New horizons in frailty: Ageing and the deficit-scaling problem

Susan E. Howlett, Kenneth Rockwood

    Research output: Contribution to journalArticlepeer-review


    All the current frailty measures count deficits. They differ chiefly in which items,and how many, they consider. These differences are related: if a measure considers only afew items, to define broad risks those items need to integrate across several systems (e.g. mobility or function). If many items are included, the cumulative effect of small deficits can be considered. Even so, it is not clear just how small deficits can be. To better understand how the scale of deficit accumulation might impact frailty measurement, weconsider how age-related, subcellular deficits might become macroscopically visible and so give rise to frailty. Cellular deficits occur when subcellular damage has neither been repaired nor cleared. With greater cellular deficit accumulation, detection becomes more likely. Deficit detection can be done by either subclinical (e.g. laboratory, imaging, electrodiagnostic) or clinical methods. Not all clinically evident deficits need cross a disease threshold. The extent to which cellular deficit accumulation compromises organ function can reflect not just what is happening in that organ system, but deficit accumulation in other organ systems too. In general, frailty arises in relation to the number of organsystems in which deficits accumulate. This understanding of how subcellular deficits might scale has implications for understanding frailty as a vulnerability state. Considering the cumulative effects of many small deficits appears to allow important aspects of the behaviour of systems close to failure to be observed. It also suggests the potential to detect frailty with less reliance on clinical observation than current methods employ. © The Author 2013. Published by Oxford University Press on behalf of the British Geriatrics Society. All rights reserved.
    Original languageEnglish
    Pages (from-to)416-423
    Number of pages7
    JournalAge and Ageing
    Issue number4
    Publication statusPublished - Jul 2013


    • Aged
    • Animal models
    • Deficit accumulation
    • Frailty index
    • Older people
    • Phenotype


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