In the following section, only the three key frailty measures selected for the final analyses (objective 3, section 6.6) are discussed. A subsequent section (section 6.4) will include
discussion of the five original frailty measures considered and the reasons for selecting the three key measures. With a few exceptions, the three key frailty measures considered were observed to be significantly associated with many of the same resident-level characteristics. The following are notable exceptions: CHESS vulnerability was not associated with increasing age or strength of social relationships, while the Full FI and CHSrel were; and CHSrel was not associated with cognitive function or aggressive behaviour, while the other frailty measures were.
The differences in resident-level correlates of the three frailty measures likely reflect the differing methods of assessing and identifying frailty. Frailty status defined by the Full FI was associated with almost every resident characteristic considered (with the exception of sex), perhaps because many of the characteristics considered are closely related to items in the Full FI
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(see Appendix C). The association between the Full FI and a variety of resident characteristics is also consistent with the frailty index conceptualization of frailty as the accumulation of deficits across numerous domains.
There was no association between CHSrel frailty and cognitive impairment, or aggressive behaviour (which is frequently associated with dementia in continuing care populations). The absence of an association between CHSrel frailty and cognition-related characteristics may be explained by the items assessed in the CHS measure, which focus on physical and (to a certain extent) psychological items (e.g., questions for the exhaustion item, which are derived from a depression scale) to define frailty, without inclusion of items assessing cognition (see Appendix E). A 2007 study by Rockwood and colleagues174 also reported that cognition was more highly correlated with the FI than with CHS, when using a different measure of cognition (3MS).
In contrast, the CHESS measure includes items related to physical function, disease status and cognition, but does not include any psychological or social items (see Appendix F), which may explain the absence of an association between CHESS and strength of social relationships. CHESS vulnerability was also observed to not be associated with age, unlike the other frailty measures. This is consistent with previous studies using CHESS, which showed a weak
correlation between age and CHESS score.88 This lack of association with age may be related to the fact that CHESS items are focused on acute measures of health instability (e.g., vomiting, changes in decision making or activity level over the past 90 days), which may make this
measure more relevant to recent changes in health status that accompany disease, than it is to the slower progression of frailty related to accumulation of deficits or a changing phenotype over longer periods of time.
124 6.2.2 Frailty, Depression and Dementia
In a recent editorial, 91 Hubbard offered evidence that dementia and depression frequently coexist, along with frailty in older adults. She suggests that each of these three conditions is also likely to put older adults at greater risk for the development of the other two conditions.
Analyses were carried out in order to examine the extent to which depression and dementia coexist with frailty, as defined by different frailty measures of interest.
For the purpose of the analysis underlying the Venn diagrams presented in section 5.2.2, ‘frail’ residents were restricted to those who had been classified as frail, and pre-frail residents were grouped with non-frail. Unlike the analyses for objective 3 (where frail and pre-frail residents were collapsed together because we wished to capture a broader range of vulnerability in relation to drug use and hospitalization risk), for the examination of coexisting dementia, depression and frailty, we were primarily interested in considering the condition or state of ‘being frail’ as specifically defined by the measures used.
The highest proportion of residents were identified as having frailty, depression and dementia when frailty was classified by the Armstrong FI. However, since the Armstrong FI identified more individuals as ‘frail’ than any of the other frailty measures, the higher degree of overlap across the three conditions may not reflect that Armstrong FI frailty coexists most often with the other two conditions. Indeed, of all of the frailty measures, the Armstrong FI classified the second highest number of residents with neither depression nor dementia as frail.
Frail residents, as classified by the Full FI, more frequently also had at least one of the two other conditions when compared to residents classified as frail by the other measures. Additionally, the
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Full FI classification system resulted in the fewest total residents classified as only frail, without having either of the other two conditions.
There was moderate overlap between CHESS frailty and the other two conditions, with an equivalent proportion of frail residents having either depression or dementia as was observed using the Armstrong FI.
Regardless of the frailty measure used, there was always a higher proportion of frail residents with depression than frail residents without depression. However, using either CHS measure, there was a higher proportion of frail residents without dementia than frail residents with dementia. This may be explained by the fact that the CHS measure does not include any items pertaining to cognition, as explained above. Using the two CHS measures, the lowest proportion of residents identified as frail also had either dementia or depression, when compared to the other frailty measures.
It is not surprising that frailty, as defined by the FI, more frequently co-exists with dementia and depression when compared to frailty, as defined by CHS. Although the CHS measure includes an exhaustion item, which may serve as a marker of depression, it is mostly focused on physical or phenotypic decline. There are no items assessing cognition in the CHS measure. The FI, in contrast, focusing on accumulation of deficits across numerous domains, includes items related to cognitive and psychosocial concerns. In fact, according to the FI conceptualization of frailty, depression and dementia would be items that, when combined with other deficits, could lead to a state of frailty.
It is clear that depending on the measure used to classify frailty, the extent to which the condition co-exists with dementia and depression will vary. In order to understand the complex interplay
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between these three conditions, it will be important to carefully consider the specific frailty measure used, and thus the conceptualization of frailty that is being investigated.