Prevalence and sequence of chronic conditions in older people with dementia: a multi-province, population-based cohort study.

Introduction: Comorbid chronic conditions contribute to increased health service use and poor outcomes for people with dementia, but there is little information about the prevalence of these conditions in this population.

Methods: We used linked administrative data from British Columbia (BC), Ontario (ON), Quebec (QC) and Prince Edward Island (PE) to identify a cohort of 287 453 individuals aged 65 years and older with prevalent dementia in April 2015, and followed this population until March 2020. We determined the prevalence of comorbid chronic conditions and ascertainment dates using Canadian Chronic Disease Surveillance System definitions, and used descriptive statistics to compare patterns across provinces.

Results: Sociodemographic characteristics were similar across provinces (mean age: 83.0 [PE]-84.3 [BC] years; female sex: 61.8% [BC]-66.2% [QC]; and long-term care facility residence: 39.5% [QC]-41.6% [BC]). People with dementia commonly experienced five or more comorbid conditions (38.8% [PE]-53.5% [ON]); the most prevalent were hypertension (76.4% [PE]-81.4% [ON]), mental illness and alcohol- or druginduced disorders (44.4% [QC]-91.2% [BC]) and osteoarthritis (43.8% [PE]-60.4% [ON]). Hypertension, diabetes and stroke were frequently apparent before dementia ascertainment, whereas heart failure and traumatic brain injury were apparent almost as frequently after dementia ascertainment as before.

Conclusion: Patterns of comorbid chronic conditions were similar across provinces, with most present prior to dementia ascertainment. Health service planning strategies should be developed and shared across provinces to address the complex health care needs of people with dementia.