Frailty: Theoretical Frameworks
There is a lot of debate in the literature about what constitutes “frailty”. Geriatricians and health care professionals that work with older adults tend to be able to agree what a person who is frail looks like. But in order for researchers to conduct the research that is necessary for us to evaluate appropriate interventions and determine the best clinical care for these persons, it is important to have a robust theoretical framework in which to conduct these studies.
The current consensus on the definition of frailty is that frailty is “Frailty is a clinical state in which there is an increase in an individual’s vulnerability for developing increased dependency and/or mortality when exposed to a stressor.”1
Currently there are two frameworks that are often referred to in the development of outcome measures and inclusion criteria for studies looking at this population: Fried’s Physical Phenotype and Rockwood’s Accumulation of Deficits. There are many overlapping constructs between the two frameworks but the way they quantify frailty is slightly different.
The Physical Phenotype of Frailty
Fried’s framework outlines five criteria related to labelling a person as frail2.
• Physical Inactivity
• Weakness/ low muscle strength
• Slow gait speed
• Exhaustion/ fatigue
• Weight loss
Three or more of these criteria would identify a person as frail. One to two would be considered “pre-frail” and none of these criteria were labelled as robust. The original paper by Fried in 2001 showed that using this outline, frailty predicted mortality risk, falls, and disability. There is debate in the literature about the best way to quantify these parameters. Different studies have used slightly different permutations of each and that in and of itself creates inconsistency. Based on changes in cut off scores, a systematic review comparing the definitions have shown that the estimated prevalence of frailty in the same data set can be drastically different, as much as 10%3.
This framework focusses solely on the physical attributes of frailty. Persons argue that framework is incomplete because it does not address cognitive aspects or chronic conditions which have also been associated with frailty. The use of these physical criteria to label persons as frail has been shown to be predictive of lower body system markers indicative of chronic disease or dysfunction4.
This creates the argument and the question:
What is the main attribute that would label a person as frail?
Accumulation of Deficits Framework
The Accumulation of Deficits approach considers the number of conditions present in the individual and gives the person a score of 0 to 1 known as the Frailty Index. The score is calculated through the (total number of impairments in the individual)/ (the total number of impairments examined). Conditions range from diabetes, visual issues, to mental health concerns and difficulties with mobility around the house. This model dichotomizes each variable, you either have the condition or you do not. The higher your score towards one, the more frail you are considered with the presence of 8-9 issues being the cut off number for frailty (0.3)5.
Epidemiological studies has shown that this Frailty Index has a high predictive ability for mortality in both men and women 5.
Both theoretical frameworks can be referenced and are valid in the literature though work is being done to create a unified picture of frailty to ensure proper execution of research related to frailty. Fried’s criteria focusses solely on the physical aspects of frailty whereas Rockwood considers other deficits and chronic conditions.
1. Morley JE, Vellas B, Abellan van Kan G, Anker SD, Bauer JM, Bernabel R et al. Frailty consensus: a call to action. J Am Med Dir Assoc. 2013. 14(6): 392-7.
2. Fried LP, Tangen CM, Walston J, Newman AB, Hirsch C, Gottdiener J, Seeman T et al. Frailty in older adults: evidence for a phenotype. J Gerontol. 2001. 56A(3): 146-56.
3. Theou O, Cann L, Blodgett J, Wallace LMK, Brothers TD, Rockwood K. Modifications to the frailty phenotype criteria: systematic review of the current literature and investigation of 262 frailty phenotypes in the survey of health, ageing, and retirement in Europe. Ageing Res Rev. 2015. 21: 78-94.
4. Fried LP, Xue QL, Cappola AR, Ferrucci L, Chanves P, Varadhan R, Guralnik JM, Leng SX, Semba RD, et al. Nonlinear multisystem physiological dysregulation associated with frailty in older women: implications for etiology and treatment. J Gerontol. 2009. 64(10): 1049-57.
5. SongX, Mitnitski A, Rockwood MD. Prevalence and 10-year outcomes of frailty in older adults in relation to deficit accumulation. J Am Geriatr Soc. 2010. 58: 681-7.