Patient characteristics
| Variables | Overall N=693 | 4C Mortality Score | P value | ||
| Tertile 1 | Tertile 2 | Tertile 3 | |||
| (0–6) | (7–10) | (11–19) | |||
| n=217 | n=252 | n=224 | |||
| In-hospital mortality | 108 (15.6) | 1 (0.5) | 23 (9.1) | 84 (37.5) | <0.001 |
| Composite outcome | 211 (30.4) | 21 (9.7) | 68 (27.0) | 122 (54.5) | <0.001 |
| Age | 68.3±14.9 | 53.5±9.8 | 71.3±11.9 | 79.3±9.4 | <0.001 |
| Female | 244 (35.2) | 80 (36.9) | 96 (38.1) | 68 (30.4) | 0.17 |
| Japanese | 666 (96.1) | 202 (93.1) | 241 (95.6) | 223 (99.6) | 0.002 |
| Comorbidities | |||||
| Chronic cardiac disease* | 131 (18.9) | 9 (4.1) | 50 (19.8) | 72 (32.1) | <0.001 |
| Chronic renal disease | 52 (7.5) | 3 (1.4) | 9 (3.6) | 40 (17.9) | <0.001 |
| Malignancy | 15 (2.2) | 1 (0.5) | 3 (1.2) | 11 (4.9) | 0.002 |
| Moderate or severe liver disease | 1 (0.1) | 0 (0.0) | 0 (0.0) | 1 (0.4) | 0.35 |
| Obesity | 47 (6.8) | 22 (10.1) | 15 (6.0) | 10 (4.5) | 0.05 |
| Chronic pulmonary disease | 35 (5.1) | 1 (0.5) | 12 (4.8) | 22 (9.8) | <0.001 |
| Diabetes | 266 (38.4) | 62 (28.6) | 105 (41.7) | 99 (44.2) | 0.001 |
| Hypertension | 513 (74.0) | 154 (71.0) | 187 (74.2) | 172 (76.8) | 0.38 |
| Dyslipidaemia | 269 (38.8) | 104 (47.9) | 100 (39.7) | 65 (29.0) | <0.001 |
| Number of designated comorbidities† | <0.001 | ||||
| 0 | 271 (39.1) | 129 (59.4) | 97 (38.5) | 45 (20.1) | |
| 1 | 272 (39.2) | 75 (34.6) | 106 (42.1) | 91 (40.6) | |
| ≥2 | 150 (21.6) | 13 (6.0) | 49 (19.4) | 88 (39.3) | |
| Respiratory rate (breaths/min) | 20.55±5.93 | 18±5 | 20±6 | 23±6 | <0.001 |
| Peripheral oxygen saturation (%) | 96 (94, 98) | 97 (96, 98) | 96 (94, 98) | 95 (91, 97) | <0.001 |
| Systolic blood pressure (mm Hg) | 133±22 | 135±20 | 132±21 | 132±23 | 0.26 |
| Diastolic blood pressure (mm Hg) | 79±15 | 84±15 | 77±14 | 75±16 | <0.001 |
| Temperature (°C) | 38.0±0.9 | 38.0±0.9 | 37.9±0.9 | 38.1±0.8 | 0.15 |
| Heart rate (beats per minute) | 86±18 | 86±17 | 84±16 | 89±20 | 0.03 |
| Glasgow Coma Scale score | 15 (15, 15) | 15 (15, 15) | 15 (15, 15) | 15 (13, 15) | <0.001 |
| Haemoglobin (g/dL) | 13.4 (11.7, 14.7) | 14.4 (13.3, 15.4) | 13.15 (11.5, 14.5) | 12.5 (10.6, 14.0) | <0.001 |
| White cell count (×109/L) | 5.70 (4.40, 7.52) | 5.30 (4.10, 6.60) | 5.45 (4.40, 7.40) | 6.60 (4.70, 9.02) | <0.001 |
| Neutrophil count (×109/L) | 4.18 (2.93, 5.76) | 3.69 (2.64, 4.71) | 4.13 (2.98, 5.63) | 5.35 (3.52, 7.50) | <0.001 |
| Lymphocyte count (×109/L) | 0.92 (0.66, 1.24) | 1.12 (0.83, 1.52) | 0.93 (0.68, 1.23) | 0.78 (0.52, 1.02) | <0.001 |
| Platelet count (×109/L) | 19.0 (14.6, 24.8) | 20.0 (15.9, 25.6) | 19.1 (14.5, 25.5) | 17.1 (13.1, 22.9) | <0.001 |
| Sodium (mmol/L) | 138 (135, 141) | 139 (136, 141) | 137 (135, 140) | 137 (134, 141) | 0.004 |
| Potassium (mmol/L) | 4 (3.70, 4.30) | 4 (3.60, 4.22) | 4 (3.70, 4.20) | 4.10 (3.70, 4.50) | 0.04 |
| Bilirubin (mg/dL) | 0.65±0.47 | 0.65±0.59 | 0.64±0.35 | 0.66±0.45 | 0.85 |
| Lactate dehydrogenase (U/L) | 305±189 | 251±139 | 301±181 | 360±221 | <0.001 |
| Blood urea nitrogen (mmol/L) | 7.58±5.44 | 4.87±2.02 | 6.56±3.87 | 11.37±6.95 | <0.001 |
| Creatinine (µmol/L) | 72.49 (57.46, 93.70) | 67.18 (54.81, 77.79) | 71.60 (57.46, 88.40) | 86.63 (63.43, 135.25) | <0.001 |
| C reactive protein (mg/L) | 56.80 (19, 114.60) | 25.40 (7.10, 62.10) | 55.25 (19.73, 105.55) | 103.55 (50.70, 156.85) | <0.001 |
*Chronic cardiac disease was defined as heart failure, coronary artery disease, myocardial infarction and valvular heart disease.
†Number of designated comorbidities was defined using the Charlson Comorbidity Index, with the addition of clinician-defined obesity.
4C, Coronavirus Clinical Characterisation Consortium.