Effect of long-term care and pandemic wave on relative risk of COVID-19-related infection, hospitalization and mortality in people living with dementia: A population-based cohort study.

BackgroundPeople living with dementia (PLWD) are vulnerable to serious COVID-19 illness and death but the contribution of various factors including long-term care (LTC), pandemic wave, hospitalization, comorbidities, and underlying neurological health remains unclear.ObjectiveTo investigate the relative risk of SARS-CoV-2 infection, hospitalization, and mortality (COVID-19 and non-COVID-19) in PLWD compared to those without dementia, by living circumstance and pandemic wave, while controlling for additional risk factors.MethodsA cohort of people 65 and up with dementia, including Alzheimer's disease, was propensity score matched to a control cohort using linked population-level health records. Relative risk of outcomes was estimated using adjusted Cox proportional hazards modelling. The modifying effects of LTC residence and pandemic wave on all outcomes, and of COVID-19-related hospitalization on COVID-19 mortality were investigated.ResultsCompared to controls without dementia, PLWD had higher risk of infection and COVID-19 mortality whether they lived in LTC or not. For PLWD in LTC, relative risk was often reduced or not significantly different when stratified by wave but remained higher for PLWD not in LTC (32-93%). In LTC, likelihood of hospitalization was 53-64% lower for PLWD compared to those without dementia. PLWD not hospitalized for COVID-19 had higher COVID-19 mortality than non-hospitalized, non-dementia controls both in and not in LTC (32% and 477%, respectively).ConclusionsPLWD repeatedly had higher risk of COVID-19 infection and mortality, but risk varied with changing pandemic circumstances and living environment. Higher mortality may have been associated with reduced hospital transfers, complex care needs and neurological health.