Table 2 Summary table of included studies

Aggar 2012* [25]

FFS

CRA

HADS

A set of comprehensive, multidisciplinary, and individualized interventions targeting frailty in CRs has some positive effects on CG burden.

CGs of CRs in the intervention group reported better health (F = 5.303, p = 0.023) and selfesteem than the control group (F = 4.158, p = 0.044). CGs in the intervention group showed continuous improvement in health scores over the duration of the study. Anxiety increased over time significantly in both intervention and control groups (F = 2.819, p = 0.04).

In secondary analysis, CGs who resided with CRs reported significantly higher self-esteem than non-co-resident CGs (F = 4.088, p = 0.046).

Cross-sectional (single point in time).

Risk of survey bias.

Outcomes of interest were not part of design of underlying RCT.

No subgroup analysis on frail vs. very frail subgroups.

Study population is relatively socioeconomically advantaged.

Study did not include any non-frail participants for comparison.

Comans 2011 [27]

No direct measure of frailty.

Potential proxy measures for components of FFS:

TUG, poor balance, use of walking aid (FFS; slow walking speed)

Low BMI (<24) and malnutrition (FFS; weight loss)

CSI

In an analysis of a small sample (N = 45) of caregiver/care recipient dyads, none of the potential proxy measures for slow walking speed or weight loss was significantly associated with caregiver strain.

Cross-sectional (single point in time).

No direct measure of frailty.

No subgroup analysis of CRs with and without CGs.

Relatively small sample size (45 of 107 CRs had CGs available).

Cullen 1997 [28]

No direct measure of frailty.

Potential proxy measures for component of FFS: gait ataxia; extrapyramidal gait disorder (FFS; slow walking speed)

RSS

In caregivers of cognitively impaired older adults, potential proxy measures of CRs’ slow walking speed were significantly associated with irritability and tension. Gait ataxia and extrapyramidal gait disorders were associated with caregiver irritability (p < 0.01, z-score = −1.60) and tension (p < 0.05, z-score = −1:36), respectively.

Neither gait disturbance was significantly associated with CG tiredness, worry, depression, or GHQ scale.

Cross-sectional (single point in time).

No direct measure of frailty.

Patient population is cognitively impaired; may not be representative of older adults generally.

CG burden variables were intercorrelated.

Faes 2011 [29]

All subjects had FFS ≥2.

No direct measure of frailty.

Potential proxy measures for component of FFS: TUG; walking velocity (FFS; slow walking speed)

ZBI

CES-D

HADS-A

EQ-5D-VAS

In this study of a multifactorial intervention to prevent falls in frail older adults, there was no significant difference between control and intervention groups in potential proxy measures of frailty (TUG or velocity).

There was no significant difference in any CG burden measure (including anxiety, depression, and quality of life) between CGs of CRs in the two groups.

No direct measure of frailty.

Small study population.

Study did not control for cognitive impairment.

Study did not include any non-frail participants for comparison (i.e., all participants had FFS ≥2).

Kim 2008 [30]

CGs in the “frail elderly” group reported that they were caring for someone who was “frail due to age.”

Frailty not otherwise defined.

Self-reported physical strain, emotional stress, and financial hardship as rated on a 5-point scale (1 = not at all; 5 = great deal/very much).

Self-reported amount of money spent on caregiving/mo.

Compared to three other groups of CGs (for patients with cancer, diabetes, and dementia), CGs of CRs whom the CGs themselves described as “frail due to age” reported the least physical strain, emotional stress, and financial hardship.

Of the four groups of CGs, carers of frail older adults also spent the least of their own money on caring and less than half the average time on caregiving activities.

Cross-sectional study (single point in time).

Risk of survey bias.

No direct measure of frailty; relied on CGs’ subjective impression of “frailty due to age,” which may have no relationship with physical frailty.