Primary care service utilisation pattern in dementia: a 10-year longitudinal population-based study

BACKGROUND: Primary care services play a key role in dementia care, yet activity may vary between subtypes. OBJECTIVE: To investigate longitudinal determinants of primary care contact across Alzheimer's disease (ad), vascular dementia (VD), dementia with Lewy bodies (DLB), and Parkinson's disease dementia (PDD) 5 years pre-and-post-diagnosis, encompassing clinical, cognitive, functional, and sociodemographic factors. DESIGN: Retrospective cohort study. METHODS: Data on 4384 individuals with first dementia diagnoses (2008-2023) were obtained from a South London catchment linking dementia services with primary care records. Linear mixed-effects models were run on 3-month interval counts (up to 40 intervals per individual, 20 pre-and-post-diagnosis). Separate pre-and-post-diagnosis models assessed longitudinal trends, adjusted for age, sex, and antidepressant use, with subgroup analyses by dementia subtype and cognitive status. RESULT: Service utilisation increased over time, with VD showing a steeper pre-diagnosis rise and PDD moderate post-diagnosis increases compared to ad. Across both periods, worse cognitive impairment and antipsychotic receipt were associated with lower contacts, while older age and Black/British Black ethnicity were associated with higher contact. Pre-diagnosis, agitation, depressed mood, relationship and living conditions problems were linked to lower contact, whereas hallucinations were associated with higher use. Post-diagnosis, hypnotic/anxiolytic use predicted lower contact, while acetylcholinesterase inhibitor receipt, comorbidities, daily living difficulties, and mixed ethnicity were associated with increased utilisation. CONCLUSION: Person-centred care pathways should anticipate subtype-specific and individual patterns, providing targeted support for those with reduced pre-diagnosis contact who may have unmet needs, while considering early intervention for groups anticipated to require increased service use after diagnosis.