title: Comparison of centre and home-based health assessments: early experience from the Irish Longitudinal Study on Ageing (TILDA).
abstract: BACKGROUND
  some cohort studies of ageing and health supplement questionnaire-based surveys with in-home measurements of biological parameters and others have required respondents to attend assessment centres. Centre-based assessments facilitate detailed measurements and novel technologies, but may differentially influence participation. The aim of this paper is to compare the characteristics of participants who attended a centre with those who chose a home assessment and those who did not have a health assessment.
  
  
  METHODS
  trained field workers administered a computer-assisted personal interview (CAPI) to a random sample of community-dwelling people aged 50 and over in the participants' homes. All questionnaire respondents were invited to attend an assessment centre for a comprehensive physical assessment. Participants who refused or were unable to attend a centre were offered a home assessment.
  
  
  RESULTS
  of the 291 participants who completed the CAPI, 176 had a health assessment: 138 in an assessment centre and 38 in their own home. The centre, home and no visit respondents differed in demographic characteristics, behavioural factors, physical functioning and health. Lower socio-economic status, physical inactivity and current smoking were the most robust predictors of non-participation in the health assessment. Home respondents had the highest levels of physical disability and were much weaker (grip strength) and slower (walking speed) than centre respondents.
  
  
  CONCLUSIONS
  home and centre physical assessments are required to avoid systematically over-representing healthier and wealthier respondents.
authors.affiliation: Epidemiology and Public Health, University College Cork, Cork, Ireland. patricia.kearney@tcd.ie
authors.forename: Patricia M
authors.initials: PM
authors.lastname: Kearney
authors.forename: Hilary
authors.initials: H
authors.lastname: Cronin
authors.forename: Claire
authors.initials: C
authors.lastname: O'Regan
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Kamiya
authors.forename: Brendan J
authors.initials: BJ
authors.lastname: Whelan
authors.forename: Rose Anne
authors.initials: RA
authors.lastname: Kenny
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D003151:Community Health Centers; D005260:Female; D015577:Geriatric Assessment; D006699:Home Care Services; D006801:Humans; D007494:Ireland; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D051346:Mobility Limitation; D010358:Patient Participation; D010865:Pilot Projects; D012923:Social Class