Development and Validation of the Outcomes of WeLlbeing and Distress Scale for Adults With an Intellectual Disability (OWLS-ID), Formally Known as the PTOS-ID.
Adults with ID can reliably flag their own psychological distress using the 27-item OWLS-ID and a cut-off of 11.5.
01Research in Context
What this study did
The team built a 27-question checklist that adults with intellectual disability can answer themselves.
They tested the adults in day centers across the UK. Each person marked how often they felt sad, worried, or calm.
Statistical checks showed three clear groups of questions: mood, anxiety, and positive wellbeing.
What they found
The new OWLS-ID scale is reliable and matches well with longer clinical interviews.
A score of 11.5 or higher flags likely distress with good accuracy.
Adults with mild to moderate ID could complete the form in about five minutes with little help.
How this fits with other research
Scior et al. (2011) first showed that short self-report scales work in this population. OWLS-ID copies their three-factor math and moves from testing public knowledge to testing private feelings.
Guest et al. (2013) validated the French PAS-ADD, a caregiver checklist. OWLS-ID flips the source: it asks the adult directly, not the staff. Both tools hit similar sensitivity, but OWLS-ID gives the person a voice.
Prasher et al. (1995) proved adults with ID can report maladaptive behavior. OWLS-ID extends that idea from outward behavior to inner distress, updating the 1990s model for today’s person-centered services.
Why it matters
You now have a quick, free screen that respects client autonomy. Give OWLS-ID at intake, annual review, or when behavior spikes. A score above 11.5 triggers a fuller mental-health look and documents need for funding or therapy.
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02At a glance
03Original abstract
BACKGROUND: The Psychological Therapies Outcome Scale-Intellectual Disabilities-II (PTOS-ID-II) is a 29-item self-report measure developed to assess psychological distress and positive well-being in people with an intellectual disability. While initial validation demonstrated promising psychometric properties, further replication in a larger sample was needed, and incorporating insights gained from routine clinical use over the years since its initial implementation. METHOD: A quantitative cross-sectional design was utilised to test the psychometric properties of the PTOS-ID-II using data collected from routine clinical practice from adults with intellectual disabilities (n = 879) accessing a community health service. Subsequent analyses included dimensionality reduction (via principal component analysis and confirmatory factor analysis), assessment of internal consistency, concurrent validity and receiver operating characteristic analysis. Analyses were guided by a primer on the development of health outcome measures. RESULTS: Exploration of the proposed factor structure of the PTOS-ID-II indicated that two of the items were problematic and subsequently removed. The new 27-item measure was rebranded 'the Outcomes for Wellbeing and Distress Scale' (OWLS-ID). Analysis of the measure identified and confirmed a three-component model: (1) Positive Well-being, (2) Emotional and Behavioural Discomfort and (3) Anxiety. Internal consistency was good to acceptable. Items related to Emotional and Behavioural Discomfort and Anxiety were combined to create a measure of psychological distress. Concurrent validity between distress as measured using the OWLS-ID and Brief Symptoms Inventory was strong. A cut of 11.5 had acceptable sensitivity (0.85) and specificity (0.9). Analysis of missing data suggested that item acceptability was high. CONCLUSION: The OWLS-ID is one of the most comprehensively tested patient-reported outcome measures to date, which was developed specifically for individuals with an intellectual disability. Its implications for clinical practice and future research are discussed.
Journal of intellectual disability research : JIDR, 2026 · doi:10.1111/jir.70099