Mahesh Chandra1, Vibhuti Sharma2, Santvana Kohli3, Ankita Yadav4, Surabhi Sandill5, Harish C. Sachdeva6
Author affiliations:
Background and Objective: COVID-19 has been associated with more than 770 million cases and 6.9 million deaths worldwide, since the first case was reported in 2019 in Wuhan, China. Various demographic and clinical factors have been associated with high mortality. We retrospectively analyzed data of patients admitted to our Intensive Care Unit (ICU) with moderate to severe disease for association of mortality with baseline clinical parameters and lab values.
Methodology: Retrospectively, data was collected for patients admitted to ICU of our hospital from March 2021 to August 2021, with moderate to severe covid infection. A total of 399 patients were included in the analysis after exclusion of patients with incomplete outcome data. Analysis was initially performed to find association of baseline parameters with ICU mortality; stratified analysis was further performed for association with various age groups.
Results: There was significant association of increased mortality with higher baseline heart rate (> 100 bpm), respiratory rate (> 30 bpm), low PaO2/FiO2 (< 100), Low oxygen saturation (< 80%), high neutrophil/lymphocyte ratio (> 10) and high baseline proBNP (> 500); however, subgroup analysis in the study showed that increased respiratory rate and increased neutrophil/lymphocyte ratio were not associated with increased mortality in patients with ages less than 50 y.
Conclusion: Baseline higher baseline heart rate, respiratory rate, low PaO2/FiO2, Low oxygen saturation, high neutrophil/lymphocyte ratio and high baseline proBNP were found to be associated with higher mortality in COVID patients. However, higher respiratory rate and higher neutrophil/lymphocyte ratio were not associated with increased mortality in patients with age less than 50 y.
Keywords: COVID-19, Heart rate, Respiratory rate, oxygen saturation, neutrophil/lymphocyte ratio, proBNP
Citation: Chandra M, Sharma V, Kohli S, Yadav A, Sandill S, Sachdeva HC. Analysis of clinical risk factors in COVID-19 mortality in ICU in various age groups: A retrospective observational study. Anaesth. pain intensive care 2024;28(2):278−284; DOI: 10.35975/apic.v28i2.2323
Received: October 16, 2024; Reviewed: January 18, 2024; Accepted: February 20, 2024
Corona virus disease2019 which originated in Wuhan, China was a global pandemic causing major health concern all over the world.1 It was caused by SARS COV-2 virus affecting primarily the respiratory system. The clinical manifestations varied from mild self-limiting disease to life threatening multiple organ involvement. It affected all age groups with significant morbidity and mortality rate and adverse outcomes becoming a global burden. 2
Initially it was thought to involve respiratory symptoms, pneumonia and in severe cases progressing to ARDS requiring hospitalization. But now it is known to cause systemic inflammation affecting multiple organs including lung, heart, blood vessels, CNS, and other systems.
A systematic review of patients admitted in COVID ICU of our hospital was conducted. The aim of the study was to identify clinical predictors at the time of admission associated with mortality of COVID-19 patients of different age groups in our hospital admitted in intensive care unit during second wave.
After getting clearance from Institutional ethics committee, data of moderate to severe COVID-19 patients admitted to our hospital from March 2021 till August 2021 was initially collected for analysis of epidemiological and clinical risk factors associated with the mortality in COVID-19 patients. Patients were excluded from this study if outcome data was unavailable, and 399 eligible patients were included in the study. The medical records of the patients were then retrospectively reviewed and data regarding heart rate (HR), respiratory rate (RR), oxygen saturation (SpO2), partial pressure of oxygen, oxygen support, Neutrophil/Lymphocyte (N/L) ratio and Brain Natriuretic Peptide (BNP) at time of admission was collected for analysis.
Our primary predictor of interest was ICU mortality. Calculation of risk of death according to baseline values was done using Chi-square test. Stratified analysis was also performed using Chi-square test to calculate odds of mortality in various age groups (less than 50 y, 50-70 y, and more than 70 y).
A total of 399 patients admitted in our ICU during second wave of COVID were included in this study with an overall mortality of 232 (58.1%).
A baseline HR of more than 100 bpm at the time of admission was associated with a higher mortality (78.4%) compared to those with lower baseline HR (47.9%) (Figure 1). χ2 (1, N = 399) = 33.871, P ≤ .001.
Stratified analysis in age groups of less than 50 y, 50-70 y and more than 70 y revealed that the mortality difference was maintained in different age groups (Table 1).
A baseline RR of more than 30 bpm at the time of admission was associated with higher mortality (73.9%) compared to those with lower RR (51.1%) (Figure 2). χ2 (1, N = 393) = 17.792, P ≤ .001.
A baseline RR of more than 30 bpm at the time of admission was associated with higher mortality (73.9%) compared to those with lower RR (51.1%) (Figure 2).
χ2 (1, N = 393) = 17.792, P ≤ .001.
However stratified analysis of age groups revealed that the increased RR was only associated with increased mortality in patients with age more than 50 y, and no significant difference was found in those with age less than 50 y (45.9% vs 49.5%) (Table 2). χ2 (1, N = 130) = .131, P = .717.
Hence increased RR might not be a prognostic marker in lower age groop patients.
A baseline PO2/FiO2 ratio of less than 100 at the time of admission was associated with a higher mortality (68.9%) compared to those with higher PO2/FiO2 ratio (41.2%) (Figure 3).
χ2 (1, N = 391) = 29.411, P ≤ .001.
Stratified analysis in age groups also revealed similar mortality differences however the results in individual age groups could not achieve statistical significance due to low number (Table 3).
A baseline oxygen saturation of less than 80 at the time of admission was associated with a higher mortality (83.5%) compared to those with higher oxygen saturation (42.2%) (Figure 4). χ2 (1, N = 276) = 45.09, P ≤ .001.
Stratified analysis in age groups also revealed similar mortality differences (Table 4).
A baseline N/L ratio of more than 10 at the time of admission was associated with a higher mortality (66.1%) compared to those with lower N/L ratio (49.5%) (Figure 5). χ2 (1, N = 272) = 5.303, P ≤ .021.
However, stratified analysis in age groups revealed that increase N/L ratio was only associated with increased mortality in patients with age more than 50 y and no significant difference was found in those with age less than 50 y (38.7% vs 37.5%) (Table 5). χ2 (1, N = 91) = .008, P ≤ .931.
Hence increased N/L ratio might not be a prognostic marker in lower age grp patients.
A baseline BNP of more than 500 at the time of admission was associated with a higher mortality (68.4%) compared to those with lower baseline BNP (43.2%) (Figure 6). χ2 (1, N = 209) = 13.275, P ≤ .001.
Stratified analysis in age groups also revealed similar mortality differences however statistical significance could not be achieved due to low number (Table 6).
COVID-19 was associated with a large impact on healthcare worldwide with many clinical risk factors studied for impact on mortality. In our study we analyzed the clinical risk factors in various age groups and their association with mortality.
A baseline HR of more than 100 bpm was associated with higher mortality in our study. Similar findings have been reported in a study conducted by Han Jin et al. on 136 patients in China, which showed significantly higher mortality among patients with tachycardia (HR > 100 bpm) as compared to those with moderate HR (80-90 bpm) and low HR (< 80 bpm).3 However, study conducted by Ahmed Sameer Ikram et al. showed that there was no significant difference in admission HR between survivors and non survivors.4 Age wise analysis in our study revealed that increased HR was associated with increased mortality in all age groups.
A baseline RR of more than 30 bpm was associated with increased mortality. Similar findings were found by many authors.4-8 However subgroup analysis in our study revealed that it was significant only in patients with more than 50 y of age and that in younger age group increased RR was not a very reliable marker for mortality prediction.
A baseline PaO2/FiO2 < 100 is also known to be associated with increased moratlity.9-10 Similar findings were there in our study with a low PaO2/FiO2 ratio associated with higher mortality in all age groups.
Low oxygen saturation is associated with increased mortality.4,11 Analysis of baseline oxygen saturation revealed that patients with baseline SpO2 < 80% had 83.5% mortality rate as compared to 42.5% in those with SpO2 > 80%. The mortality difference was maintained in all age groups studied. Similar findings were reported by Peter M. Mphekgwana et al. who showed greater mortality in patients with SpO2 < 95% in all age groups as compared to those with SpO2 > 95% (P = 0.006).12 Another study conducted by Fernando Mejia et al. showed that SpO2 value on admission was lower in deceased patients compared to discharged patients (78% vs 91% P < 0.001).13
A high neutrophil/lymphocyte ratio has been associated with increased mortality in COVID-19 patients.14-15 Similar results were found in our study but age group analysis further showed that high N/L ratio was only associated with increased mortality in patients more than 50 y old, with no significant association with mortality in lower age groups.
A high baseline proBNP levels have also been associated with increased mortality.16-18 Similar results were there in our study with mortality association in all age groups.
Increased baseline heart rate, respiratory rate, low PaO2/FiO2, low oxygen saturation, high neutrophil/lymphocyte ratio and high baseline proBNP levels are associate with increased mortality in COVID-19 patients; however, subgroup analysis in our study showed that increased respiratory rate and increased neutrophil/lymphocyte ratio were not associated with increased mortality in patients with ages less 50 y and further studies may be required.
6. Data availability
The numerical data generated during this research is available with the authors.
7. Preregistration
The study was registered with Clinical Trials Registry- India (CTRI), hosted at the ICMR's National Institute of Medical Statistics (https://icmr-nims.nic.in) with registration number CTRI/2022/02/040638
8. Source of Funding
The study utilized the hospital resources only, and no external or industry funding was involved.
9. Conflict of interest
The authors declare that there was no conflict of interest.
10. Authors’ contribution
MC, VS: Conduct of study; literature search; statistical analysis & manuscript editing
SK: Conduct of study; literature search; statistical analysis
AY, SS, HCS: Conduct of study; literature search
Author affiliations:
- Mahesh Chandra, Associate Professor, Department of Anesthesia & Intensive Care, Vardhman Mahavir Medical College & Safdarjung Hospital, New Delhi, Delhi 110029, India; ORCID: {0000-0002-1107-668X} E-mail: maheshhchandra@yahoo.in
- Vibhuti Sharma, Associate Professor, Department of Anesthesia & Intensive Care, Vardhman Mahavir Medical College & Safdarjung Hospital, New Delhi, Delhi 110029, India; ORCID: {0000-0002-5456-5854} E-mail: vibhuti411@gmail.com
- Santvana Kohli, Associate Professor, Department of Anesthesia & Intensive Care, Vardhman Mahavir Medical College & Safdarjung Hospital, New Delhi, Delhi 110029, India; ORCID: {0000-0003-1410-6933} E-mail: dr.santvana.kohli@gmail.com
- Ankita Yadav, Senior Resident, Department of Anesthesia & Intensive Care, Vardhman Mahavir Medical College & Safdarjung Hospital, New Delhi, Delhi 110029, India; E-mail: dr.ankitayadav28@gmail.com
- Surabhi Sandill, Senior Resident, Department of Anesthesia & Intensive Care, Vardhman Mahavir Medical College & Safdarjung Hospital, New Delhi, Delhi 110029, India; ORCID: {0000-0003-3533-5436} E-mail: surabhisandill@gmail.com
- Harish C. Sachdeva, Professor & Consultant, Department of Anesthesia & Intensive Care, Vardhman Mahavir Medical College & Safdarjung Hospital, New Delhi, Delhi 110029, India; ORCID: {0000-0003-4476-0506} E-mail: sachdeva_hc04@yahoo.com
ABSTRACT
Background and Objective: COVID-19 has been associated with more than 770 million cases and 6.9 million deaths worldwide, since the first case was reported in 2019 in Wuhan, China. Various demographic and clinical factors have been associated with high mortality. We retrospectively analyzed data of patients admitted to our Intensive Care Unit (ICU) with moderate to severe disease for association of mortality with baseline clinical parameters and lab values.
Methodology: Retrospectively, data was collected for patients admitted to ICU of our hospital from March 2021 to August 2021, with moderate to severe covid infection. A total of 399 patients were included in the analysis after exclusion of patients with incomplete outcome data. Analysis was initially performed to find association of baseline parameters with ICU mortality; stratified analysis was further performed for association with various age groups.
Results: There was significant association of increased mortality with higher baseline heart rate (> 100 bpm), respiratory rate (> 30 bpm), low PaO2/FiO2 (< 100), Low oxygen saturation (< 80%), high neutrophil/lymphocyte ratio (> 10) and high baseline proBNP (> 500); however, subgroup analysis in the study showed that increased respiratory rate and increased neutrophil/lymphocyte ratio were not associated with increased mortality in patients with ages less than 50 y.
Conclusion: Baseline higher baseline heart rate, respiratory rate, low PaO2/FiO2, Low oxygen saturation, high neutrophil/lymphocyte ratio and high baseline proBNP were found to be associated with higher mortality in COVID patients. However, higher respiratory rate and higher neutrophil/lymphocyte ratio were not associated with increased mortality in patients with age less than 50 y.
Keywords: COVID-19, Heart rate, Respiratory rate, oxygen saturation, neutrophil/lymphocyte ratio, proBNP
Citation: Chandra M, Sharma V, Kohli S, Yadav A, Sandill S, Sachdeva HC. Analysis of clinical risk factors in COVID-19 mortality in ICU in various age groups: A retrospective observational study. Anaesth. pain intensive care 2024;28(2):278−284; DOI: 10.35975/apic.v28i2.2323
Received: October 16, 2024; Reviewed: January 18, 2024; Accepted: February 20, 2024
1. INTRODUCTION
Corona virus disease2019 which originated in Wuhan, China was a global pandemic causing major health concern all over the world.1 It was caused by SARS COV-2 virus affecting primarily the respiratory system. The clinical manifestations varied from mild self-limiting disease to life threatening multiple organ involvement. It affected all age groups with significant morbidity and mortality rate and adverse outcomes becoming a global burden. 2
Initially it was thought to involve respiratory symptoms, pneumonia and in severe cases progressing to ARDS requiring hospitalization. But now it is known to cause systemic inflammation affecting multiple organs including lung, heart, blood vessels, CNS, and other systems.
A systematic review of patients admitted in COVID ICU of our hospital was conducted. The aim of the study was to identify clinical predictors at the time of admission associated with mortality of COVID-19 patients of different age groups in our hospital admitted in intensive care unit during second wave.
2. METHODOLOGY
After getting clearance from Institutional ethics committee, data of moderate to severe COVID-19 patients admitted to our hospital from March 2021 till August 2021 was initially collected for analysis of epidemiological and clinical risk factors associated with the mortality in COVID-19 patients. Patients were excluded from this study if outcome data was unavailable, and 399 eligible patients were included in the study. The medical records of the patients were then retrospectively reviewed and data regarding heart rate (HR), respiratory rate (RR), oxygen saturation (SpO2), partial pressure of oxygen, oxygen support, Neutrophil/Lymphocyte (N/L) ratio and Brain Natriuretic Peptide (BNP) at time of admission was collected for analysis.
| Table 1: Mortality rates in different age groups: Significant mortality association was found in all age groups with increased HR. | |||
| Age group | HR < 100 bpm | HR > 100 bpm | p |
| Less than 50 y (133) | 38.3% (31 deaths /81 patients) | 65.4% (34 deaths /52 patients) | .002 |
| 50-70 (196) | 47.4% (63 deaths /133 patients) | 84.1% (53 deaths/63 patients) | .001 |
| >70 (70) | 64.7% (33 deaths /51 patients) | 94.7% (18 deaths /19 patients) | .012 |
Our primary predictor of interest was ICU mortality. Calculation of risk of death according to baseline values was done using Chi-square test. Stratified analysis was also performed using Chi-square test to calculate odds of mortality in various age groups (less than 50 y, 50-70 y, and more than 70 y).
3. RESULTS
A total of 399 patients admitted in our ICU during second wave of COVID were included in this study with an overall mortality of 232 (58.1%).
A baseline HR of more than 100 bpm at the time of admission was associated with a higher mortality (78.4%) compared to those with lower baseline HR (47.9%) (Figure 1). χ2 (1, N = 399) = 33.871, P ≤ .001.
Stratified analysis in age groups of less than 50 y, 50-70 y and more than 70 y revealed that the mortality difference was maintained in different age groups (Table 1).
A baseline RR of more than 30 bpm at the time of admission was associated with higher mortality (73.9%) compared to those with lower RR (51.1%) (Figure 2). χ2 (1, N = 393) = 17.792, P ≤ .001.
| Table 2: Mortality rates in different age groups: Significant mortality association was not found in patients with age less than 50 y with increased respiratory rate (RR) | |||
| Age group | RR < 30 | RR > 30 | p |
| Less than 50 y (130) | 49.5% (46 deaths /93 patients) | 45.9% (17 deaths /37 patients) | .717 |
| 50-70 (194) | 47.4% (62 deaths /131 patients) | 84.1% (53 deaths /63 patients) | .001 |
| >70 (69) | 64.0% (32 deaths /50 patients) | 94.7% (18 deaths /19 patients) | .011 |
A baseline RR of more than 30 bpm at the time of admission was associated with higher mortality (73.9%) compared to those with lower RR (51.1%) (Figure 2).
χ2 (1, N = 393) = 17.792, P ≤ .001.
However stratified analysis of age groups revealed that the increased RR was only associated with increased mortality in patients with age more than 50 y, and no significant difference was found in those with age less than 50 y (45.9% vs 49.5%) (Table 2). χ2 (1, N = 130) = .131, P = .717.
Hence increased RR might not be a prognostic marker in lower age groop patients.
A baseline PO2/FiO2 ratio of less than 100 at the time of admission was associated with a higher mortality (68.9%) compared to those with higher PO2/FiO2 ratio (41.2%) (Figure 3).
χ2 (1, N = 391) = 29.411, P ≤ .001.
Stratified analysis in age groups also revealed similar mortality differences however the results in individual age groups could not achieve statistical significance due to low number (Table 3).
| Table 3: Mortality rates in different age groups: Similar mortality association was found in all age groups with low PO2/FiO2 ratios. | |||
| Age group | PO2/FiO2 > 100 | PO2/FiO2 < 100 | p |
| Less than 50 y (130) | 39.6% (21 deaths /53 patients) | 55.8% (43 deaths /77 patients) | .069 |
| 50-70 (194) | 37.2% (29 deaths /78 patients) | 73.3% (85 deaths /116 patients) | .001 |
| >70 (67) | 59.1% (13 deaths /22 patients) | 80% (36 deaths /45 patients) | .07 |
| Table 4: Mortality rates in different age groups: Significant mortality association was found in all age groups with decreased oxygen saturation | |||
| Age group | SpO2 > 80% | SpO2 < 80% | p |
| Less than 50 y (92) | 28.8% (17 deaths /59 patients) | 75.8% (25 deaths /33 patients) | .001 |
| 50-70 (132) | 44.3% (35 deaths /79 patients) | 83% (44 deaths /53 patients) | .001 |
| >70 (52) | 60% (21 deaths /35 patients) | 100% (17 deaths /17 patients) | .002 |
A baseline oxygen saturation of less than 80 at the time of admission was associated with a higher mortality (83.5%) compared to those with higher oxygen saturation (42.2%) (Figure 4). χ2 (1, N = 276) = 45.09, P ≤ .001.
Stratified analysis in age groups also revealed similar mortality differences (Table 4).
A baseline N/L ratio of more than 10 at the time of admission was associated with a higher mortality (66.1%) compared to those with lower N/L ratio (49.5%) (Figure 5). χ2 (1, N = 272) = 5.303, P ≤ .021.
However, stratified analysis in age groups revealed that increase N/L ratio was only associated with increased mortality in patients with age more than 50 y and no significant difference was found in those with age less than 50 y (38.7% vs 37.5%) (Table 5). χ2 (1, N = 91) = .008, P ≤ .931.
| Table 5: Mortality rates in different age groups: Significant mortality association was not found in patients with age less than 50 yrs. with increased N/L ratio. | |||
| Age group | N/L ratio < 10 | N/L ratio > 10 | p |
| Less than 50 y (91) | 38.7% (29 deaths /75 patients) | 37.5% (6 deaths /16 patients) | .931 |
| 50-70 (136) | 52.9% (54 deaths /102 patients) | 73.5% (25 deaths /34 patients) | .035 |
| >70 (45) | 63.6 (% 21 deaths /33 patients) | 83.3% (10 deaths /12 patients) | .207 |
| Table 6: Mortality rates in different age groups: Similar mortality association was found in all age groups with increased BNP | |||
| Age group | BNP < 500 | BNP > 500 | p |
| Less than 50 y (65) | 29.5% (13 deaths /44 patients) | 57.1% (12 deaths /21 patients) | .032 |
| 50-70 (103) | 46.7% (28 deaths /60 patients) | 65.1% (28 deaths /43 patients) | .064 |
| >70 (41) | 100% (7 deaths /7 patients) | 79.4% (27 deaths /34 patients) | .187 |
Hence increased N/L ratio might not be a prognostic marker in lower age grp patients.
A baseline BNP of more than 500 at the time of admission was associated with a higher mortality (68.4%) compared to those with lower baseline BNP (43.2%) (Figure 6). χ2 (1, N = 209) = 13.275, P ≤ .001.
Stratified analysis in age groups also revealed similar mortality differences however statistical significance could not be achieved due to low number (Table 6).
4. DISCUSSION
COVID-19 was associated with a large impact on healthcare worldwide with many clinical risk factors studied for impact on mortality. In our study we analyzed the clinical risk factors in various age groups and their association with mortality.
A baseline HR of more than 100 bpm was associated with higher mortality in our study. Similar findings have been reported in a study conducted by Han Jin et al. on 136 patients in China, which showed significantly higher mortality among patients with tachycardia (HR > 100 bpm) as compared to those with moderate HR (80-90 bpm) and low HR (< 80 bpm).3 However, study conducted by Ahmed Sameer Ikram et al. showed that there was no significant difference in admission HR between survivors and non survivors.4 Age wise analysis in our study revealed that increased HR was associated with increased mortality in all age groups.
A baseline RR of more than 30 bpm was associated with increased mortality. Similar findings were found by many authors.4-8 However subgroup analysis in our study revealed that it was significant only in patients with more than 50 y of age and that in younger age group increased RR was not a very reliable marker for mortality prediction.
A baseline PaO2/FiO2 < 100 is also known to be associated with increased moratlity.9-10 Similar findings were there in our study with a low PaO2/FiO2 ratio associated with higher mortality in all age groups.
Low oxygen saturation is associated with increased mortality.4,11 Analysis of baseline oxygen saturation revealed that patients with baseline SpO2 < 80% had 83.5% mortality rate as compared to 42.5% in those with SpO2 > 80%. The mortality difference was maintained in all age groups studied. Similar findings were reported by Peter M. Mphekgwana et al. who showed greater mortality in patients with SpO2 < 95% in all age groups as compared to those with SpO2 > 95% (P = 0.006).12 Another study conducted by Fernando Mejia et al. showed that SpO2 value on admission was lower in deceased patients compared to discharged patients (78% vs 91% P < 0.001).13
A high neutrophil/lymphocyte ratio has been associated with increased mortality in COVID-19 patients.14-15 Similar results were found in our study but age group analysis further showed that high N/L ratio was only associated with increased mortality in patients more than 50 y old, with no significant association with mortality in lower age groups.
A high baseline proBNP levels have also been associated with increased mortality.16-18 Similar results were there in our study with mortality association in all age groups.
5. CONCLUSIONS
Increased baseline heart rate, respiratory rate, low PaO2/FiO2, low oxygen saturation, high neutrophil/lymphocyte ratio and high baseline proBNP levels are associate with increased mortality in COVID-19 patients; however, subgroup analysis in our study showed that increased respiratory rate and increased neutrophil/lymphocyte ratio were not associated with increased mortality in patients with ages less 50 y and further studies may be required.
6. Data availability
The numerical data generated during this research is available with the authors.
7. Preregistration
The study was registered with Clinical Trials Registry- India (CTRI), hosted at the ICMR's National Institute of Medical Statistics (https://icmr-nims.nic.in) with registration number CTRI/2022/02/040638
8. Source of Funding
The study utilized the hospital resources only, and no external or industry funding was involved.
9. Conflict of interest
The authors declare that there was no conflict of interest.
10. Authors’ contribution
MC, VS: Conduct of study; literature search; statistical analysis & manuscript editing
SK: Conduct of study; literature search; statistical analysis
AY, SS, HCS: Conduct of study; literature search
11. REFERENCES
- Coronavirus Disease (COVID-19) Situation Reports; 2022. Available from: https://www.who.int/emergencies/diseases/novel-coronavirus-2019/situation-reports
- Huang C, Wang Y, Li X, Ren L, Zhao J, Hu Y, et al. Clinical features of patients infected with 2019 novel coronavirus in Wuhan, China. Lancet. 2020 Feb 15;395(10223):497-506. PMID: 31986264 DOI: 1016/S0140-6736(20)30183-5
- Jin H, Yang S, Yang F, Zhang L, Weng H, Liu S, et al. Elevated resting heart rates are a risk factor for mortality among patients with coronavirus disease 2019 in Wuhan, China. J Transl Int Med. 2021 Dec 31;9(4):285-293. PMID: 35136727 DOI: 2478/jtim-2021-0042
- Ikram AS, Pillay S. Admission vital signs as predictors of COVID-19 mortality: a retrospective cross-sectional study. BMC Emerg Med. 2022;22(1):68. PMID: 35488200 DOI: 1186/s12873-022-00631-7
- Gallo Marin B, Aghagoli G, Lavine K, Yang L, Siff EJ, Chiang SS, et al. Predictors of COVID-19 severity: A literature review. Rev Med Virol. 2021 Jan;31(1):1-10. PMID: 32845042 DOI: 1002/rmv.2146
- Petrilli CM, Jones SA, Yang J, Rajagopalan H, O'Donnell L, Chernyak Y, et al. Factors associated with hospital admission and critical illness among 5279 people with coronavirus disease 2019 in New York City: prospective cohort study. BMJ. 2020 May 22;369:m1966. PMID: 32444366 DOI: 1136/bmj.m1966
- Puah SH, Young BE, Chia PY, Ho VK, Loh J, Gokhale RS, et al. Clinical features and predictors of severity in COVID-19 patients with critical illness in Singapore. Sci Rep. 2021;11(1):7477. PMID: 33820944 DOI: 1038/s41598-021-81377-3
- Zhou S, Mi S, Luo S, Wang Y, Ren B, Cai L, et al. Risk Factors for Mortality in 220 Patients With COVID-19 in Wuhan, China: A Single-Center, Retrospective Study. Ear Nose Throat J. 2021;100(2_suppl):140S-147S. PMID: 33155834 DOI: 1177/0145561320972608
- Gu Y, Wang D, Chen C, Lu W, Liu H, Lv T, et al. PaO2/FiO2 and IL-6 are risk factors of mortality for intensive care COVID-19 patients. Sci Rep. 2021;11(1):7334. PMID: 33795768 DOI: 1038/s41598-021-86676-3
- Zinellu A, De Vito A, Scano V, Paliogiannis P, Fiore V, Madeddu G, et al. The PaO2/FiO2 ratio on admission is independently associated with prolonged hospitalization in COVID-19 patients. J Infect Dev Ctries. 2021;15(3):353-359. PMID: 33839709 DOI: 3855/jidc.13288
- Chatterjee NA, Jensen PN, Harris AW, Nguyen DD, Huang HD, Cheng RK, et al. Admission respiratory status predicts mortality in COVID-19. Influenza Other Respir Viruses. 2021;15(5):569-572. PMID: 34028169 PMCID: PMC8242415 DOI: 1111/irv.12869
- Mphekgwana PM, Sono-Setati ME, Maluleke AF, Matlala SF. Low Oxygen Saturation of COVID-19 in Patient Case Fatalities, Limpopo Province, South Africa. J Respir. 2022;2(2):77-86. DOI: 3390/jor2020006
- Mejía F, Medina C, Cornejo E, Morello E, Vásquez S, Alave J, et al. Oxygen saturation as a predictor of mortality in hospitalized adult patients with COVID-19 in a public hospital in Lima, Peru. PLoS One. 2020;15(12):e0244171. PMID: 33370364 DOI: 1371/journal.pone.0244171
- La Torre G, Marte M, Massetti AP, Carli SM, Romano F, Mastroianni CM, et al. The neutrophil/lymphocyte ratio as a prognostic factor in COVID-19 patients: a case-control study. Eur Rev Med Pharmacol Sci. 2022;26(3):1056-1064. PMID: 35179773 DOI: 26355/eurrev_202202_28017
- Toori KU, Qureshi MA, Chaudhry A, Safdar MF. Neutrophil to lymphocyte ratio (NLR) in COVID-19: A cheap prognostic marker in a resource constraint setting. Pak J Med Sci. 2021;37(5):1435-1439. PMID: 34475926 DOI: 12669/pjms.37.5.4194
- Caro-Codón J, Rey JR, Buño A, Iniesta AM, Rosillo SO, Castrejon-Castrejon S, et al. Characterization of NT-proBNP in a large cohort of COVID-19 patients. Eur J Heart Fail. 2021;23(3):456-464. PMID: 33421281 DOI: 1002/ejhf.2095
- Wang L, Chen F, Bai L, Bai L, Huang Z, Peng Y. Association between NT-proBNP Level and the Severity of COVID-19 Pneumonia. Cardiol Res Pract. 2021;2021:5537275. PMID: 34306746 PMCID: PMC8266470 DOI: 1155/2021/5537275
- Sorrentino S, Cacia M, Leo I, Polimeni A, Sabatino J, Spaccarotella CAM, et al. B-Type Natriuretic Peptide as Biomarker of COVID-19 Disease Severity-A Meta-Analysis. J Clin Med. 2020;9(9):2957. PMID: 32932743 DOI: 3390/jcm9092957