title: The Danish 1905 cohort: a genetic-epidemiological nationwide survey.
abstract: OBJECTIVE
  The authors studied nonagenarians, a rapidly growing age group whose cognitive and physical abilities have yet to be investigated systematically.
  
  
  METHODS
  All Danes born in 1905 were invited to participate in a home-based 2-hour multidimensional interview, including cognitive and physical performance tests and collection of DNA, carried out by lay interviewers.  Population-based registers were used to evaluate representativeness.
  
  
  RESULTS
  There were 2,262 participants. A total of 1,632 (72%) gave a DNA sample.  Participants and nonparticipants were highly comparable with regard to marital status, institutionalization, and hospitalization patterns, but men and rural area residents were more likely to participate.  Six months after the survey began, 7.2% of the participants and 11.8% of the nonparticipants had died.
  
  
  CONCLUSIONS
  Despite the known difficulties of conducting surveys among the extremely old, it was possible to conduct a nationwide survey, including collection of DNA, among more than 2,000 fairly nonselected nonagenarians using lay interviewers.
authors.affiliation: Odense University.
authors.forename: H
authors.initials: H
authors.lastname: Nybo
authors.forename: D
authors.initials: D
authors.lastname: Gaist
authors.forename: B
authors.initials: B
authors.lastname: Jeune
authors.forename: L
authors.initials: L
authors.lastname: Bathum
authors.forename: M
authors.initials: M
authors.lastname: McGue
authors.forename: J W
authors.initials: JW
authors.lastname: Vaupel
authors.forename: K
authors.initials: K
authors.lastname: Christensen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D015331:Cohort Studies; D003718:Denmark; D005260:Female; D015577:Geriatric Assessment; D006306:Health Surveys; D006801:Humans; D007407:Interviews as Topic / Q000379:methods*; D008297:Male; D017422:Sequence Analysis, DNA