Current and future directions in frailty research.

The concept of frailty has been evolving dramatically for the past 30 years. Through its evolution, a variety of single and multidimensional models have been used to describe frailty. This article reviews the current literature related to the defining dimensions of frailty and identifies the gaps in the literature requiring additional research. A detailed literature review was performed to identify key dimensions and models currently being used to define frailty, classify interventions that have been developed to reverse frailty, and identify potential areas for future research within this field. Despite the large body of research defining the dimensions of frailty, no consensus exists on a comprehensive, operational definition. A standardized definition will be critical to design effective interventions at earlier stages along the continuum of frailty and interpret findings from evaluation studies. Identified gaps in the literature include studies supporting the utility of expanding the definition of frailty to incorporate social determinants, studies evaluating the role of obesity in the development of frailty, and the need for longitudinal studies for defining the pathways to developing frailty. This review highlights the need for an accurate definition of frailty and for longitudinal research to explore the development of frailty and evaluate the effectiveness of the frailty reversal interventions that may avert or delay adverse outcomes within this susceptible population. These future research needs are discussed within the context of the growing pressures to bring down health care costs, and the role of comparative effectiveness research and cost-effectiveness research in identifying interventions with the potential to help slow the growth of health care spending among the elderly.