How does the level of functional impairment vary in individuals with non-communicable disease and comorbidity? Cross-sectional analysis of linked census and administrative data in Aotearoa New Zealand.

Objectives: This study examines national patterns of functional impairment, and how they vary by the presence of non-communicable disease (NCD), type of health condition, comorbidity, age, sex, ethnicity, deprivation and living situation.

Design: A cross-sectional examination using a national research database of linked administrative and survey data sets including census, tax and health data.

Setting: Aotearoa New Zealand PARTICIPANTS: All individuals living in NZ on 30 June 2018, identified by the Statistics NZ Integrated Data Infrastructure estimated residential population (4.79 million individuals). Nine NCDs among these individuals were identified from national health data sets using existing and adapted algorithms.

Primary And Secondary Outcome Measures: Functional impairment was assessed via hospitalisations, comorbidities (Elixhauser index), activity limitations (census) and income support.

Results: Three-tenths (29%) of the population had at least one NCD. Functional impairment was strongly patterned by NCD prevalence (3% activity limitation in people without any NCDs, 13% if one or more NCDs and 25% if two or more NCDs). Activity limitation was most common in individuals with dementia (68% activity limitation), stroke (42%) and coronary heart disease (26%). After age stratification, there was also a high level of activity limitation and income support in people with mental health conditions. Māori and Pacific peoples and people living in deprived areas or alone were more likely to have functional impairment.

Conclusions: Functional impairment was strongly patterned by NCD type. NCD prevention efforts and disability supports are needed to reduce the burden of disability experienced.