Intellectual and physical disability, household living arrangements and COVID-19 outcomes in Scotland: protocol for a retrospective cohort study.

introductionWhile evidence consistently demonstrates elevated COVID-19 risks among people with intellectual and physical disabilities, less is known about how household living arrangements shape these inequalities. Residential setting and household size influence exposure, capacity to isolate and reliance on care yet have rarely been examined jointly with disability status at a population scale. This study aims to estimate disability-related inequalities in COVID-19 infection, hospitalisation and mortality in Scotland and to assess whether residential setting and household size modify these inequalities using linked, population-wide administrative data. METHODS AND ANALYSIS: This population-wide retrospective cohort study will use linked administrative data in Scotland. The study will focus on individuals present in the 2011 Scottish Census with records linkable to the Scottish population spine, which encompasses all individuals registered with a general practice who received a Community Health Index number. The cohort will comprise those who were alive, resident in Scotland and aged 16 years or older on 1 March 2020. Disability status will be classified from Census records as intellectual disability, physical disability (without intellectual disability) or a comparison group without reported disability. Address information recorded by the general practice will be linked to Ordnance Survey AddressBase Premium to assign Unique Property Reference Numbers. Residential settings will be classified from Basic Land and Property Unit codes as private dwellings or communal establishments and household size will be derived from resident counts at each property. Following linkage to the Public Health Scotland COVID-19 Research Database, outcomes including infection, hospitalisation and mortality will be ascertained from 1 March 2020 to 30 April 2022. Cox proportional hazards models will estimate associations between disability status, household living arrangements and COVID-19 outcomes, adjusting for relevant covariates. Effect modification will be assessed by evaluating interactions between disability status and household living arrangements on both multiplicative and additive scales. ETHICS AND DISSEMINATION: Ethical approval was granted by the College of Social Sciences Research Ethics Committee, University of Glasgow (reference: 400200099). Data linkage was approved by the Scottish Public Benefit and Privacy Panel for Health and Social Care and the Scottish Government & National Records of Scotland Data Access Panel (reference: 2021-0119). Findings will be disseminated through peer-reviewed open-access publications and conference presentations.