Abstract
Longevity has increased the proportion of the elderly in the population, and as a result ageing has become the leading factor for diseases such as cerebrovascular and cardiovascular disorders. It also makes surgical procedures more complex with potential life-threatening complications. In order to further investigate the role of ageing in modern healthcare, the term 'frailty' has been proposed to describe a condition of reduced functional reserve that leads to an increased risk of adverse health outcomes. The aim of this study was to review the pathophysiology of frailty and to highlight the most important tools to diagnose it, and their ability to predict the postoperative outcome. There are two major conceptual models that provide guidance for the detection of frailty: the Fried Phenotype Model and the Cumulative Deficit Model. These two main models have provided a base from which the assessment of frailty has developed. Two frailty assessment tools, the modified frailty index and the simplified frailty index play a key role in the preoperative setting because of their predictive power for postoperative risk quantification. Assessments of independence and/or cognitive function represent the main components that an ideal frailty tool should have to identify elderly people who are at risk of postoperative functional and cognitive deterioration. Cognitive impairment undoubtedly has a high association with frailty, but cognitive status is not included in many frailty assessments. In this regard, comprehensive geriatric assessment is a more complete evaluation tool, and it should be used whenever a frailty tool screening gives a positive result. Finally, frailty assessment is useful to explore the cumulative effect of comorbidities on the ageing patients' functional reserves and to identify the appropriate level of in-hospital and postdischarge care.