Frailty Syndrome in older adults results from cumulative declines in several physiological systems, decreasing energy reserve and resistance to stressors.1,2 This condition has become very common and important in the geriatric setting, as it increases the risk of functional decline and deterioration in overall health status.3

Frailty Syndrome affects about 5.2 to 23.5% of older adult population,4, 5, 6 it may still be present in more than 50% of the longevous older adults (age 80 and over).7 Several studies have shown that this syndrome is a significant predictor of adverse outcomes, including falls, disability, institutionalization, and mortality, and that it also places increased pressure on the health care system because frail older adults are more likely to undergo hospitalization and require more critical care.1,8,9

Among the ways to identify the frailty syndrome in the older adult population, the frailty phenotype, defined by the presence of three or more of a total of five criteria, namely: unintentional weight loss; exhaustion; low muscle strength; low level of physical activity and slow gait, is one of the most used to classify the frail older adults.1

Several studies employing the Fried et al. phenotype have already shown that frailty is associated with age,4,10 functional impairment,4,10 cognitive decline,10 hospitalization,10 multimorbidity10 and self-perception of poor health.4 While many studies have examined factors associated with frailty using the Fried et al. phenotype, they only classified frailty based on the presence of three or more criteria. Thus, none of them investigated whether, when there are three or more criteria, there are those that tend to occur in clusters and which characteristics are associated with the existence of the syndrome with random criteria (without cluster) and with clusters of three and four criteria.

However, identifying which phenotype criteria are more prevalent in the syndrome may aid in improving our understanding of this condition by exploring the variety of interactions between its components, which will greatly assist us in selecting the most effective treatment. Understanding, in turn, which characteristics are associated with the clusters of three and four criteria of the phenotype may help in the decision about possible early interventions more appropriate.

Moreover, this research has an unprecedented character and is relevant to the targeting of more personalized and early population interventions, reducing the adverse consequences associated with frailty syndrome, reducing health care costs linked to frailty among older adults, and thereby ensuring improvements in the quality of life of older adults. Therefore, this study aims to identify the main clusters of diagnostic criteria pertaining to frailty syndrome as well as the factors associated with the occurrence of frailty without diagnostic criteria clusters and with clusters of three and four criteria.