J Clin Med Res

Journal of Clinical Medicine Research, ISSN 1918-3003 print, 1918-3011 online, Open Access

Article copyright, the authors; Journal compilation copyright, J Clin Med Res and Elmer Press Inc

Journal website https://jocmr.elmerjournals.com

Original Article

Volume 17, Number 4, April 2025, pages 187-199

Comparative Evaluation of Risk of Death in Mechanically Ventilated Patients With COVID-19 and Influenza: A Population-Based Cohort Study

Figure 1. Subgroup analysis of comparative short-term mortality among mechanically ventilated hospitalizations with COVID-19 and influenza. Analyses were conducted using overlap propensity score weighting. Adjusted risk ratio represents the risk of short-term mortality among mechanically ventilated hospitalizations with COVID-19 compared to those with influenza. Adjusted risk difference represents the absolute difference in short-term mortality among mechanically ventilated hospitalizations with COVID-19 compared to those with influenza, expressed as percentage. Non-parametric bootstrap 95% confidence intervals (CIs) were determined using 10,000 bootstrap samples and the percentile method. The width of the CIs was not adjusted for multiplicity and should not be used to infer definite effects. COVID-19: coronavirus disease 2019.

**Table 1.** The Characteristics and Outcomes of Mechanically Ventilated Hospitalizations With COVID-19 and Influenza
Variables	COVID-19^a	Influenza^a	P value
^aThe parenthesized figures represent percents, except for the Deyo comorbidity index and number of organ dysfunctions; percentage figures may not add to 100 due to rounding. ^bThe State of Texas suppresses gender data of hospitalizations with HIV infection, alcohol use, and substance use. ^cMean (standard deviation). ^dPost-acute care facilities include long-term acute care hospitals, inpatient rehabilitation, skilled nursing facilities, and nursing homes. COVID-19: coronavirus disease 2019; HIV: human immunodeficiency virus; ECMO: extracorporeal membrane oxygenation; Do-not-resuscitate: a do-not-resuscitate state.
Age, years			0.9212
18 - 44	2,252 (11.5)	285 (11.2)
45 - 64	6,612 (33.6)	861 (34.0)
≥ 65	10,795 (54.9)	1,390 (54.8)
Gender
Female	8,189 (41.7)	1,220 (48.1)	< 0.0001
Male	10,036 (51.1)	1,026 (40.6)
Suppressed^b	1,434 (7.3)	290 (11.4)
Race/ethnicity			< 0.0001
White	9,974 (50.7)	1,308 (51.6)
Hispanic	5,413 (27.5)	557 (22.0)
Black	2,755 (14.0)	504 (19.9)
Other	1,517 (7.7)	167 (6.6)
Health insurance			< 0.0001
Private	8,597 (43.7)	1,085 (42.8)
Medicare	6,909 (35.1)	846 (33.4)
Medicaid	1,383 (7.0)	238 (9.4)
Uninsured	1,688 (8.6)	297 (11.7)
Other	869 (4.4)	57 (2.2)
Missing	213 (1.1)	13 (0.5)
Deyo comorbidity index^c	2.04 (2.03)	2.53 (1.91)	< 0.0001
Comorbid conditions
Diabetes	8,341 (42.4)	990 (39.0)	0.0011
Liver disease	1,125 (5.7)	136 (5.4)	0.5386
Malignancy	1,272 (6.5)	145 (5.7)	0.1216
Congestive heart failure	6,639 (33.8)	1,231 (48.5)	< 0.0001
Chronic lung disease	5,597 (28.5)	1,463 (57.7)	< 0.0001
Myocardial infarction	2,998 (15.3)	475 (18.7)	< 0.0001
Peripheral vascular disease	715 (3.6)	107 (4.2)	0.1304
Dementia	1,509 (7.7)	163 (6.4)	0.0197
Peptic ulcer disease	303 (1.5)	33 (1.3)	0.4320
Hemiplegia/paraplegia	535 92.7)	46 (1.8)	0.0073
HIV	99 (0.5)	18 (0.7)	0.1882
Cerebrovascular disease	1,684 (8.6)	161 (6.3)	0.0001
Chronic renal disease	4,994 (25.4)	588 (23.2)	0.0163
Rheumatological disease	614 (3.1)	101 (4.0)	0.0154
Obesity	6,605 (33.6)	781 (30.8)	0.0049
Tobacco use	1,938 (9.9)	564 (22.2)	< 0.0001
Alcohol use	745 (3.8)	121 (4.8)	0.0145
Substance use	767 (3.9)	176 (6.9)	< 0.0001
Number of organ dysfunctions^c	2.60 (1.37)	2.13 (1.27)	< 0.0001
Hemodialysis	1,493 (7.6)	114 (4.5)	< 0.0001
ECMO	63 (0.3)	2 (0.07)	0.0369
Do-not-resuscitate	6,513 (33.1)	483 (19.0)	< 0.0001
Palliative care	4,348 (22.1)	318 (12.5)	< 0.0001
Teaching hospital	5,093 (25.9)	684 (27.0)	0.2348
Hospital admission period
Fourth quarter 2021	5,646 (28.7)	137 (5.4)	< 0.0001
First quarter 2022	7,792 (39.6)	305 (12.0)	< 0.0001
Second quarter 2022	716 (3.6)	261 (10.3)	< 0.0001
Third quarter 2022	2,267 (11.5)	101 (4.0)	< 0.0001
Fourth quarter 2022	1,281 (6.5)	1,230 (48.5)	< 0.0001
First quarter 2023	1,957 (10.0)	502 (19.8)	< 0.0001
Hospital disposition
In- hospital mortality	7,968 (40.5)	342 (13.5)	< 0.0001
Hospice	1,675 (8.5)	182 (7.2)	0.0259
Home	5,837 (29.7)	1,459 (57.5)	< 0.0001
Post-acute care facility^d	3,892 (19.8)	488 (19.2)	0.4749
Leave against medical advice	287 (1.5)	65 (2.6)	< 0.0001

Table 1. The Characteristics and Outcomes of Mechanically Ventilated Hospitalizations With COVID-19 and Influenza

Variables

COVID-19^a

Influenza^a

P value

N = 19,659

N = 2,536

^aThe parenthesized figures represent percents, except for the Deyo comorbidity index and number of organ dysfunctions; percentage figures may not add to 100 due to rounding. ^bThe State of Texas suppresses gender data of hospitalizations with HIV infection, alcohol use, and substance use. ^cMean (standard deviation). ^dPost-acute care facilities include long-term acute care hospitals, inpatient rehabilitation, skilled nursing facilities, and nursing homes. COVID-19: coronavirus disease 2019; HIV: human immunodeficiency virus; ECMO: extracorporeal membrane oxygenation; Do-not-resuscitate: a do-not-resuscitate state.

Age, years

0.9212

18 - 44

2,252 (11.5)

285 (11.2)

45 - 64

6,612 (33.6)

861 (34.0)

≥ 65

10,795 (54.9)

1,390 (54.8)

Gender

Female

8,189 (41.7)

1,220 (48.1)

< 0.0001

Male

10,036 (51.1)

1,026 (40.6)

Suppressed^b

1,434 (7.3)

290 (11.4)

Race/ethnicity

< 0.0001

White

9,974 (50.7)

1,308 (51.6)

Hispanic

5,413 (27.5)

557 (22.0)

Black

2,755 (14.0)

504 (19.9)

Other

1,517 (7.7)

167 (6.6)

Health insurance

< 0.0001

Private

8,597 (43.7)

1,085 (42.8)

Medicare

6,909 (35.1)

846 (33.4)

Medicaid

1,383 (7.0)

238 (9.4)

Uninsured

1,688 (8.6)

297 (11.7)

Other

869 (4.4)

57 (2.2)

Missing

213 (1.1)

13 (0.5)

Deyo comorbidity index^c

2.04 (2.03)

2.53 (1.91)

< 0.0001

Comorbid conditions

Diabetes

8,341 (42.4)

990 (39.0)

0.0011

Liver disease

1,125 (5.7)

136 (5.4)

0.5386

Malignancy

1,272 (6.5)

145 (5.7)

0.1216

Congestive heart failure

6,639 (33.8)

1,231 (48.5)

< 0.0001

Chronic lung disease

5,597 (28.5)

1,463 (57.7)

< 0.0001

Myocardial infarction

2,998 (15.3)

475 (18.7)

< 0.0001

Peripheral vascular disease

715 (3.6)

107 (4.2)

0.1304

Dementia

1,509 (7.7)

163 (6.4)

0.0197

Peptic ulcer disease

303 (1.5)

33 (1.3)

0.4320

Hemiplegia/paraplegia

535 92.7)

46 (1.8)

0.0073

HIV

99 (0.5)

18 (0.7)

0.1882

Cerebrovascular disease

1,684 (8.6)

161 (6.3)

0.0001

Chronic renal disease

4,994 (25.4)

588 (23.2)

0.0163

Rheumatological disease

614 (3.1)

101 (4.0)

0.0154

Obesity

6,605 (33.6)

781 (30.8)

0.0049

Tobacco use

1,938 (9.9)

564 (22.2)

< 0.0001

Alcohol use

745 (3.8)

121 (4.8)

0.0145

Substance use

767 (3.9)

176 (6.9)

< 0.0001

Number of organ dysfunctions^c

2.60 (1.37)

2.13 (1.27)

< 0.0001

Hemodialysis

1,493 (7.6)

114 (4.5)

< 0.0001

ECMO

63 (0.3)

2 (0.07)

0.0369

Do-not-resuscitate

6,513 (33.1)

483 (19.0)

< 0.0001

Palliative care

4,348 (22.1)

318 (12.5)

< 0.0001

Teaching hospital

5,093 (25.9)

684 (27.0)

0.2348

Hospital admission period

Fourth quarter 2021

5,646 (28.7)

137 (5.4)

< 0.0001

First quarter 2022

7,792 (39.6)

305 (12.0)

< 0.0001

Second quarter 2022

716 (3.6)

261 (10.3)

< 0.0001

Third quarter 2022

2,267 (11.5)

101 (4.0)

< 0.0001

Fourth quarter 2022

1,281 (6.5)

1,230 (48.5)

< 0.0001

First quarter 2023

1,957 (10.0)

502 (19.8)

< 0.0001

Hospital disposition

In- hospital mortality

7,968 (40.5)

342 (13.5)

< 0.0001

Hospice

1,675 (8.5)

182 (7.2)

0.0259

Home

5,837 (29.7)

1,459 (57.5)

< 0.0001

Post-acute care facility^d

3,892 (19.8)

488 (19.2)

0.4749

Leave against medical advice

287 (1.5)

65 (2.6)

< 0.0001

**Table 2.** Adjusted Analyses of the Comparative Short-Term Mortality^a Among Mechanically Ventilated Hospitalizations With COVID-19 Versus Influenza
Model^b	aRR (95% CI)^c	aRD^d (95% CI)^c
^aShort-term mortality is the composite of in-hospital death or discharge to hospice. ^bAll models were adjusted for patients’ sociodemographic characteristics, coexisting conditions, measures of severity of illness, organ support, use of palliative care, do-not-resuscitate status, hospitals’ teaching status, and year and calendar quarter of hospitalization. ^cNon-parametric bootstrap 95% CIs were determined using 10,000 bootstrap samples. ^dThe risk difference represents the absolute difference in risk of short-term mortality between mechanically ventilated hospitalizations with COVID-19 vs. those with influenza, expressed as percentage. COVID-19: coronavirus disease 2019; aRR: adjusted risk ratio; CI: confidence interval; aRD: adjusted risk difference.
Overlap propensity score weighting	1.24 (1.18 - 1.30)	8.8 (6.7 - 10.4)
Alternative analyses
Entropy balance	1.25 (1.19 - 1.33)	9.3 (7.4 - 11.7)
Hierarchical multivariable logistic regression	1.23 (1.22 - 1.34)	8.8 (8.3 - 12.0)

Table 2. Adjusted Analyses of the Comparative Short-Term Mortality^a Among Mechanically Ventilated Hospitalizations With COVID-19 Versus Influenza

Model^b

aRR (95% CI)^c

aRD^d (95% CI)^c

^aShort-term mortality is the composite of in-hospital death or discharge to hospice. ^bAll models were adjusted for patients’ sociodemographic characteristics, coexisting conditions, measures of severity of illness, organ support, use of palliative care, do-not-resuscitate status, hospitals’ teaching status, and year and calendar quarter of hospitalization. ^cNon-parametric bootstrap 95% CIs were determined using 10,000 bootstrap samples. ^dThe risk difference represents the absolute difference in risk of short-term mortality between mechanically ventilated hospitalizations with COVID-19 vs. those with influenza, expressed as percentage. COVID-19: coronavirus disease 2019; aRR: adjusted risk ratio; CI: confidence interval; aRD: adjusted risk difference.

Overlap propensity score weighting

1.24 (1.18 - 1.30)

8.8 (6.7 - 10.4)

Alternative analyses

Entropy balance

1.25 (1.19 - 1.33)

9.3 (7.4 - 11.7)

Hierarchical multivariable logistic regression

1.23 (1.22 - 1.34)

8.8 (8.3 - 12.0)