 24 assessment criteria: the Multifaceted Life Satisfaction Scale (MLSS), the Comprehensive Quality of Life Scale (Com-QOL-ID), the Quality of Life Questionnaire (QOL-Q), the Personal Wellbeing Index (PWI-ID), the Quality of Life Interview Schedule (QUOLIS), and the Evaluation of Quality of Life Instrument (EQLI). There is no indication of where the instruments were developed.
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How were the study findings combined?
This is a narrative review. The results of the assessment of the six instruments included in the final review are reported in terms of the 24 criteria which relate to reliability, validity, acquiescence, norms and pilot testing, and administration. The criteria are presented for each of the six instruments in Table 2, and summarised in Table 3 in terms of reliability and validity.
Findings of the review
No instruments for the measurement of QOL specifically in people with ID or challenging behaviour were found. The most psychometrically sound of the six instruments assessed in detail was the Multifaceted Lifestyle Satisfaction Scale (MLSS); the scale showed evidence of adequate internal consistency, test-retest reliability, inter-rater reliability, and construct validity. However, the study had only been validated by the authors and it did not measure all of the eight accepted domains of QOL. The only measure that did was the Quality of Life Questionnaire (QOL-Q) but the usefulness of the measure was limited by the lack of reliability of one of the subscales.
Only one of the scales, the Comprehensive Quality of Life Scale (Com-QOL –ID), measured domains on objective and subjective QOL on separate axes, but its use could not be recommended because of problems with validity. The Personal Wellbeing Index (PWI-ID) was developed in its place but remains to be validated empirically.
Two measures relied mostly on proxy responses: the Quality of Life Interview Schedule (QUOLIS), and the Evaluation of Quality of Life Instrument (EQLI). The latter could be a useful tool to gauge staff perceptions of individuals with ID who may be at risk of dissatisfaction. Only three of the six measures assessed acquiescent responding, a socially biased response common in people with ID; they were MLSS, Com-QOL-ID, and PWI-ID.
Authors' conclusions
‘There are several QOL measures for people with ID. Of these a limited number are psychometrically sound and potentially suitable for routine measurement of QOL among people with ID according to criteria we developed from consumer outcome measurement literature. However, no universally accepted ‘gold standard’ instrument exists for assessing the QOL of adults with ID who exhibit challenging behaviour.’
Implications for policy or practice
None are discussed.