title: Age-specific hospital incidence rates in dementia. A record linkage study of first-admission rates to Scottish hospitals (1968-1987).
abstract: A random sample (n = 101,104) was taken from total general hospital admissions to Scottish hospitals (1:25 fraction) during the period 1968-1977. Record linkage was used to connect general hospital and psychiatric hospital morbidity records (SMR 1 and SMR 4). Patients with a subsequent admission with dementia (principal diagnosis ICD 9,290) were identified from the general hospital sample on follow-up. Age-specific first-admission rates for dementia were calculated for the hospital population considered. First-admission rates ranged from 41.9 (per 100,000 person-years-at-risk, PYR) for male patients aged 60-64 years to 514.2 in the age band 80 years and over. The equivalent figures for female patients were 40.8 (per 100,000 PYR) and 723.1. Epidemiological research has shown an approximate doubling of prevalence rates every 5 years after the age of 60 years, and the age-banded hospital admission rates in the present study are consistent with this underlying pattern. Expected first-admission rates in dementia were calculated from admission rates in dementia and community prevalence reported in previous studies. Expected rates were contrasted with the rates observed in the present study. An estimated 6-7% of prevalent dementia cases and between 11 and 14% of 'expected dementia admissions' achieved a recorded main diagnosis of dementia, and proportions were stable across age bands in the case of both measures. The wide discrepancy between expected and observed admission rates suggests relative underreporting of dementia as a principal diagnosis in hospital statistics.
authors.affiliation: Community Mental Health Centre, Beverely, East Yorkshire, UK.
authors.forename: D H
authors.initials: DH
authors.lastname: Ryan
mesh_terms: D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D003704:Dementia / Q000453:epidemiology*; D005260:Female; D006761:Hospitals; D006801:Humans; D015994:Incidence; D008297:Male; D008498:Medical Record Linkage; D008875:Middle Aged; D010343:Patient Admission; D012606:Scotland / Q000453:epidemiology; D017678:Sex Distribution