Incidence and prevalence of dementia: A 2015-2020 population-based study in the Campania Region of Italy.

OBJECTIVE To provide population-based estimates of prevalence and incidence of any dementia and Alzheimer's dementia in the Campania Region (South Italy), and to validate towards a clinical registry. METHODS Population-based study, using routinely collected healthcare data of individuals living in the Campania Region (South Italy) from 2015 to 2020. We included individuals aged ≥65 years alive at the prevalence day (1 January 2021) who had at least one administrative record for dementia and/or Alzheimer's dementia from 2015 to 2020. Age-and sex-standardised prevalence rates were calculated using direct standardisation method (European population in 2020 as reference population). To estimate incidence, we tested three possible algorithms, which differed for the duration of the time interval between study baseline (Jan 1, 2015) and index date (first record for dementia and/or Alzheimer's dementia in administrative databases). We employed a clinical database for the validation of our algorithms towards neuropsychological test results. RESULTS Among individuals aged over 65, 80,392 had dementia, of which 35,748 had Alzheimer's dementia. The age- and sex-standardized prevalence rates per 1,000 individuals for any dementia and Alzheimer's dementia were 77.64 (95%CI = 77.57; 77.68) and 34.05 (95%CI = 34.01; 34.09), respectively. There were 82.10 incident of any dementia cases per 100,000 per year (0.79 sensitivity and 0.62 specificity), and 59.89 incident cases of any dementia per 100,000 per year (0.80 sensitivity and 0.59 specificity). The capture-recapture method showed very low number of undetected cases (1.7% for any dementia and 3.0% for Alzheimer's dementia). Our algorithms showed acceptable performance with AUC ranging from 0.59 to 0.72, and double likelihood ratio of correctly identifying individuals above and below MMSE standard cut-offs (24 and 26). CONCLUSIONS Prevalence and incidence of any dementia and Alzheimer's dementia in the Campania Region (South Italy) from 2015 to 2020 are in line with previous estimates from other countries. Our algorithm, integrating administrative and clinical data, holds potential for assessing dementia's epidemiological burden, identifying risk factors, planning healthcare access, and developing prevention strategies.