Table 2

Patients’ characteristics and outcomes depending on the severity of respiratory failure

VariablesSevere
(PaO2/FiO2 ≤100 mm Hg (n=63)
Moderate
(PaO2/FiO2 101–200 mm Hg (n=89)
Mild
(PaO2/FiO2 201–300 mm Hg (n=99)
Normal
(PaO2/FiO2 >300 mm Hg (n=155)
P value
Age at admission, years75 (64–81)72 (63–81)67 (57–76)58 (48–70)0.0001†
Males, n (%)51 (81.0)67 (75.3)65 (65.7)95 (61.3)0.02‡
Respiratory support at admission, n (%)
 Room air1 (1.6)5 (5.6)23 (23.2)93 (60.0)<0.0001§
 Nasal cannulae11 (17.5)14 (15.7)32 (32.3)35 (22.6)0.03¶
 Venturi mask6 (9.5)27 (30.3)23 (23.2)20 (12.9)0.001**
 Reservoir mask29 (46.0)31 (34.8)5 (5.1)3 (1.9)<0.0001††
 CPAP14 (22.2)9 (10.1)13 (13.1)4 (2.6)<0.0001‡‡
 NIV1 (1.6)2 (2.3)2 (2.0)0 (0.0)0.16
 IMV1 (1.6)1 (1.1)1 (1.0)0 (0.0)0.26
Blood count
 Haemoglobin, g/L13.4 (12.5–14.5)12.9 (11.8–14.6)13.4 (12.5–14.7)13.7 (12.7–14.8)0.05
 Platelets, per 109/μL206 (151–286)225 (160–292)205.5 (161–264)192 (152–247)0.12
 White blood cells, per 109/μL8.3 (6.2–12.2)8.1 (6.0–11.0)6.5 (5.1–9.0)5.9 (4.8–7.7)0.0001§§
 Neutrophils, per 109/μL6.9 (5.0–10.7)7.0 (4.5–10.0)4.9 (3.2–7.3)4.0 (3.0–5.6)0.0001¶¶
 Lymphocytes, per 109/μL0.74 (0.57–0.99)0.84 (0.62–1.14)1.07 (0.65–1.37)1.13 (0.84–1.50)0.0001***
 Blood urea nitrogen, mg/dL55 (39–74)49 (34–78)37 (29–52)29 (23–39)0.0001†††
 Creatinine, mg/dL0.91 (0.8–1.3)1.04 (0.76–1.39)0.92 (0.74–1.15)0.89 (0.72–1.05)0.007‡‡‡
 D-dimer, mg/L FEU1990 (701–6210)1355 (814–4025)971 (556–1830)579 (336–953)0.0001§§§
 Troponin T, ng/L20 (15–44)15.5 (9.0–31.5)14 (9–18)8 (6–12)0.0001¶¶¶
 C reactive protein, mg/L153 (86–219)119 (59–198)94.2 (40.5–148)44.2 (20–89.7)0.0001****
 Albumin, g/L24 (20–37)27 (22–59)27 (23–34)31 (27–34)0.004††††
 Interleukin-6, pg/mL167 (44–968)309 (42–1113)64 (27–496)47 (23–183)0.003‡‡‡‡
 Ferritin, μg/L1271 (499–2653)958 (423–2184)1513.5 (817–2824)775 (238–1484)0.06
Comorbidities
Cardiovascular diseases
 Cardiovascular disease*, n (%)38 (60.3)59 (66.3)56 (56.6)51 (32.9)<0.0001§§§§
 Hypertension, n (%)30 (47.6)42 (47.2)47 (47.5)39 (25.2)<0.0001¶¶¶¶
 Ischaemic heart disease, n (%)8 (12.7)14 (15.7)11 (11.1)8 (5.2)0.05
 Arrythmia, n (%)8 (12.7)16 (18.0)9 (9.1)14 (9.0)0.16
 Vasculopathy, n (%)8 (12.7)8 (9.0)9 (9.1)7 (4.5)0.19
 Valvulopathy, n (%)2 (3.2)5 (5.6)3 (3.0)4 (2.6)0.67
 Heart failure, n (%)3 (4.8)7 (7.9)4 (4.0)2 (1.3)0.07
Other
 Diabetes mellitus, n (%)9 (14.3)21 (23.6)20 (20.0)18 (11.6)0.07
 Endocrinology disease, n (%)7 (11.1)17 (19.1)13 (13.1)18 (11.7)0.37
 Neurological disease, n (%)8 (12.7)16 (18.0)13 (13.1)12 (7.7)0.12
 Immune depression, n (%)3 (4.8)12 (13.5)11 (11.1)12 (7.7)0.24
 Hypothyroidism, n (%)2 (3.2)9 (10.1)9 (9.1)10 (6.5)0.35
 Kidney disease, n (%)5 (7.9)8 (9.0)7 (7.1)8 (5.2)0.70
 Orthopaedic disease, n (%)3 (4.8)7 (7.9)8 (8.1)13 (8.4)0.86
 Gastrointestinal disease, n (%)6 (9.5)8 (9.0)4 (4.0)10 (6.5)0.42
 Severe obesity, n (%)6 (9.5)12 (13.5)1 (1.0)7 (4.5)0.002*****
 COPD, n (%)7 (11.1)9 (10.1)4 (4.0)5 (3.2)0.04†††††
 CKD, n (%)3 (4.8)9 (10.1)5 (5.1)6 (3.9)0.26
 BPH, n (%)7 (11.1)9 (10.1)4 (4.0)5 (3.2)0.04‡‡‡‡‡
 Active solid cancer, n (%)2 (3.2)7 (7.9)4 (4.0)7 (4.5)0.59
 Previous cancer, n (%)4 (6.4)4 (4.5)2 (2.0)8 (5.2)0.52
 Stroke, n (%)3 (4.8)6 (6.7)4 (4.0)4 (2.6)0.44
 Other neurological disease, n (%)4 (6.4)5 (5.6)4 (4.0)1 (0.7)0.03§§§§§
 Asthma, n (%)1 (1.6)3 (3.4)4 (4.0)5 (3.2)0.90
Chronic treatments
 ACEi at admission, n (%)12 (19.1)13 (14.6)24 (24.2)9 (5.8)<0.0001¶¶¶¶¶
ACEi name, n (%)
 Ramipril6 (50.0)9 (64.3)13 (54.2)5 (55.6)0.90
 Enalapril2 (16.7)3 (21.4)8 (33.3)3 (33.3)0.71
 Lisinopril1 (8.3)1 (7.1)1 (4.2)0 (0.0)
 Perindopril1 (8.3)1 (7.1)0 (0.0)1 (11.1)
 Zofenpril1 (8.3)0 (0.0)1 (4.2)0 (0.0)
 Captopril1 (8.3)0 (0.0)0 (0.0)0 (0.0)
 Zanipril0 (0.0)0 (0.0)1 (4.2)0 (0.0)
 ARBs, n (%)9 (14.3)16 (18.0)10 (10.1)26 (16.8)0.41
ARB name, n (%)
 Olmesartan6 (66.7)6 (35.3)2 (20.0)11 (40.7)0.23
 Telmisartan1 (11.1)3 (17.7)3 (30.0)4 (14.8)0.71
 Valsartan1 (11.1)4 (23.5)1 (10.0)5 (18.5)0.84
 Irbesartan0 (0.0)3 (17.7)3 (30.0)4 (14.8)
 Losartan1 (1.1)1 (5.9)1 (10.0)3 (11.1)
 ACEi or ARBs, n (%)21 (33.3)29 (32.6)34 (34.3)34 (21.9)0.10
In-hospital treatments
 Lopinavir/Ritonavir, n (%)40 (63.5)50 (56.2)64 (64.6)87 (56.1)0.45
 Hydroxychloroquine, n (%)51 (81.0)74 (83.2)89 (89.9)120 (77.4)0.09
 Corticosteroids, n (%)26 (41.3)37 (41.6)24 (24.2)18 (11.6)<0.0001******
 Tocilizumab, n (%)17 (27.0)21 (23.6)27 (27.3)22 (14.2)0.03††††††
 LMWH, n (%)48 (76.2)66 (74.2)62 (62.6)73 (47.1)<0.0001‡‡‡‡‡‡
 Experimental drugs, n (%)1 (1.6)0 (0.0)0 (0.0)2 (1.3)0.74
Outcomes
 CPAP during hospitalisation, n (%)45 (71.4)50 (56.2)49 (49.5)32 (20.7)<0.0001§§§§§§
 Median (IQR) CPAP max PEEP12 (10–14)10 (10.0–12.3)10 (10.0–12.5)10 (10.0–12.5)0.02¶¶¶¶¶¶
 Intubation, n (%)11 (17.5)5 (5.6)9 (9.1)11 (7.1)0.06
 In-hospital mortality, n (%)35 (55.6)43 (48.3)16 (16.2)10 (6.5)<0.0001*******
 Days from admission to death15 (6–37)25 (7–34)35 (24–41)36 (30–41)0.0001†††††††
  • Data are expressed as frequencies or medians (IQR). Comorbidities with ≥3% prevalence were reported. A complete list of comorbidities is reported in table 1 of the online supplemental file.

  • *At least one of the following: hypertension, arrhythmia, ischaemic heart disease, vasculopathy, heart failure, valvulopathy.

  • †Severe vs Mild p=0.02; Severe vs Normal p<0.0001; Moderate vs Normal p<0.0001; Mild vs Normal p<0.0001.

  • ‡Severe vs Mild p=0.04; Severe vs Normal p=0.005; Moderate vs Normal p=0.03.

  • §Severe vs Mild p=0.0002; Severe vs Normal p<0.0001; Moderate vs Mild p=0.0007; Moderate vs Normal p<0.0001; Mild vs Normal p<0.0001.

  • ¶Severe vs Mild p=0.04; Moderate vs Mild p=0.008.

  • **Severe vs Moderate p=0.002; Severe vs Mild p=0.03; Moderate vs Normal p=0.0009; Mild vs Normal p=0.03.

  • ††Severe vs Mild p<0.0001; Severe vs Normal p<0.0001; Moderate vs Mild p<0.0001; Moderate vs Normal p<0.0001.

  • ‡‡Severe vs Moderate p=0.04; Severe vs Normal p<0.0001; Moderate vs Normal p=0.01; Mild vs Normal p=0.001.

  • §§Severe vs Mild p=0.03; Severe vs Normal p<0.0001; Moderate vs Normal p<0.0001.

  • ¶¶Severe vs Mild p=0.008; Severe vs Normal p<0.0001; Moderate vs: Mild p=0.01; Moderate vs Normal p<0.0001; Mild vs Normal p=0.02.

  • ***Severe vs Mild p=0.01; Severe vs Normal p<0.0001; Moderate vs Normal p=0.0006.

  • †††Severe vs Mild p=0.002; Severe vs Normal p-value<0.0001; Moderate vs: Mild p=0.02; Moderate vs Normal p<0.0001; Mild vs Normal p=0.0006.

  • ‡‡‡Moderate vs Normal p=0.004.

  • §§§Severe vs Mild p=0.02; Severe vs Normal p<0.0001; Moderate vs: Mild p=0.02; Moderate vs Normal p<0.0001; Mild vs Normal p=0.003.

  • ¶¶¶Severe vs Normal p<0.0001; Moderate vs: Normal p=0.001; Mild vs Normal p=0.01.

  • ****Severe vs Mild p=0.003; Severe vs Normal p<0.0001; Moderate vs Normal p<0.0001; Mild vs Normal p=0.0002.

  • ††††Severe vs Normal p=0.002.

  • ‡‡‡‡Severe vs Normal p=0.02; Moderate vs: Normal p=0.004.

  • §§§§Severe vs Normal p=0.0002; Moderate vs Normal p<0.0001; Mild vs Normal p=0.0002.

  • ¶¶¶¶Severe vs Normal p=0.001; Moderate vs Normal p=0.0004; Mild vs Normal p=0.0003.

  • *****Severe vs Moderate p=0.009; Moderate vs Mild p=0.0007; Moderate vs Normal p=0.01; Mild vs Normal p=0.01.

  • †††††Severe vs Normal p=0.02; Moderate vs Normal p=0.03.

  • ‡‡‡‡‡Severe vs Normal p=0.02; Moderate vs Normal p=0.03.

  • §§§§§NA.

  • ¶¶¶¶¶Severe vs Normal p=0.003; Moderate vs Normal p=0.02; Mild vs Normal p<0.0001.

  • ******Severe vs Mild p=0.02; Severe vs Normal p<0.0001; Moderate vs Mild p=0.01; Mild vs Normal p=0.008.

  • ††††††Severe vs Normal p=0.03; Mild vs Normal p=0.01.

  • ‡‡‡‡‡‡Severe vs Normal p<0.0001; Moderate vs Mild p=0.02; Moderate vs Normal p<0.0001; Mild vs Normal p<0.0001.

  • §§§§§§Severe vs Mild p=0.006; Severe vs Normal p<0.0001; Moderate vs Normal p<0.0001; Mild vs Normal p<0.0001.

  • ¶¶¶¶¶¶Severe vs Moderate p=0.005.

  • *******Severe vs Mild p<0.0001; Severe vs Normal p<0.0001; Moderate vs Mild p<0.0001; Moderate vs Normal p<0.0001; Mild vs Normal p=0.01.

  • †††††††Severe vs Mild p<0.0001; Severe vs Normal p<0.0001; Moderate vs Normal p<0.0001.

  • ACEi, ACE inhibitor; ARB, angiotensin receptor blocker; BPH, benign prostate hypertrophy; CKD, chronic kidney disease; COPD, chronic obstructive pulmonary disease; CPAP, continuous positive airway pressure ; FEU, fibrinogen-equivalent units; IMV, invasive mechanical ventilation; LMWH, low molecular weight heparin ; NIV, non-invasive ventilation; PEEP, positive end expiratory pressure; P/F, partial pressure of oxygen to fraction of inspired oxygen ratio (PaO2/FiO2).