Archives of Academic Emergency Medicine. 2023; 11(1): e16 OR I G I N A L RE S E A RC H Associated Factors of In-hospital Mortality among Intu- bated Older Adults in Emergency Department; a Cross- sectional Study Mohd Idzwan Zakaria1, Norhadila Che Manshor2, Tan Maw Pin1∗ 1. Academic Trauma and Emergency Unit, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia. 2. Geriatric Unit, Department of Medicine, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia. Received: November 2022; Accepted: December 2022; Published online: 3 January 2023 Abstract: Introduction: A decision-making guideline on when to intubate an older person based on predictors of intubation outcome would be extremely beneficial. This study aimed to identify the associated factors that could predict the out- comes of endotracheal intubation among older adults in the Emergency Department (ED). Methods: In this retrospec- tive cross-sectional study, patients aged ≥65 years intubated at the ED of University of Malaya Medical Centre, Kuala Lumpur, Malaysia, from 2015 to 2019 were studied. The association between age, gender, place of inhabitation, Identifi- cation of Seniors at Risk (ISAR) score for frailty, Charlson Comorbidity Index (CCI), Acute Physiology and Chronic Health Evaluation-II (APACHE-II) score, indication for intubation, and diagnosis on admission with in-hospital mortality (pri- mary outcome) and duration of ventilation, and length of stay (secondary outcomes) were evaluated using univariate analysis and Cox’s regression survival analysis. Results: 889 cases aged 65 years and above were studied (61.5% male). The rate of in-hospital mortality was 71.4%. There was a significant association between age (p < 0.001), nursing home residency (p = 0.008), CCI≥ 5 (p = 0.001), APACHE-II (p < 0.001), pre-intubation Glasgow Coma Scale (GCS) (p < 0.001), cardiac arrest as indication of intubation (p < 0.001), diagnosis on admission (p < 0.001), length of stay (p < 0.001), and length of ventilation (p = 0.003) and in-hospital mortality. Age ≥ 85 years (HR= 1.270; 95%CI=1.074 to 1.502) and 75 to 84 years (HR=1.642; 95%CI=1.167 to 2.076), cardiac arrest as indication of intubation (HR: 1.882; 95% CI: 1.554 – 2.279), and APACHE-II scores 25 – 34 (HR: 1.423; 95% CI: 1.171 - 1.730) and ≥ 35 (HR: 1.789; 95%CI: 1.418 - 2.256) were amongst the independent predictive factors of in-hospital mortality. Conclusion: Nearly three out of four individuals aged ≥65 years intubated at the ED died during the same admission. Older age, cardiac arrest as indication of intubation, and APACHE-II score were independent predictors of in-hospital mortality. Keywords:Aged; intubation; emergency service, hospital; Respiration, Artificial Cite this article as: Idzwan Zakaria M, Che Manshor N, Maw Pin T. Associated Factors of In-hospital Mortality among Intubated Older Adults in Emergency Department; a Cross-sectional Study. Arch Acad Emerg Med. 2023; 11(1): e16. https://doi.org/10.22037/aaem.v11i1.1613. 1. Introduction Population ageing is occurring faster in low- to middle- income countries than high-income countries (1). In 2020, the number of older adults aged 65 years and above has in- creased to 7.0% of the total Malaysian population, compared to 6.7% in 2019. By 2030, older adults are expected to make up more than 15% of the Malaysian population (2). This de- mographic shift has been attributed to improved nutrition and sanitation, increasing life expectancy, and declining fer- ∗Corresponding Author: Tan Maw Pin; Geriatric Unit, Department of Medicine, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia. Email: mptan@ummc.edu.my, Tel: +60163328600, Fax: +60379492030, ORCID: https://orcid.org/0000-0002-3400-8540. tility rates (3). Advancements in medical science have led to improved crit- ical care and surgical management. While critical care man- agement regularly involves ventilatory support, such life- sustaining treatment in some individuals, particularly those in the older age group, may not necessarily lead to survival benefits (4). The decision whether to perform endotracheal intubation and artificial ventilation among older adults presenting with respiratory compromise in the emergency department (ED) is highly challenging. A retrospective cohort study by Ouchi et al. suggested that one in three older adults intubated in the emergency department died in hospital (5). A study by Foerch et al. mentioned that a quarter of intubated older stroke patients survived with good neurological outcome and This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Downloaded from: https://journals.sbmu.ac.ir/aaem/index.php/AAEM/index M. Idzwan Zakaria et al. 2 reasonable quality of life (6). In a cross-sectional stratified random national survey, Steinhouser et al. stated that more than 70% of older adults would choose quality of life above longevity (7). Despite this, the intubation rate for critically ill older adults has increased by 30% from 2001 to 2011 and fur- ther doubled by 2020 (8). A decision-making guideline on when to intubate an older person based on predictors of intubation outcome would be extremely beneficial. Therefore, this study aimed to evalu- ate the in-hospital mortality rate and its associated factors among older adults who received endotracheal intubation and ventilation at the ED. 2. Methods 2.1. Study design and setting This retrospective cross-sectional study was conducted on patients aged ≥65 years intubated at the ED of University of Malaya Medical Centre (UMMC), Kuala Lumpur, Malaysia, from 2015 to 2019. The association between age, gender, place of inhabitation, Identification of Seniors at Risk (ISAR) score for frailty, Charlson Comorbidity Index (CCI), Acute Physiology and Chronic Health Evaluation-II (APACHE-II) score, indication for intubation, and diagnosis on admission with in-hospital mortality, duration of ventilation, and length of stay were evaluated. The UMMC is a large teaching hospi- tal with a total of 1100 beds. It receives 1.1 million visits annu- ally with a 70-75% bed occupancy rate. The ED itself receives 25,000 older patients a year. Ethical approval was obtained from the University of Malaya Medical Center Medical Re- search Ethics Committee (MREC ID No: 2020224-8310). The researchers adhered to the confidentiality of patients’ pro- files and ethical considerations in biomedical research. 2.2. Participants All patients aged 65 years and above attending the ED who re- ceived endotracheal intubation were identified from the hos- pital electronic medical records (EMR) using the ICD-10 pro- cedural code for "Insertion of Endotracheal Airway into Tra- chea, via Natural or Artificial Opening” and included in the study. Those intubated outside the hospital, before arrival to hospital, and in the hospital ward were excluded. The list ob- tained was cross-checked with the Medical Records Depart- ment. 2.3. Data gathering Data was extracted from the EMR system using a standard- ized data collection document. Information on age (9), gender, place of inhabitation (home, nursing home or oth- ers) (10), the Identification of Seniors at Risk (ISAR) score for frailty (11), the Charlson Comorbidity Index (CCI) on admission (12), the Acute Physiology and Chronic Health Evaluation-II (APACHE-II) score (13, 14), the Glasgow Coma Scale (GCS) before intubation (15), indications for intuba- tion, and diagnosis on admission (16-18), was retrieved. The ISAR is a six-item tool, which quantifies frailty using com- monly measured variables in the ED (19). The responses are dichotomized as “yes” or “no”, and for each “yes” answer one point is allocated. Those with a score ≥2 out of 6 were consid- ered “at risk” of adverse outcomes. The Charlson Comorbid- ity Index (CCI) estimates the risk of death and is calculated by adding up weighed scores assigned to its 19 items, which are then summed up to a total score that ranges from 0–33. A to- tal score of ≥5 was considered to show high risk of death (20). The APACHE-II score assigns scores of 0-4 to 11 physiological measurements, including temperature, blood pressure, heart rate, respiratory rate, arterial pH, arterial oxygen saturation, serum sodium, serum potassium, serum creatinine, hemat- ocrit, and white cell count, in addition to 0-6 to age and 2 or 5 for chronic health points (21). The GCS score is added to the sum of scores to obtain a maximal total score of 71. A total APACHE-II score of ≥ 35 indicates a mortality risk of 80%. 2.4. Outcomes The primary outcome was in-hospital mortality, and the secondary outcomes were the duration of ventilation, and length of hospital stay. The date of death was obtained through the hospital EMR. 2.5. Statistical analysis Data analysis was carried out with the Statistical Package for Social Sciences software (SPSS, Chicago, IL, USA) version 22.0. The univariate association between each potential pre- dictor and the primary outcome was analyzed using the chi- square test. The Cox’s proportional hazards regression was used to develop a predictor model for time to hospital death. Hazard ratios (HR) and 95% confidence intervals (CI) were reported. Variables with a p-value < 0.05 in the univariate analyses and variables of clinical significance were selected for inclusion. 3. Results 3.1. Baseline characteristics of participants Eight hundred and eighty-nine individuals aged 65 years and above were intubated at the studied ED from 2015 to 2019 (7.5% ≥ 85 years and 61.5% male). Baseline characteristics of studied cases are summarized in table 1. 8% were nursing home residents. 424 (52 %) patients had a CCI of ≥ 5, while 660 (74%) patients had an ISAR score of ≥ 2, and 203 (23%) cases had an APACHE-II score of ≥ 35. A total of 316 (36%) patients had a pre-intubation GCS of 3. Of the 889 included individuals, 220 (25%) underwent crash intubation for car- diac arrest. This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Downloaded from: https://journals.sbmu.ac.ir/aaem/index.php/AAEM/index 3 Archives of Academic Emergency Medicine. 2023; 11(1): e16 Table 1: Baseline characteristics of intubated elder adults in emer- gency department (ED) Variable Value (%) Age (years) 65 – 74 505 (56.8) 75 – 84 317 (35.7) ≥ 85 67 (7.5) Gender Male 547 (61.5) Female 342 (38.5) Origin before ED visit Nursing home 68 (7.6) Others 821 (92.4) Charlson Comorbidity Index (CCI) < 5 465 (52.3) ≥ 5 424 (47.7) Identification of Seniors at Risk (ISAR) < 2 229 (25.8) ≥ 2 660 (74.2) APACHE-II Score 10 – 24 336 (37.8) 25 – 34 350 (39.4) ≥ 35 203 (22.8) Pre-intubation Glasgow coma scale (GCS) 15 204 (22.9) 4 – 14 369 (41.5) 3 316 (35.5) Indication of intubation Cardiac arrest 220 (24.7) Other 669 (75.3) Admission diagnosis Cardiac arrest 220 (24.7) Sepsis/septic shock 142 (16.0) ACS/heart failure 79 (8.9) Pneumonia 89 (10.0) Cerebrovascular accident 88 (9.9) Traumatic Brain Injury 51 (5.7) Others 220 (24.7) APACHE-II: Acute Physiology and Chronic Health Evaluation -II; ACS: acute coronary syndrome. 3.2. Univariate analysis Of all intubated older adults, 635 (71.4%) died in the hospi- tal. Table 2 summarizes the univariate analysis of factors as- sociated with in-hospital mortality. There were a significant association between age (p < 0.001), nursing home residency (p = 0.008), CCI≥ 5 (p = 0.001), APACHE-II score (p < 0.001), pre-intubation GCS (p < 0.001), cardiac arrest as indication of intubation (p < 0.001), diagnosis on admission (p < 0.001), length of stay (p < 0.001), and length of ventilation (p = 0.003) and in-hospital mortality of intubated older adults in emer- gency department. 3.3. Predictors of in-hospital mortality Age ≥ 85 years (HR= 1.270; 95%CI=1.074 to 1.502) and 75 to 84 years (HR=1.642; 95%CI=1.167 to 2.076), cardiac arrest as in- dication of intubation (HR: 1.882; 95% CI: 1.554 – 2.279), and APACHE-II scores 25 – 34 (HR: 1.423; 95% CI: 1.171 - 1.730) and ≥ 35 (HR: 1.789; 95%CI: 1.418 - 2.256) were amongst the independent predictive factors of in-hospital mortality among intubated older adults in emergency department. 4. Discussion The management of the critically ill older adults, especially in the intensive care unit is resource heavy with a correspond- ing increase in healthcare cost burden (22, 23). Hence, early decision making on the risk-benefit of intubation and venti- lation of critically ill older persons in the emergency depart- ment is paramount. In this study, nearly three out of four individuals aged 65 years and over intubated in the ED died in hospital. If only those aged 85 years and above were considered, the inpa- tient mortality rate was 90%. This proportion was far higher than that reported by a similar study conducted in a devel- oped country, which reported a mortality rate of 33% (5). While this discrepancy could be accounted for by better pre- hospital and critical care (24), an alternative explanation could also be the far higher caseloads handled in the ED in developing countries with patients presenting at a later stage of illness (25). This is also supported in a study in China and Iran during the COVID-19 pandemic, in which critically ill older persons had a significantly higher mortality rate than those younger(26, 27). Another possible explanation was the lack of validated criteria or risk scoring on the selection of pa- tients who might benefit from critical care as supported by a study in India (28). However, our study supported the poorer outcome of older persons aged more than 85 years old as re- ported by Bertrain Guidet et al. (29). Providing care for older patients does not mean subjecting them to aggressive treatments, such as intubation, which may lead to avoidable suffering to the patients and their families, and unnecessarily burdening the healthcare system (30). Previously published data have reported high mortality following adult out-of-hospital or in-hospital cardiac arrest (18, 31), but little is known about the effect of most inter- ventions during cardiac arrest, including drugs and the use of advanced airway management. In a study involving adult patients with in-hospital cardiac arrest, the initiation of tra- cheal intubation within the first 15 minutes of resuscitation, compared with no intubation, was associated with decreased survival to hospital discharge (18). Within this study, older adults who underwent emergency crash intubation during a cardiac arrest event had a higher inpatient mortality, high- lighting the potential futility of intubation in the majority of This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Downloaded from: https://journals.sbmu.ac.ir/aaem/index.php/AAEM/index M. Idzwan Zakaria et al. 4 Table 2: Comparing the characteristics of patients between survived and non-survived cases who were intubated in emergency department Predictors In-hospital mortality p-value Yes (n = 635) No (n = 254) Age (year) 65 – 74 328 (65.0) 117 (35.0) < 0.001 75 – 84 247 (77.9) 70 (22.1) ≥ 85 60 (89.6) 7 (10.4) Gender Male 379 (69.3) 168 (30.7) 0.074 Nursing home Yes 58 (85.3) 10 (14.7) 0.008 CCI ≥ 5 Yes 326 (76.9) 98 (23.1) 0.001 ISAR ≥ 2 Yes 477 (72.3) 183 (27.7) 0.344 APACHE-II 10 – 24 193 (57.4) 143 (42.6) 25 – 34 260 (74.3) 90 (25.7) < 0.001 ≥ 35 182 (89.7) 21 (10.3) Pre-intubation GCS 15 121 (59.3) 83 (40.7) 4 – 14 249 (67.5) 120 (32.5) < 0.001 3 265 (83.9) 51 (16.1) Indication of intubation Cardiac arrest 200 (90.9) 20 (9.1) < 0.001 Admission diagnosis Cardiac arrest 200 (90.9) 20 (9.1) Sepsis, septic shock 116 (81.7) 26 (18.3) ACS/heart failure 55 (69.6) 24 (30.4) < 0.001 Pneumonia 60 (67.4) 29 (32.6) Stroke/ICH 67 (76.1) 21 (23.9) Traumatic Brain Injury 37 (72.5) 14 (27.5) Others 100 (45.5) 120 (54.5) Duration of ventilation (week) < 1 438 (75.1) 145 (24.9) 1-2 159 (63.6) 91 (36.4) 0.003 >4 38 (67.9) 18 (32.1) Length of hospital stay (week) < 1 435 (96.5) 16 (3.5) 1-4 154 (48.7) 162 (51.3) < 0.001 > 4 46 (37.7) 76 (62.3) Data are presented as number (%). CCI: Charlson Comorbidity Index; ISAR: Identification of Seniors at Risk; APACHE-II: Acute Physiology and Chronic Health Evaluation-II; GCS: Glasgow coma scale; ACS: acute coronary syndrome; ICH: intracranial hemorrhage. older adults who suffer cardiac arrest in the hospital. How- ever, this does not necessarily advocate blanket avoidance of artificial ventilation in all older adults with cardiac arrest in hospital, and further research is required to ensure that the minority who will survive to discharge are not deprived of life saving treatment and are accurately identified. The APACHE-II score has long been established as an accu- rate measure of mortality among critically ill individuals (13, 14, 32). However, it has yet to be evaluated as a measure for survival following intubation in older patients. Within this study, the APACHE-II emerged as an independent predictor of in-hospital mortality. Although presence of comorbidi- ties was associated with inpatient mortality within the uni- variate analysis, it did not emerge within the final predictor model. Multiple studies have identified poorer outcomes in critically ill older adults with more underlying comorbidities (12, 20, 33). This has led to the common practice among health care workers, using comorbidities to facilitate end-of- life decisions for critically ill older adults. Our findings im- ply that the influence of comorbidity on inpatient mortality This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Downloaded from: https://journals.sbmu.ac.ir/aaem/index.php/AAEM/index 5 Archives of Academic Emergency Medicine. 2023; 11(1): e16 Table 3: Independent predictors of in-hospital mortality among intubated older adults in emergency department based on Cox’s Regression Survival Analysis Predictors B Hazard Ratio (95% CI) Age ( Years) 65 – 74 (reference) 75 – 84 0.239 1.270 (1.074 - 1.502) ≥ 85 0.496 1.642 (1.167 - 2.076) Indication of intubation Cardiac arrest 0.632 1.882 (1.554 – 2.279) APACHE-II score 10 – 24 25 – 34 0.353 1.423 (1.171 - 1.730) ≥ 35 0.582 1.789 (1.418 - 2.256) CI: confidence interval; APACHE-II: Acute Physiology and Chronic Health Evaluation-II. is accounted for by severity of illness, and the latter should be considered as the determinant of likelihood of survival to dis- charge rather than the former in the context of older adults who are intubated. Numerous frailty assessment tools have been developed based on adverse outcomes, which included mortality and hospitalization. A previous study found that critically ill frail patients have higher in-hospital mortality than non-frail patients, and the frail survivors were also more likely to become functionally dependent (34). The Identifica- tion of Senior at Risk (ISAR) tool has been developed as an identifier of those at high risk of adverse health outcomes after an Emergency Department visit. However, within this study, when applied within the context of intubation, frailty identified with the ISAR did not predict survival to discharge. Our finding, therefore, suggests that once an older individual is intubated, the likelihood of survival is determined by sever- ity of illness rather than frailty status before admission, but age alone still plays a significant role in influencing outcomes of artificial ventilation. This does imply that frailty measured using the ISAR tool does not predict intubation outcomes and is not an appropriate tool to aid decisions against intu- bation in older adults (35). This does not conform with other studies advocating the use of frailty scores as a modality of estimating outcome (29). A possible explanation is that ISAR has a poor to fair predictive validity in prediction of outcome and should not be use alone for identifying older persons at risk of adverse outcome in the emergency department (36). Decisions to withhold life-sustaining treatment such as en- dotracheal intubation are often challenging for medical pro- fessionals, with various cultural and religious views poten- tially influencing such decisions (37). Appropriate training for healthcare professionals on medical ethics and commu- nication skills may help reduce the burden of delivery of life- prolonging treatment that is likely to be futile, and this could be additionally facilitated with guidelines and decision aids. 5. Limitation This study is limited by its retrospective design, with poten- tial inaccuracies associated with retrospective data collec- tion such as misinterpretation of records in the EMR. It was not possible to verify the accuracy of the predictor scores recorded within the EMR. Nevertheless, the issue of high in- patient mortality rates in those intubated in the ED within our setting has been clearly highlighted, with important eth- ical and resource implications. Future studies should inves- tigate the reasons underlying this high mortality rate, as well as develop accurate predictor tools to aid decision making. In addition, evaluation of the role of ethics and communi- cation training, guidelines, and decision aids should also be considered in this regard. 6. Conclusion Age ≥ 75, cardiac arrest as indication for intubation, and APACHE-II scores ≥ 25 were independent predictive fac- tors of in-hospital mortality following intubation of older adults in the ED. Frailty and comorbidities evaluated with the ISAR tool and CCI, respectively, were not predictors of in- hospital mortality, challenging the existing practice of using pre-hospitalization frailty status and comorbidity burden to guide decision for or against intubation. 7. Declarations 7.1. Acknowledgments The authors are grateful to the medical records department and the staff at the Department of Emergency Medicine, UMMC for facilitating data collection. 7.2. Authors’ contributions Mohd Idzwan and Tan Maw Pin designed the protocol on methodology, ethical approval, writing, review and editing the manuscript. Mohd Idzwan also supervised the comple- This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Downloaded from: https://journals.sbmu.ac.ir/aaem/index.php/AAEM/index M. Idzwan Zakaria et al. 6 tion of the manuscript. Nor Hadila was involved in research literature review, gaining ethical approval, sample collection, data analysis, writing and editing the manuscript. All authors reviewed and edited the manuscript and approved the final version of the manuscript. 7.3. Funding and supports This was an unfunded study. 7.4. Conflict of interest None declared. 7.5. Availability of data The datasets generated and analyzed during the current study are available from Mohd Idzwan bin Zakaria. References 1. Shetty P. Grey matter: ageing in developing countries. Lancet. 2012;379(9823):1285-7. 2. Current population estimates, Malaysia, 2020 [press re- lease]. Department of Statistics Malaysia, 15th July 2020. https://www.dosm.gov.my/v1/index.php?r=column/pdf Prev&id=OVByWjg5YkQ3MWFZRTN5bDJiaEVhZz09#:te xt=Malaysia’s%20population%20in%202020%20is,to%20 3.0%20million%20(2020). 3. Mafauzy M. The problems and challenges of the aging population of malaysia. Malays J Med Sci. 2000;7(1):1-3. 4. Welie JV, Ten Have HA. The ethics of forgoing life- sustaining treatment: theoretical considerations and clinical decision making. Multidiscip. Respir. Med. 2014;9(1):1-8. 5. Ouchi K, Jambaulikar GD, Hohmann S, George NR, Aaronson EL, Sudore R, et al. Prognosis after emer- gency department intubation to inform shared decision- making. J Am Geriatr Soc J. 2018;66(7):1377-81. 6. Foerch C, Kessler K, Steckel D, Steinmetz H, Sitzer M. Sur- vival and quality of life outcome after mechanical ven- tilation in elderly stroke patients. J. Neurol. Neurosurg. Psychiatry. 2004;75(7):988-93. 7. Steinhauser KE, Christakis NA, Clipp EC, McNeilly M, McIntyre L, Tulsky JA. Factors considered important at the end of life by patients, family, physicians, and other care providers. JAMA. 2000;284(19):2476-82. 8. Lagu T, Zilberberg MD, Tjia J, Pekow PS, Lindenauer PK. Use of mechanical ventilation by patients with and without dementia, 2001 through 2011. JAMA Intern Med. 2014;174(6):999-1001. 9. Feng Y, Amoateng-Adjepong Y, Kaufman D, Gheorghe C, Manthous CA. Age, duration of mechanical ventilation, and outcomes of patients who are critically ill. Chest. 2009;136(3):759-64. 10. Wang R, Mouliswar M, Denman S, Kleban M. Mortality of the institutionalized old-old hospitalized with congestive heart failure. Arch. Intern. Med. 1998;158(22):2464-8. 11. Salvi F, Morichi V, Grilli A, Lancioni L, Spazzafumo L, Polonara S, et al. Screening for frailty in elderly emergency department patients by using the Identifi- cation of Seniors At Risk (ISAR). J. Nutr. Health Aging. 2012;16(4):313-8. 12. Song SE, Lee SH, Jo E-J, Eom JS, Mok JH, Kim M-H, et al. The prognostic value of the Charlson’s comorbidity index in patients with prolonged acute mechanical ven- tilation: a single center experience. Tuberc Respir Dis. 2016;79(4):289-94. 13. Qiao Q, Lu G, Li M, Shen Y, Xu D. Prediction of outcome in critically ill elderly patients using APACHE II and SOFA scores. J. Int. Med. Res. 2012;40(3):1114-21. 14. Kleinpell RM, Ferrans CE. Factors influencing intensive care unit survival for critically ill elderly patients. Heart & lung. 1998;27(5):337-43. 15. Broos P, D’Hoore A, Vanderschot P, Rommens P, Stap- paerts K. Multiple trauma in elderly patients. Factors in- fluencing outcome: importance of aggressive care. In- jury. 1993;24(6):365-8. 16. Seneff MG, Zimmerman JE, Knaus WA, Wagner DP, Draper EA. Predicting the duration of mechanical venti- lation: the importance of disease and patient character- istics. Chest. 1996;110(2):469-79. 17. George N, Jambaulikar GD, Sanders J, Ouchi K. A time- to-death analysis of older adults after emergency depart- ment intubation. J. Palliat. Med. 2020;23(3):401-5. 18. Andersen LW, Granfeldt A, Callaway CW, Bradley SM, Soar J, Nolan JP, et al. Association between tracheal in- tubation during adult in-hospital cardiac arrest and sur- vival. JAMA. 2017;317(5):494-506. 19. McCusker J, Bellavance F, Cardin S, Trepanier S, Verdon J, Ardman O. Detection of older people at increased risk of adverse health outcomes after an emergency visit: the ISAR screening tool. J Am Geriatr Soc. 1999;47(10):1229- 37. 20. Charlson ME, Pompei P, Ales KL, MacKenzie CR. A new method of classifying prognostic comorbidity in longitu- dinal studies: development and validation. J Chronic Dis. 1987;40(5):373-83. 21. Knaus WA, Draper EA, Wagner DP, Zimmerman JE. APACHE II: a severity of disease classification system. Crit Care Med. 1985;13(10):818-29. 22. Chin-Yee N, D’Egidio G, Thavorn K, Heyland D, Kyere- manteng K. Cost analysis of the very elderly admitted to intensive care units. Crit Care. 2017;21(1):1-7. 23. Angus DC. Admitting elderly patients to the in- tensive care unit—is it the right decision? JAMA. 2017;318(15):1443-4. This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Downloaded from: https://journals.sbmu.ac.ir/aaem/index.php/AAEM/index 7 Archives of Academic Emergency Medicine. 2023; 11(1): e16 24. de Carvalho IA, Epping-Jordan J, Pot AM, Kelley E, Toro N, Thiyagarajan JA, et al. Organizing integrated health-care services to meet older people’s needs. Bull World Health Organ. 2017;95(11):756. 25. Mohd Mokhtar MA, Pin TM, Zakaria MI, Hairi NN, Ka- maruzzaman SB, Vyrn CA, et al. Utilization of the emer- gency department by older residents in Kuala Lumpur, Malaysia. Geriatr Gerontol Int. 2015;15(8):944-50. 26. Yang X, Yu Y, Xu J, Shu H, Liu H, Wu Y, et al. Clinical course and outcomes of critically ill patients with SARS- CoV-2 pneumonia in Wuhan, China: a single-centered, retrospective, observational study. Lancet Respir Med. 2020;8(5):475-81. 27. Sanie Jahromi MS, Aghaei K, Taheri L, Kalani N, Hatami N, Rahmanian Z. [Intensive Care Unit of COVID-19 dur- ing the Different Waves of Outbreaks in Jahrom, South of Iran]. J Med Chem Sci. 2022; 5(5): 734-742. Persian 28. Chopra S, Pednekar S, Karnik ND, Londhe C, Pandey D. A Study of the Outcome of Critically Ill Elderly Patients in a Tertiary Care Hospital Using SOFA Score. Indian J Crit Care Med. 2021;25(6):655. 29. Guidet B, Vallet H, Boddaert J, de Lange DW, Morandi A, Leblanc G, et al. Caring for the critically ill patients over 80: a narrative review. Ann Intensive Care. 2018;8(1):1-15. 30. Cardona M, Turner RM, Chapman A, Alkhouri H, Lewis ET, Jan S, et al. Who benefits from aggressive rapid re- sponse system treatments near the end of life? A ret- rospective cohort study. Jt Comm J Qual Patient Saf. 2018;44(9):505-13. 31. Hirlekar G, Karlsson T, Aune S, Ravn-Fischer A, Alberts- son P, Herlitz J, et al. Survival and neurological outcome in the elderly after in-hospital cardiac arrest. Resuscita- tion. 2017;118:101-6. 32. Wu AW, Rubin HR, Rosen MJ. Are elderly people less responsive to intensive care? J Am Geriatr Soc. 1990;38(6):621-7. 33. Ferrante LE, Pisani MA, Murphy TE, Gahbauer EA, Leo- Summers LS, Gill TM. Functional trajectories among older persons before and after critical illness. JAMA In- tern Med. 2015;175(4):523-9. 34. Bagshaw SM, Stelfox HT, McDermid RC, Rolfson DB, Tsuyuki RT, Baig N, et al. Association between frailty and short-and long-term outcomes among critically ill pa- tients: a multicentre prospective cohort study. CMAJ. 2014;186(2):E95-E102. 35. Wilkinson DJ. Frailty triage: is rationing intensive med- ical treatment on the grounds of frailty ethical? Am J Bioeth. 2021;21(11):48-63. 36. Yao J-L, Fang J, Lou Q-Q, Anderson RM. A systematic re- view of the identification of seniors at risk (ISAR) tool for the prediction of adverse outcome in elderly patients seen in the emergency department. Int J Clin Exp Med. 2015;8(4):4778. 37. El Jawiche R, Hallit S, Tarabey L, Abou-Mrad F. Withhold- ing and withdrawal of life-sustaining treatments in inten- sive care units in Lebanon: a cross-sectional survey of in- tensivists and interviews of professional societies, legal and religious leaders. BMC Med Ethics. 2020;21(1):1-11. This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Downloaded from: https://journals.sbmu.ac.ir/aaem/index.php/AAEM/index Introduction Methods Results Discussion Limitation Conclusion Declarations References