title: Dementia in the USA: state variation in prevalence.
abstract: BACKGROUND
  The number of dementia patients will increase over the next decades. However, we lack information on the geographic distribution of these patients. We aimed to describe the variation of dementia prevalence and to then compare the observed to expected prevalence.
  
  
  METHODS
  This study is based on a 20% sample of Medicare beneficiaries in 2008. The crude dementia prevalence was calculated and age/sex standardized to the US population for states. We used the World Alzheimer Report 2009 prevalence to compare estimates.
  
  
  RESULTS
  4.8 million persons were included. The adjusted prevalence is 8.24%, varying from 5.96 to 9.55% across states. The diagnosed prevalence is lower than the expected in most states. Overall, we estimate over 100 000 undiagnosed dementia patients in Medicare.
  
  
  CONCLUSIONS
  The high state variation suggests that the number of diagnosed dementia cases does not fall evenly across all states and hence may require different levels of state-level planning.
authors.affiliation: Department of Health Services Research, Munich School of Management, LMU Munich, 80539 Munich, Germany The Dartmouth Institute for Health Policy and Clinical Practice, Geisel School of Medicine, Dartmouth College, Hanover, NH 03766, USA.
authors.forename: D
authors.initials: D
authors.lastname: Koller
authors.affiliation: The Dartmouth Institute for Health Policy and Clinical Practice, Geisel School of Medicine, Dartmouth College, Hanover, NH 03766, USA.
authors.forename: Julie P W
authors.initials: JP
authors.lastname: Bynum
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003704:Dementia / Q000453:epidemiology*; D005260:Female; D006801:Humans; D008297:Male; D015995:Prevalence; D014481:United States / Q000453:epidemiology
keywords: chronic disease; diagnosis; health services