title: Estimating the prevalence of dementia using multiple linked administrative health records and capture-recapture methodology.
abstract: BACKGROUND
  Obtaining population-level estimates of the incidence and prevalence of dementia is challenging due to under-diagnosis and under-reporting. We investigated the feasibility of using multiple linked datasets and capture-recapture techniques to estimate rates of dementia among women in Australia.
  
  
  METHODS
  This work is based on the Australian Longitudinal Study on Women's Health. A random sample of 12,432 women born in 1921-1926 was recruited in 1996. Over 16 years of follow-up records of dementia were obtained from five sources: three-yearly self-reported surveys; clinical assessments for aged care assistance; death certificates; pharmaceutical prescriptions filled; and, in three Australian States only, hospital in-patient records.
  
  
  RESULTS
  A total of 2534 women had a record of dementia in at least one of the data sources. The aged care assessments included dementia records for 79.3% of these women, while pharmaceutical data included 34.6%, death certificates 31.0% and survey data 18.5%. In the States where hospital data were available this source included dementia records for 55.8% of the women. Using capture-recapture methods we estimated an additional 728 women with dementia had not been identified, increasing the 16 year prevalence for the cohort from 20.4 to 26.0% (95% confidence interval [CI] 25.2, 26.8%).
  
  
  CONCLUSIONS
  This study demonstrates that using routinely collected health data with record linkage and capture-recapture can produce plausible estimates for dementia prevalence and incidence at a population level.
authors.affiliation: School of Public Health, University of Queensland, Brisbane, QLD 4006 Australia.
authors.forename: Michael
authors.identifier: 0000-0002-1050-4574
authors.initials: M
authors.lastname: Waller
authors.affiliation: School of Public Health, University of Queensland, Brisbane, QLD 4006 Australia.
authors.forename: Gita D
authors.initials: GD
authors.lastname: Mishra
authors.affiliation: School of Public Health, University of Queensland, Brisbane, QLD 4006 Australia.
authors.forename: Annette J
authors.initials: AJ
authors.lastname: Dobson
keywords: Capture–recapture; Dementia; Incidence; Linked data; Prevalence