Research Perspective|Volume 17, Issue 9|pp 2241—2251

Analysis of the current state of frailty indexes and their implementation for aging intervention studies

Oliver G. Frost^1,², Anna Barkovskaya², Michael J. Rae², Marcela Atzori², Abdelhadi Rebbaa², Amit Sharma²

¹Centre for Biological Engineering, School of Mechanical, Electrical and Manufacturing Engineering, Loughborough University, Loughborough LE11 3TU, UK
²Lifespan Research Institute, Mountain View, CA 94041, USA

* Equal contribution

Received: March 14, 2025Accepted: August 13, 2025Published: August 26, 2025

https://doi.org/10.18632/aging.206307

Copyright: © 2025 Frost et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Abstract

Animal lifespan studies are foundational to developing interventions against the biological aging process. In recent years, there has been rising interest in characterizing the effects of longevity therapeutics on health span. Frailty indexes, originally developed to assess clinical frailty in aging humans, have shown promise as measurements of biological age and have been adopted for use in rodent aging biology. This Perspective looks at the current state of rodent frailty indexes and how they are implemented. The differences in frailty parameters used to calculate these indexes have led to inconsistencies between studies defining frailty. In this Perspective, we have highlighted those differences and made recommendations for implementing protocols for frailty index measurement.