In general frailty refers to ‘older adults or aged individuals who are lacking in general strength and are unusually susceptible to disease or to other infirmity’ [
1]. However, a diversity of conceptualizations of frailty have been proposed in the literature, ranging from a physical performance model [
2] to a multidimensional model [
3,
4] through conceptualizations of frailty as a medical syndrome [
5,
6], a geriatric syndrome [
7], or as deficit accumulation [
8]. Also, a systematic review examined operational definitions of frailty and identified 15 components in the different conceptualizations and screening tools for frailty (e.g. physical function, mobility, cognition) that were included in the review [
9]. Given the lack of consensus on a definition of frailty as well as criteria to identify or ‘diagnose’ frailty, estimates of prevalence are limited and highly variable, ranging from 4–59 % depending on the population being studied [
5,
10‐
15]. Regardless, the number of frail older adults will increase as the population continues to age [
6,
16], which has important implications for health systems given that those who are frail have greater risks of disabilities in basic and instrumental activities of daily living [
17,
18], chronic illnesses [
17,
19], greater reliance on in-home services [
20], hospitalization [
20,
21], institutionalization [
22,
23], and premature mortality [
23‐
25]. Therefore, as a result of population ageing, adverse consequences of frailty, and large social costs and burden for families and caregivers, there is a need to identify effective interventions to prevent or delay the onset as well as decrease the burden of frailty symptoms among older adults. Aiming such efforts at both pre-frail and frail older adults represents an opportunity for preventing or delaying the onset of frailty for those most at risk, improving the effectiveness of prevention and the delivery of care, and improving the health and quality of life for individuals with complex health needs.
Previous reviews have focused on interventions targeting frailty, but they address specific interventions, such as screening tools [
26], home-based support [
27], home telecare [
28], hospital discharge planning [
29], physical activity programmes [
30], or health promotion [
31]. Although these specific interventions are important individually, addressing frailty likely requires a comprehensive approach involving coordination across a broad range of interventions at clinical, public health, and system levels. To our knowledge, no reviews have synthesized findings across the entire spectrum of interventions aimed at pre-frail and frail older persons. In addition to this gap, there is a lack of consensus on what constitutes frailty due to a broad range of conceptualizations that are currently used [
16,
32‐
40]. It is unclear whether the different conceptualizations (e.g. syndrome vs. accumulation deficit) are associated with different intervention strategies (e.g. enhancing physical capacities vs. coping strategies).