Table 3.

Summary of included studies.

Author (Year), Country	Design	Sample and Setting	Outcomes	Quality of Evidence	Frailty Definition	ED Length of Stay (LOS) or Boarding Definition	Comments
García-Peña et al. (2018) [3], Mexico	Retrospective cohort study	≥60 years, ED N = 1406	Mortality at 120 days (21.7%), the length of stay (in hours) in the ED (4.8 h).	High	YES	YES	This study analyses all causes of death, and one factor associated with mortality that appears to be important is the length of stay in the ED. This variable was statistically significant in all analyses.
Cardona et al. (2018) [14], Australia	Prospective cohort study	≥65 years, ED N = 2493	90-days mortality (10.1% in Australia and 13.6% in Denmark) and ability of CriSTAL to predict in-hospital death.	Medium	YES	NR	This study analyses the deaths at 90 days in two cohorts (Australia and Denmark) and specifies that those who died in the hospital had a significantly longer mean length of stay than their counterpart who survived in both healthcare setting.
Aprahamian et al. (2019) [5], Brazil	Prospective cohort study	≥60 years, ED N = 316	Death at 6 months (16.5%), readmission to ED (17.4%).	High	YES	NR	Frailty was related to an odds ratio of 2.18 for mortality at 6 months (95% CI = 1.10–4.31; p = 0.024), even after adjusting for age and sex. This suggests that frailty may be a predictive factor for death.
Rauch et al. (2019) [11], Germany	Retrospective case-control study	≥75 years, ED N = 13,451	Examines differences in arrival rates for frail vs. non-frail patients in detail and comparision of case complexity (ED length of stay).	Low	YES	YES	Comparing frail and non-frail groups, they found significantly higher levels for all examined variables (including ED LOS) in frail patients.
Maarek et al. (2020) [15], France	Prospective observational study	≥75 years, ED N = 298	30-day all-cause mortality (6%), length of stay, and emergency readmission within 30 days of initial discharge.	High	YES	NR	Their study showed that the frail patient group, compared with the non-frail patient group, had a higher risk of death, hospital readmission, and LOS.
Liu et al. (2020) [6], China	Prospective cohort study	≥60 years, ED N = 350	All-cause 28-day mortality (9.4%), ADL Dependency, mechanical ventilation (9.7%), LOS in hospital, and ICU readmission 30 and 90 days after discharge (14.6% and 24%).	Medium	YES	NR	Their study showed that the frail patient group, compared with the non-frail patient group, had a higher risk of death, hospital readmission, and LOS.
Lewis et al. (2020) [2], United Kingdom	Cohort single-site study	≥75 years, ED N = 468	Mortality at 180 days, length of stay of >14 and > 28 days, inpatient mortality, and reattendance within 30, 120, and 180 days of discharge after admission.	Low	YES	NR	A positive Frailsafe predicts an increased risk of mortality, hospitalization, and a combined 180-day outcome of mortality and hospitalization.
Van Dam et al. (2021) [4], Netherlands	Prospective cohort study	≥70 years, ED N = 889	Functional decline (20%), institutionalization (11%), and mortality (10%).	Medium	YES	NR	This study confirms that older patients in ED are at higher risk of adverse outcomes and they considered prolonged length of stay as an outcome measure.
Rueegg et al. (2021) [16], Switzerland	Prospective single-centre observational Cohort study	≥65 years, ED N = 2191	1-year all-cause mortality (17%).	High	YES	NR	This study shows that higher frailty levels were associated with higher mortality.
Lin et al. (2021) [9], Taiwan	Prospective Before-and-after study	≥75 years, ED N = 358	Revisits to the ED (30.7%), admission for hospitalization (20.4%) and mortality within three months (5.6%).	High	YES	NR	Outcomes revealed that older patients with frailty had increased three-month mortality, higher ED use, longer length of stay, increased probability of hospitalization, and higher mortality.
Elliot et al. (2021), [7] United Kingdom	Retrospective single-centre cohort study	≥65 years, ED N = 52,562	Length of stay, readmission, mortality (24% at two years) and associations of the Clinical Frailty Scale at ED with negative outcomes.	High	YES	YES	They used the Clinical Frailty Scale at ED triage to assess the risk of adverse outcomes in older patients. Results showed that the Clinical Frailty Scale applied at a single point was strongly associated with the risk of increased hospital use and death, even after adjustment for prognostically important covariates. Cumulative postoperative days in the ED (>30 or 180 days) were associated with increasing Clinical Frailty Scale scores.
Kabell Nissen et al. (2022) [17], Switzerland	Prospective single-centre observational Cohort study	≥65 years, ED N = 2250	30-day mortality (5.4%).	High	YES	NR	This study shows that a simple assessment of frailty can give clinical information that has high clinical interaction with acute disease severity and may provide better support for clinical judgment in the ED regarding older patients.
Gaffney et al. (2022) [10], Ireland	Secondary analysis of a prospective cohort study	≥70 years, ED N = 191	Length of stay (LOS, 8 days), frailty deter- mined by CGA and one-year mortality (18%).	Medium	YES	NR	Study showed that a large number of older people presenting to the ED are SQ-test-positive and this is associated with frailty, hospital admission, prolonged length of stay, and death within a year.

Legend: NR = not reported, N = number of patients presenting at Emergency Department (ED), LOS = Length of stay, CGA = Comprehensive geriatric assessment, SQ = Surprise Question, ICU = Intensive Care Unit.