Background and Objectives
The relationship between frailty and disability in activities of daily living (ADLs) can be seen in different ways, with disability being—to varying degrees—a characteristic, negative outcome, or predictor of frailty. This conflation of definitions is partly a result of the different frailty tools used in research. Aiming to provide a comprehensive overview, this systematic literature search analyzed (i) if, (ii) to what extent, and (iii) how ADLs are evaluated by frailty instruments.
Research Design and Methods
A search was performed in PubMed, Web of Knowledge, and PsycINFO to identify all frailty instruments, followed by categorization of the ADL items into basic (b-), instrumental (i-), and advanced (a-) ADLs.
Results
In total, 192 articles described 217 frailty instruments, from which 52.1% contained ADL items: 45.2% b-ADLs, 35.0% i-ADLs, and 10.1% a-ADLs. The most commonly included ADL items were bathing (b-ADLs); using transportation (i-ADLs); and semiprofessional work engagement in organized social life or leisure activities (a-ADLs). These instruments all had a multidomain origin (χ 2 = 122.4, p < .001).
Discussion and Implications
Because 52.1% of all instruments included ADL items, the concepts of frailty and disability appear to be highly entangled. This might lead to circular reasoning, serious concerns regarding contamination, and invalid research results.
Frailty is highly prevalent in old age and confers an important mortality risk. Although the causes of frailty are multiple, immuno-senescence (IS) - predominantly driven by cytomegalovirus (CMV) - has been implicated in its pathophysiology. Thus far, research examining the association between IS and frailty states is sparse and equivocal. On the other hand, evidence is mounting in support of the view that frailty can be reversed, especially for those in the pre-frail stage. Therefore, we aimed to clarify the impact of CMV on IS and its relevance to pre-frailty. 173 persons aged 80 to 99 years were enrolled. Pre-frailty was defined according to Fried's criteria. Anti-CMV IgG and serum IL-6 were measured using Architect iSystem and Luminex, respectively. T-cell phenotypes were determined using flow cytometry. The prevalence of pre-frailty was 52.6%, increased with age (p=0.001), and was greater in men than women (p=0.044). No relationship was found between pre-frailty and positive CMV serology. Further, CMV-seropositivity was significantly associated with less naïve cells, more memory and senescence-prone phenotypes (all p<0.001). After adjusting for potential confounders, only IL-6, age and sex were predictive of pre-frailty. We conclude that the presence of pre-frailty is independent from CMV infection in very old subjects.
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