1. Mendes A, Serratrice C, Herrmann FR, et al. Predictors of In-Hospital Mortality in Older Patients with COVID-19: The COVIDAge Study. J Am Med Dir Assoc 2020; 21(11): 1546–1554.e3.
2.
Bavaro DF, Diella L, Fabrizio C, et al. Peculiar clinical presentation of COVID-19 and predictors of mortality in the elderly: a multicentre retrospective cohort study. Int J Infect Dis 2021; 105: 709–715.
3.
Zazzara MB, Penfold RS, Roberts AL, et al. Probable delirium is a presenting symptom of COVID-19 in frail, older adults: a cohort study of 322 hospitalised and 535 community-based older adults. Age Ageing 2021; 50(1): 40–48.
4.
Aliberti MJR, Szlejf C, Avelino‐Silva VI, et al. COVID‐19 is not over and age is not enough: using frailty for prognostication in hospitalized patients. J Am Geriatr Soc 2021; 69(5): 1116–1127.
5.
Andrés-Esteban EM, Quintana-Diaz M, Ramírez-Cervantes KL, et al. Outcomes of hospitalized patients with COVID-19 according to level of frailty. Peer J 2021; 9: e11260.
6.
Chong E, Chan M, Tan HN, et al. COVID‐19: Use of the Clinical Frailty Scale for Critical Care Decisions. J Am Geriatr Soc 2020; 68(6): E30–E32.
7.
Hoogendijk EO, Afilalo J, Ensrud KE, et al. Frailty: implications for clinical practice and public health. Lancet 2019; 394(10206): 1365–1375.
8.
Collard RM, Boter H, Schoevers RA, et al. Prevalence of frailty in community-dwelling older persons: a systematic review. J Am Geriatr Soc 2012; 60(8): 1487–1492.
9.
Kojima G. Prevalence of Frailty in Nursing Homes: A Systematic Review and Meta-Analysis. J Am Med Dir Assoc 2015; 16(11): 940–945.
10.
Sablerolles RSG, Lafeber M, Kempen JAL van, et al. Association between Clinical Frailty Scale score and hospital mortality in adult patients with COVID-19 (COMET): an international, multicentre, retrospective, observational cohort study. Lancet Healthy Longev 2021; 2(3): e163–e170.
11.
Owen RK, Conroy SP, Taub N, et al. Comparing associations between frailty and mortality in hospitalised older adults with or without COVID-19 infection: a retrospective observational study using electronic health records. Age Ageing 2021; 50(2): 307–316.
12.
Geriatric Medicine Research Collaborative, Covid Collaborative, et al. Age and frailty are independently associated with increased COVID-19 mortality and increased care needs in survivors: results of an international multi-centre study. Age Ageing 2021; 50(3): 617–630.
13.
The COVID-ICU investigators, Dres M, Hajage D, Lebbah S, et al. Characteristics, management, and prognosis of elderly patients with COVID-19 admitted in the ICU during the first wave: insights from the COVID-ICU study: prognosis of COVID-19 elderly critically ill patients in the ICU. Ann Intensive Care 2021; 11(1): 77.
14.
Miles A, Webb TE, Mcloughlin BC, et al. Outcomes from COVID-19 across the range of frailty: excess mortality in fitter older people. Eur Geriatr Med 2020; 11(5): 851–855.
15.
Gordon EH, Peel NM, Samanta M, et al. Sex differences in frailty: a systematic review and meta-analysis. Exp Gerontol 2017; 89: 30–40.
16.
Page MJ, McKenzie JE, Bossuyt PM, et al. The PRISMA 2020 statement: an updated guideline for reporting systematic reviews. BMJ 2021; n71.
17.
Wells GA, O’Connell D, Peterson J, et al. The Newcastle-Ottawa Scale (NOS) for assessing the quality of nonrandomised studies in meta-analyses [cited 10.06.2021]. Available from URL: http://www.ohri.ca/programs/clinical_epidemiology/oxford.asp.
18.
Dent E, Martin FC, Bergman H, et al. Management of frailty: opportunities, challenges, and future directions. Lancet 2019; 394(10206): 1376–1386.
19.
Rockwood K, Theou O. Using the Clinical Frailty Scale in Allocating Scarce Health Care Resources. Can Geri J 2020; 23(3): 254–259.
20.
Deek J, Higgins J, Altman D. Analysing data and undertaking meta-analysis. In: Cochrane handbook for systematic reviews of interventions. Hoboken, New Jersey: John Wiley & Sons Ltd; 2008.
21.
Hewitt J, Carter B, Vilches-Moraga A, et al. The effect of frailty on survival in patients with COVID-19 (COPE): a multicentre, European, observational cohort study. Lancet Public Health 2020; 5(8): e444–e451.
22.
Tehrani S, Killander A, Åstrand P, et al. Risk factors for death in adult COVID-19 patients: Frailty predicts fatal outcome in older patients. Int J Infect Dis 2021; 102: 415–421.
23.
Chinnadurai R, Ogedengbe O, Agarwal P, et al. Older age and frailty are the chief predictors of mortality in COVID-19 patients admitted to an acute medical unit in a secondary care setting – a cohort study. BMC Geriatr 2020; 20(1): 409.
24.
Neradova A, Vajgel G, Hendra H, et al. Frailty score before admission as risk factor for mortality of renal patients during the first wave of the COVID pandemic in London. G Ital Nefrol 2021; 38(3): 2021-vol3.
25.
Blomaard LC, Linden CMJ van der, Bol JM van der, et al. Frailty is associated with in-hospital mortality in older hospitalised COVID-19 patients in the Netherlands: the COVID-OLD study. Age Ageing 2021; 50(3): 631–640.
26.
Osuafor CN, Davidson C, Mackett AJ, et al. Clinical Features, Inpatient Trajectories and Frailty in Older Inpatients with COVID-19: A Retrospective Observational Study. Geriatrics 2021; 6(1): 11.
27.
Aw D, Woodrow L, Ogliari G, Harwood R. Association of frailty with mortality in older inpatients with Covid-19: a cohort study. Age Ageing 2020; 49(6): 915–422.
28.
Yang Y, Luo K, Jiang Y, et al. The Impact of Frailty on COVID-19 Outcomes: A Systematic Review and Meta-analysis of 16 Cohort Studies. J Nutr Health Aging 2021; 25(5): 702–709.
29.
Jain V, Yuan J-M. Predictive symptoms and comorbidities for severe COVID-19 and intensive care unit admission: a systematic review and meta-analysis. Int J Public Health 2020; 65(5): 533–546.
30.
Chen X, Mao G, Leng SX. Frailty syndrome: an overview. Clin Interv Aging 2014; 9: 433–441.
31.
Soysal P, Stubbs B, Lucato P, et al. Inflammation and frailty in the elderly: a systematic review and meta-analysis. Ageing Res Rev 2016; 31: 1–8.
32.
Jakubiak GK, Pawlas N, Cieślar G, et al. Chronic Lower Extremity Ischemia and Its Association with the Frailty Syndrome in Patients with Diabetes. IJERPH 2020; 17(24): 9339.
33.
Marengoni A, Zucchelli A, Vetrano DL, et al. Beyond Chronological Age: Frailty and Multimorbidity Predict In-Hospital Mortality in Patients with Coronavirus Disease 2019. J Gerontol A Biol Sci Med Sci 2021; 76(3): e38–e45.
34.
Pranata R, Henrina J, Lim MA, et al. Clinical frailty scale and mortality in COVID-19: A systematic review and dose-response meta-analysis. Arch Gerontol Geriatr 2021; 93: 104324.
35.
Jung C, Flaatten H, Fjølner J, et al. The impact of frailty on survival in elderly intensive care patients with COVID-19: the COVIP study. Crit Care 2021; 25(1): 149.
36.
Hägg S, Jylhävä J, Wang Y, et al. Age, Frailty, and Comorbidity as Prognostic Factors for Short-Term Outcomes in Patients with Coronavirus Disease 2019 in Geriatric Care. J Am Med Dir Assoc 2020; 21(11): 1555–1559.e2.
37.
Ramos‐Rincon J, Moreno‐Perez O, Pinargote‐Celorio H, et al. Clinical Frailty Score vs Hospital Frailty Risk Score for predicting mortality and other adverse outcome in hospitalised patients with COVID‐19: Spanish case series. Int J Clin Pract 2021; 75(10): e14599.
38.
Gebhard C, Regitz-Zagrosek V, Neuhauser HK, et al. Impact of sex and gender on COVID-19 outcomes in Europe. Biol Sex Differ 2020; 11(1): 29.
39.
Lithander FE, Neumann S, Tenison E, et al. COVID-19 in older people: a rapid clinical review. Age Ageing 2020; 49(4): 501–515.
40.
Bielza R, Sanz J, Zambrana F, et al. Clinical Characteristics, Frailty, and Mortality of Residents with COVID-19 in Nursing Homes of a Region of Madrid. J Am Med Dir Assoc 2021; 22(2): 245–252.e2.
41.
Saudi RA, Tosson EE, Salama HM. Association between frailty status and cognitive performance of elderly patients attending the Family Medicine Outpatient Clinic in Ismailia, Egypt. Fam Med Prim Care Rev 2021; 23(2): 232–238.
42.
Fagard K, Gielen E, Deschodt M, et al. Risk factors for severe COVID-19 disease and death in patients aged 70 and over: a retrospective observational cohort study. Acta Clin Belg 2021; 1–8, doi: 10.1080/17843286.2021.1890452.
43.
Bujnowska-Fedak MM, Waligóra J, D’Avanzo B, et al. Approaches to therapy and prevention of frailty in the light of contemporary medicine. Fam Med Prim Care Rev 2017; 19(3): 289–297.