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J Gerontol A Biol Sci Med Sci. 2014 Jun;69(6):621-32. doi: 10.1093/gerona/glt136. Epub 2013 Sep 19.

A clinical frailty index in aging mice: comparisons with frailty index data in humans.

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Department of Pharmacology.
Carleton Animal Care Facility.
Department of Medicine (Geriatric Medicine) and.
Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada.
Department of Pharmacology, Department of Medicine (Geriatric Medicine) and


We previously quantified frailty in aged mice with frailty index (FI) that used specialized equipment to measure health parameters. Here we developed a simplified, noninvasive method to quantify frailty through clinical assessment of C57BL/6J mice (5-28 months) and compared the relationship between FI scores and age in mice and humans. FIs calculated with the original performance-based eight-item FI increased from 0.06 ± 0.01 at 5 months to 0.36 ± 0.06 at 19 months and 0.38 ± 0.04 at 28 months (n = 14). By contrast, the increase was graded with a 31-item clinical FI (0.02 ± 0.005 at 5 months; 0.12 ± 0.008 at 19 months; 0.33 ± 0.02 at 28 months; n = 14). FI scores calculated from 70 self-report items from the first wave of the Survey of Health, Ageing and Retirement in Europe were plotted as function of age (n = 30,025 people). The exponential relationship between FI scores and age (normalized to 90% mortality) was similar in mice and humans for the clinical FI but not the eight-item FI. This noninvasive FI based on clinical measures can be used in longitudinal studies to quantify frailty in mice. Unlike the performance-based eight-item mouse FI, the clinical FI exhibits key features of the FI established for use in humans.


Deficit accumulation; Deficit index; Frailty index; Senescence.

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