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Annals of Intensive Care

Table 1 Demographic and clinical characteristics of patients with coronavirus disease 2019 under invasive mechanical ventilation therapy

From: Association between mortality and age among mechanically ventilated COVID-19 patients: a Japanese nationwide COVID-19 database study

Variables

Survivor

(n = 1128)

Non-survivor

(n = 401)

Standardized difference, %

Age, years

64.3 (12.3)

73.4 (9.9)

− 81.5

 Male

904/1126 (80.3)

306/401 (76.3)

9.72

 Body mass index ≥ 30

157/940 (16.7)

40/314 (12.7)

11.31

Admission date

 3rd wave (October 1st–)

484/1126 (43.0)

175/401 (43.6)

− 1.21

 2nd wave (June 1st, 2020–September 30, 2020)

258/1126 (22.9)

71/401 (17.7)

12.95

 1st wave (January 26, 2020–May 31, 2020)

384/1126 (34.1)

155/401 (38.7)

− 9.57

Race

 Japanese

1091/1120 (97.4)

391/395 (99.0)

− 12.06

Smoking history

527/866 (60.9)

177/288 (61.5)

− 1.23

Drinking history

432/709 (60.9)

121/229 (52.8)

16.41

Comorbidity

842/1128 (74.6)

336/401 (83.8)

− 22.81

 Hypertension

552/1128 (48.9)

193/401 (48.1)

1.60

 Diabetes

389/1128 (34.5)

158/401 (39.4)

− 10.16

 Hyperlipidemia

256/1128 (22.7)

97/401 (24.2)

− 3.54

 Cerebrovascular disease

97/1128 (8.6)

54/401 (13.5)

15.68

 COPD

71/1128 (6.3)

30/401 (7.5)

− 4.74

 Bronchial asthma

63/1128 (5.6)

19/401 (4.7)

4.07

 Solid tumor

50/1128 (4.4)

32/401 (8.0)

− 14.97

 Liver disease

46/1128 (4.1)

22/401 (5.5)

− 6.55

 Moderate-to-severe chronic kidney disease

41/1128 (3.6)

29/401 (7.2)

− 15.98

 Ischemic heart disease

41/1128 (3.6)

26/401 (6.5)

− 13.27

 Congestive heart failure

35/1128 (3.1)

25/401 (6.2)

− 14.76

 Major neurocognitive disorder

28/1128 (2.5)

28/401 (8.3)

− 25.88

 Chronic lung disease excluding COPD

28/1128 (2.5)

26/401 (6.5)

− 19.39

 Hemodialysis before admission

28/1128 (3.1)

22/401 (5.5)

− 11.85

 Collagen disease

19/1128 (1.7)

11/401 (2.7)

− 6.82

 Metastatic solid tumor

7/1128 (0.6)

7/401 (1.7)

− 10.33

 Lymphoma

7/1128 (0.6)

5/401 (1.2)

− 6.36

 Leukemia

0/1128 (0)

2/401 (0.5)

− 10.33

Immunosuppression

32/1091 (2.9)

23/384 (6.0)

0.01

Vital signs on admission

 AVPU scale A (Alert)

846/1021 (82.8)

281/366 (76.8)

14.99

 Fever (≥ 38 °C)

369/1121 (32.9)

110/397 (27.7)

11.33

 Respiratory rate ≥ 30 breaths/ minute

168/1011 (16.6)

61/359 (17.0)

− 1.07

 SpO2 < 90%

163/1114 (15.1)

71/391 (18.2)

− 8.33

 Systolic blood pressure ≤ 80 mmHg

20/1112 (1.8)

3/396 (0.8)

8.84

Symptoms at admission

1088/1102 (98.7)

378/387 (97.7)

7.53

  1. Analysis based on records from the COVID-19 Registry Japan. Data given as number of positive observations/total number of observations (percentage) or as mean (standard deviation). For each variable, the number of missing observations can be obtained as the difference between the total number of patients in each phase and the total number of observations
  2. COPD chronic obstructive pulmonary disease, SD standardized difference, IMV invasive mechanical ventilation
  3. For continuous variables, the standardized difference (d) is defined as follows:
  4. d = (\(\overline{\chi }\) survivor – \(\overline{\chi }\) non-survivor)/\(\sqrt{{(s}^{2}\mathrm{ survivor }+{s}^{2 }\mathrm{non}-\mathrm{survivor})/2}\)
  5. For dichotomous variables, the standardized difference is defined as follows:
  6. d = (\(\widehat{p}\) survivor –\(\widehat{p}\) non-survivor)/\(\sqrt{\left\{\widehat{p} \mathrm{survivor }\left(1-\widehat{p} \mathrm{non}-\mathrm{survivor} \right)+\widehat{p} \mathrm{survivor }\left(1-\widehat{p} \mathrm{non}-\mathrm{survivor}\right)\right\}/2}\)
  7. \(\overline{\chi }\): mean, s: standard deviation, \(\widehat{p}\): proportion
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