Discussion
multimorbidity, anxiety/depression, cardiovascular and neurological diseases, mood alterations, deficit, Frailty
RECRUITMENT, DISEASES
This study tracked five metrics, cognition, muscle strength, mood alterations, multimorbidity and functional capacity, which represent different aspects of frailty over a 1-year follow-up of aged care residents. The results suggest an interdependence between multimorbidity, muscle strength (as measured by grip strength), cognition (measured by MoCA) and functional capacity (measured as capacity to perform activities of daily living) in this population. Ageing and progressive morbidity affect multiple physiological systems and the results shine some light on the complex interaction of those systems over time in older people. The analysis systematically describe how frailty evolves in this usually frail population. In summary, the study shows that metrics were (1) uncorrelated at baseline, but (2) may predict future decline in other metrics, and (3) are associated within individuals, meaning the decline in one follows a decline in another.The tracked metrics were independent at baseline. Studies of community living individuals suggest that frailty measures are mostly independent in younger individuals [Baseline analysis and the influence on change at 12 months paint a somewhat complex picture, with multiple interactions between tracked metrics. A graphical summary of the relationships is shown in Fig. Finally, the study shows a strong within-individual association between all metrics but anxiety/depression score. Taken together, the results suggest that while the metrics are measuring different things (no correlation at baseline), they may trigger further decline and tend to converge over time. These findings are coherent with the systems theory of frailty [There are two practical implications of our findings. The first is supporting the concept of frailty as a dynamic decline in multiple physiological systems. The deficit accumulation approach posits that frailty is the accumulation of abnormal clinical features, such as cardiovascular and neurological diseases, leading to a state of decreased functional capacity and susceptibility to additional diseases [Overall, the data presented here suggest frailty is better described as a multidimensional concept over time than as a True/False statement. Frailty scales are a proxy of how well the different physiological systems are working, and may be more strongly associated with self-reported frailty than actual performance decline [The main strength of our study is the longitudinal follow up of older people. As residents in an aged care residence, some degree of impairment was present in all individuals. This cohort will benefit from improved frailty identification measures, for preventative and therapeutic measures to reverse frailty. The main limitation of our study is that it is a sub-study of an interventional clinical trial. The intervention may have altered the natural frailty course and introduced biases. To account for biases, we performed the analysis stratified by intervention or control group. While statistical significance was lost, the direction of associations was consistent in both groups. The relatively small sample size reduced the capacity for further stratification, such as by gender and age, and these variables should be included in future studies. The analysis stratified by intervention group can be found in the appendices. Enrolment criteria may also have introduced a bias which limits generalisability. Recruitment was exclusive for aged care residents but excluded participants with low MoCA and high frailty index. Since this is a population unable to live independently, there may be other factor not measured contributing to increased frailty over time. A cap effect in frailty index (both morbidity and function) meant people with higher frailty index (frail) were less likely to become frailer than individuals with low frailty index score (healthier). Finally, some measures might be inadequate as long term measures of patient function and require further studies with more detailed data collection.