title: Importance of home study visit capacity in dementia studies.
abstract: BACKGROUND
  The importance of home research study visit capacity in Alzheimer's disease (AD) studies is unknown.
  
  
  METHODS
  All evaluations are from the prospective Adult Changes in Thought study. Based on analyses of factors associated with volunteering for a new in-clinic initiative, we analyzed AD risk factors and the relevance of neuropathologic findings for dementia comparing all data including home visits, and in-clinic data only. We performed bootstrapping to determine whether differences were greater than expected by chance.
  
  
  RESULTS
  Of the 1781 people enrolled during 1994-1996 with ≥1 follow-up, 1369 (77%) had in-clinic data, covering 61% of follow-up time. In-clinic data resulted in excluding 76% of incident dementia and AD cases. AD risk factors and the relevance of neuropathologic findings for dementia were both different with in-clinic data.
  
  
  CONCLUSIONS
  Limiting data collection in AD studies to research clinics alone likely reduces power and also can lead to erroneous inferences.
authors.affiliation: Department of Medicine, University of Washington, Seattle, WA, USA. Electronic address: pcrane@uw.edu.
authors.forename: Paul K
authors.initials: PK
authors.lastname: Crane
authors.affiliation: Department of Medicine, University of Washington, Seattle, WA, USA.
authors.forename: Laura E
authors.initials: LE
authors.lastname: Gibbons
authors.affiliation: Department of Psychosocial & Community Health, University of Washington, Seattle, WA, USA.
authors.forename: Susan M
authors.initials: SM
authors.lastname: McCurry
authors.affiliation: Department of Medicine, University of Washington, Seattle, WA, USA.
authors.forename: Wayne
authors.initials: W
authors.lastname: McCormick
authors.affiliation: Department of Neurology, Multiple Sclerosis Center, Swedish Neuroscience Institute, Seattle, WA, USA.
authors.forename: James D
authors.initials: JD
authors.lastname: Bowen
authors.affiliation: Department of Pathology, University of Utah, Salt Lake City, UT, USA.
authors.forename: Joshua
authors.initials: J
authors.lastname: Sonnen
authors.affiliation: Department of Pathology, University of Washington, Seattle, WA, USA.
authors.forename: C Dirk
authors.initials: CD
authors.lastname: Keene
authors.affiliation: Department of Neurology, University of Washington, Seattle, WA, USA.
authors.forename: Thomas
authors.initials: T
authors.lastname: Grabowski
authors.affiliation: Department of Pathology, University of Washington, Seattle, WA, USA.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Montine
authors.affiliation: Group Health Research Institute, Seattle, WA, USA.
authors.forename: Eric B
authors.initials: EB
authors.lastname: Larson
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000175:diagnosis* / Q000473:pathology / Q000523:psychology*; D005260:Female; D005500:Follow-Up Studies; D006792:House Calls; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D009483:Neuropsychological Tests; D011446:Prospective Studies; D012107:Research Design; D012307:Risk Factors
keywords: Bias; Cohort studies; Dementia; Home research study visits; Inference; Longitudinal studies; Missing data; Neuropathology; Prospective studies; Research clinic study visits