National memory path study: Formation of register-based cohorts of persons diagnosed with dementia in Finland in 2019 and 2021

AIMS: This study describes the study design and methodology for the formation of novel National Memory Path cohorts, outlined to investigate dementia incidence and health and social service use preceding dementia diagnosis in Finland before and after the onset of the COVID-19 pandemic, and to enable further national-level analyses. METHODS: A register-based study was conducted, consisting of all Finnish home-dwelling adults who received a dementia diagnosis in 2019 or 2021. Dementia was defined based on the diagnosis in the Finnish Health Care Registers, or on the prescription of an anti-dementia drug in the Finnish Prescription Centre. Health and social service use within 12 months before the diagnosis included visits to outpatient and inpatient care in primary and secondary healthcare, emergency departments and home care recorded in the Finnish Health Care Registers. RESULTS: Altogether, 23,121 and 22,419 persons were diagnosed with dementia in 2019 and 2021, respectively, corresponding to an incidence of 520 and 501 per 100,000 in mean population. The highest number of diagnoses occurred in the 75-84 age group. Within 12 months before the diagnosis, 98% had used health and social services. Outpatient care in primary healthcare was the most often used service, followed by outpatient care in secondary healthcare and emergency department use. CONCLUSIONS: National health registers enable comprehensive analysis of dementia incidence and service use. Frequent service use prior to the dementia diagnosis creates opportunities for dementia symptom detection across various parts of the health and social care system.