Development of a Rat Clinical Frailty Index

Amy Yorke, Alice E. Kane, Camille L. Hancock Friesen, Susan E. Howlett, Stacy O'Blenes

Research output: Contribution to journalArticlepeer-review

41 Scopus citations


Rats are a commonly used model for aging studies, and a frailty assessment tool for rats would be of considerable value. There has been a recent focus on the development of preclinical models of frailty in mice. A mouse clinical frailty index (FI) was developed based on clinical frailty assessment tools. This FI measures the accumulation of clinically evident health-related deficits in mice. This paper aimed to develop a rat clinical FI. Male Fischer 344 rats were aged from 6 to 9 months (n = 12), and from 13 to 21 months (n = 41). A FI comprised of 27 healthrelated deficits was developed from a review of the literature and consultation with a veterinarian. Deficits were scored 0 if absent, 0.5 if mild, or 1 if severe. A FI score was determined for each rat every 3-4 months, and for the older group mortality was assessed up to 21 months. Mean FI scores significantly increased at each time point for the older rats. A high FI score measured at both 17 months of age and terminally was also associated with decreased probability of survival as assessed with Kaplan-Meier curves. The rat clinical FI has significant value for use in aging and interventional studies.

Original languageEnglish (US)
Pages (from-to)897-903
Number of pages7
JournalJournals of Gerontology - Series A Biological Sciences and Medical Sciences
Issue number7
StatePublished - Jul 1 2017


  • Deficit accumulation
  • Frailty index
  • Preclinical models

ASJC Scopus subject areas

  • Aging
  • Geriatrics and Gerontology


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