The adult social care outcomes toolkit easy read for older people (ASCOT-ER OP): an exploratory factor analysis and Rasch validation study

ASCOT easy read for older people (ASCOT-ER OP) is an adaptation of the Adult Social Care Outcomes Toolkit (ASCOT-SCT4) that was co-produced with older adults and their families to improve accessibility and feasibility of completion. This study aimed to examine the structural validity of ASCOT-ER OP using exploratory factor analysis (EFA) and Rasch analysis. Data were collected by British Red Cross (BRC) as part of short-term support for adults living at home, post-crisis or hospital discharge (‘Support at Home’). ASCOT-ER OP was collected at initial assessment (baseline) and at the end of support (follow-up), typically no longer than 12 weeks later. Only follow-up data were analysed in this study. EFA was conducted to assess structural validity against the single factor structure of ASCOT-SCT4. Overall fit to the Rasch model was examined alongside assessment of unidimensionality, local independence, item fit, response threshold ordering and differential item functioning (DIF) by age group (18–64 and 65 + years). ASCOT-ER OP had a single factor structure in EFA. There was good fit to the Rasch model without significant breach of assumptions. Item fit was satisfactory. There was no evidence of disordered thresholds, but suboptimal distinguishability between response categories at some thresholds. These aligned to instances of < 10 ratings per category and/or were consistent with the properties of the ASCOT-SCT4. There was evidence of DIF by age group for two items: Personal Safety and Home comfort and cleanliness. EFA and Rasch support the structural validity of ASCOT-ER OP as a unidimensional measure.