Transfer bias and the association of cognitive impairment with falls

David M. Buchner, Eric B. Larson

Research output: Contribution to journalArticlepeer-review


The authors hypothesized that cognitive impairment is associated with falls in older adults, but that transfer bias may obscure this association in cross-sectional community studies. The bias would arise if demented patients who fall are relatively unavailable to community surveys due to death or institutionalization. To test this hypothesis, a “dose-response” relationship between falls and cognitive impairment was tested for using data from a longitudinal cohort study of 157 patients with Alzheimer-type dementia. In a cross-sectional analysis of baseline data, when 96% of the cohort were community residents, the association between falls and cognitive impairment was insignificant (odds ratio for a 10-point change in Mini-mental State score =1.2, 95% confidence interval 0.76–1.9). Yet cognitive impairment at baseline predicted falls during three-year follow-up (OR=1.8, 95% CI 1.1–3.0). Both severity of dementia and falls were risk factors for death or institutionalization. Patients at highest risk for leaving the community during follow-up were those who became non-ambulatory. The authors conclude, based on longitudinal data, that there is a dose-response effect between cognitive impairment and falls. Transfer bias probably obscured the association at baseline. These data emphasize the importance of prospective studies of falls.

Original languageEnglish (US)
Pages (from-to)254-259
Number of pages6
JournalJournal of General Internal Medicine
Issue number3
StatePublished - May 1988


  • cognitive impairment
  • dementia
  • elderly
  • falls

ASJC Scopus subject areas

  • Internal Medicine


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