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Table 2 Characteristics of 2017 critically ill patients included in machine learning analysis according to overall or cluster (phenotype) population

From: Deploying unsupervised clustering analysis to derive clinical phenotypes and risk factors associated with mortality risk in 2022 critically ill patients with COVID-19 in Spain

Variablea

Overall

n = 2017

Cluster C (severe)

n = 857

Cluster B (moderate)

n = 623

Cluster A (mild)

n = 537

General characteristics and severity of illness

Age, mean (IQR), years

64 (55–71)

66 (58–72)

63 (53.5–71.5)

63 (53–70)***

Male, n (%)

1419 (70.3)

626 (73.0)

416 (66.8)

377 (70.2)*

APACHE II, mean (IQR)b

13 (10–17)

17 (14–22)

13 (10–16)

12 (9–16)***

SOFA, mean (IQR)c

5 (3.7)

7 (6–8)

5 (3–7)

4 (3–5)***

Laboratory findings

D-Lactate dehydrogenase, mean (IQR), U/L

537 (417–707)

670 (554–929)

477 (378–570)

474 (372–564)***

White blood cell, mean (IQR), × 109

8.8 (6.2–12.2)

10 (6.9–13.6)

8.5 (6–11.7)

7.7 (5.8–10.2)***

Serum Creatinine, mean (IQR), mg/dL

0.88 (0.7–1.1)

0.99 (0.76–1.36)

0.80 (0.66–1.00)

0.80 (0.66–1.01)***

C-Reactive Protein, mean (IQR), mg/mL

15.5 (9.1–24.3)

18 (10–26)

14 (9–22)

14 (8–2)***

Procalcitonin, mean (IQR), ng/mL

0.3 (0.1–2.0)

0.5 (0.2–1.3)

0.2 (0.1–0.5)

0.2 (0.1–0.6)***

Serum lactate, mean (IQR), mmol/L

1.5 (1.1–2.0)

1.6 (1.2–2.2)

1.4 (1.0–1.9)

1.5 (1.1–1.9)***

D dimer, mean (IQR), ng/mL

1593 (720–3790)

2260 (1009–4894)

1319 (634–3548)

1090 (580–2100)***

Ferritin, mean (IQR), ng/mL

1600 (1290–2240)

1800 (1416–2377)

1554 (1271–1936)

1538 (1280–1899)***

Treatments

Corticosteroids, n (%)

1171 (58.0)

535 (62.4)

338 (54.3)

298 (55.5)**

Antibiotics, n (%)

1814 (89.9)

780 (91.0)

573 (92.0)

461 (85.8)***

Lopinavir/ritonavir, n (%)

1696 (84.0)

698 (81.4)

508 (81.5)

452 (84.2)

Hydroxychloroquine, n (%)

1861 (92.3)

805 (93.9)

566 (90.0)

490 (91.2)

Tocilizumab, n (%)

573 (28.4)

234 (27.3)

211 (33.9)

128 (23.8)***

Interferon β, n (%)

713 (35.3)

301 (35.1)

224 (36.0)

188 (35.0)

Coexisting condition and Comorbidities

Arterial hypertension, n (%)

932 (46.2)

548 (63.9)

173 (27.8)

211 (39.3)***

Obesity (BMI > 30), n (%) d

653 (32.3)

294 (34.3)

200 (32.1)

159 (29.6)

Diabetes, n (%)

418 (20.7)

198 (23.1)

108 (17.3)

112 (20.9)*

Coronary arterial disease, n (%)

124 (6.1)

48 (5.6)

41 (6.6)

35 (6.5)

COPD, n (%)

148 (7.3)

73 (8.5)

38 (6.1)

37 (6.9)

Chronic renal disease, n (%) e

85 (4.2)

44 (5.1)

10 (1.6)

31 (5.8)***

Hematologic disease, n (%)

72 (3.5)

30 (3.5)

22 (3.5)

20 (3.7)

Asthma, n (%)

120 (5.9)

34 (4.0)

45 (7.2)

41 (7.6)**

HIV, n (%)

5 (0.2)

2 (0.2)

1 (0.2)

2 (0.4)

Pregnancy, n (%)

4 (0.19)

0 (0.0)

3 (0.5)

1 (0.2)

Autoimmune disease, n (%) f

74 (3.6)

36 (4.2)

18 (2.9)

20 (3.7)

Chronic heart disease, n (%) g

57 (2.8)

26 (3.0)

10 (1.6)

21 (3.9)

Neuromuscular disease, n (%)

16 (0.8)

8 (0.9)

5 (0.8)

3 (0.6)

Oxygenation and ventilator support

Oxygen mask, n (%)

325 (16.1)

96 (11.2)

105 (16.9)

124 (23.1)***

High Flow nasal cannula, n (%)

375 (18.6)

27 (3.2)

3 (0.5)

345 (64.2)***

Non-invasive ventilation, n (%)

140 (6.9)

50 (5.8)

26 (4.2)

64 (11.9)***

Invasive mechanical ventilation, n (%)

1172 (58.1)

694 (81.0)

475 (76.2)

3 (0.6)***

PaO2/FiO2, mean (IQR)

132 (96–163)

126 (88–155)

165 (144–212)

111 (82–133)***

Complications

Shock, n (%) h

904 (44.8)

652 (76.1)

196 (31.5)

56 (10.4)

Acute kidney dysfunction, n (%) i

579 (28.7)

350 (40.8)

118 (18.9)

111 (20.7)***

Myocardial dysfunction, n (%) j

169 (8.3)

96 (11.2)

43 (6.9)

30 (5.6)***

 > 2 Quadrant infiltrates in chest x-ray, n (%)

1327 (65.7)

573 (66.8)

413 (66.3)

341 (63.5)

ICU crude mortality, n (%)

657 (32.6)

389 (45.4)

159 (25.5)

109 (20.3)***

  1. IQR interquartile range, APACHE II Acute Physiology and Chronic Health Evaluation II, SOFA Sequential Organ Failure Assessment, BMI body mass index, COPD Chronic obstructive pulmonary disease, HIV human immunodeficiency viruses, PaO2/FiO2 Partial pressure arterial oxygen/ fraction of inspired oxygen
  2. aCorresponds to minimum or maximum value, as appropriate, within 12 h of ICU admission. The variables in this Table were no transformed for your comparison
  3. bAPACHE II score to the severity of illness, the score is obtained by adding the following components (1) 12 clinical and laboratory variables each with a score range of 0 to 4 points (APS). The APS is determined from the worst physiologic values during the initial 24 h after ICU admission, (2) age with a range 0 to 6 points and (3) Chronic health points if the patients has history of severe organ system insufficiency or is immunocompromised assign 5 points if the patients is no operative or emergency postoperative and 2 points for elective postoperative patients with a total score range of 0 to 71
  4. cSOFA score corresponds to the severity of organ dysfunction, reflecting six organ systems each with a score range of 0 to 4 points (cardiovascular, hepatic, hematologic, respiratory, neurological, renal), with a total score range of 0 to 24
  5. dDefined as a body mass index (calculated as weight in kilograms divided by height in meters squared) of 30 or greater
  6. eBaseline eGFR < 60 on at least two consecutive values at least 12 weeks apart prior or hemodialysis
  7. fIncluded acute leukemia, myelodysplastic syndrome and Lymphomas
  8. gAccording to the New York Heart Association (NYHA) Functional Classification III and IV
  9. hDefined as patients in whom adequate fluid resuscitation therapy are unable to restore hemodynamic stability and need any dose of vasopressor drugs
  10. iDefine as an abrupt and sustained (more than 24 h) decrease in kidney function and categorized according to RIFLE criteria
  11. jDefine as an acute decrease in ejection fraction (EF) with dilatation of ventricles observed in echocardiography upon ICU admission
  12. All comparison between clusters. *p < .05; **p < .01; ***p < .001, others comparison p > .01
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