Table 4.
Variables included in the PAM-based clustering model.
| Cluster 1 | Cluster 2 | Cluster 3 | Cluster 4 | P -value | |
|---|---|---|---|---|---|
| (n = 144) | (n = 203) | (n = 158) | (n = 53) | ||
| Age | 51 (39, 63) abc | 69 (62, 76) | 67 (59, 74) | 68 (63, 72) | <0.001 |
| Gender | a | de | |||
| Female | 42 (29.2, −4.4) | 156 (76.8, 11.4) | 38 (24.1, −6.2) | 15 (23.8, −2.6) | <0.001 |
| Male | 102 (70.8, 4.4) | 47 (23.2, −11.4) | 120 (75.9, 6.2) | 38 (71.7, 2.6) | |
| No. of comorbidities | 0 (0,1) abc | 1 (0, 2) | 1 (0, 2) | 1 (1, 2) | <0.001 |
| Initial laboratory parameters | |||||
| White blood cells, ×109/L | 5.62 (4.47, 7.81) c | 5.97 (4.89, 7.60) e | 6.61 (4.72, 8.84) f | 11.38 (8.96, 15.77) | <0.001 |
| Neutrophils, ×109/L | 3.79 (2.62, 5.44) bc | 4.22 (3.03, 5.71) de | 5.46 (3.47, 7.74) f | 10.55 (7.64, 14.68) | <0.001 |
| Lymphocytes, ×109/L | 1.27 (0.90, 1.58) bc | 1.06 (0.77, 1.42) de | 0.61 (0.46, 0.82) | 0.51 (0.36, 0.76) | <0.001 |
| Platelets, ×109/L | 283 (223, 342) abc | 226 (177, 296) de | 161 (127, 222) | 157 (102, 216) | <0.001 |
| Total bilirubin, mmol/L | 8.9 (6.4, 12.1) bc | 8.3 (6.4, 12.1) de | 11.6 (8.3, 14.4) f | 14.6 (10.6, 23.4) | <0.001 |
| Lactate dehydrogenase, U/L | 258 (205, 320) bc | 284 (224, 344) de | 444 (333, 524) f | 601 (458, 795) | <0.001 |
| Urea, mmol/L | 3.95 (3.10, 5.28) bc | 4.60 (3.30, 5.70) de | 6.35 (4.70, 9.20) f | 9.80 (6.60, 13.85) | <0.001 |
| Creatinine, μmol/L | 70 (58, 82) bc | 63 (54, 78) de | 83 (66, 101) | 91 (75, 121) | <0.001 |
| hs-CRP, mg/L | 17.0 (6.7, 55.6) bc | 17.0 (5.9, 43.3) de | 109.8 (69.9, 162.3) | 112.3 (71.4, 186.3) | <0.001 |
| Prothrombin time, s | 13.7 (13.2, 14.2) bc | 13.8 (13.2, 14.3) de | 14.5 (13.8, 15.4) f | 16.2 (15.1, 17.6) | <0.001 |
| D-dimer, mg/mL | 0.91 (0.39, 2.10) bc | 1.17 (0.58, 2.59) de | 1.58 (0.86, 3.01) f | 21.00 (2.72, 21.00) | <0.001 |
| Hemoglobin, g/L | 131 (120, 141) a | 119 (109, 128) de | 131 (120, 141) | 132 (117, 142) | <0.001 |
| At admission | |||||
| Oxygen therapy | bc | de | f | ||
| Without oxygen inhalation | 32 (22.2, 1.6) | 47 (23.2, 2.4) | 20 (12.7, −2.0) | 1 (1.9, −3.2) | <0.001 |
| Nasal cannula | 105 (72.9, 1.7) | 147 (72.4, 2.0) | 103 (65.2, −0.6) | 20 (37.7, −4.8) | |
| Face mask with reservoir bag | 3 (2.1, −3.1) | 8 (3.9, −2.8) | 23 (14.6, 3.4) | 12 (22.6, 4.0) | |
| High-flow nasal cannula | 1 (0.7, 0) | 0 (0, −1.5) | 1 (0.6, −0.1) | 2 (3.8, 2.8) | |
| NIV | 2 (1.4, −1.6) | 0 (0, −3.4) | 6 (3.8, 0.2) | 12 (22.6, 7.8) | |
| IMV | 1 (0.7, −1.5) | 1 (0.5, −2.2) | 5 (3.2, 0.8) | 6 (11.3, 4.6) | |
| Vasopressor | 0 (0, −1.9) c | 0 (0, −2.4) e | 2 (1.3, −0.6) f | 8 (15.1, 7.7) | <0.001 |
| Disturbance of consciousness | 0 (0, −3.0) c | 2 (1.0, −2.9) e | 6 (3.8, −0.4) f | 16 (30.2, 9.8) | <0.001 |
| SpO2 | 97 (95, 98) bc | 97 (95, 99) de | 93 (86, 96) | 90 (79, 96) | <0.001 |
| Respiratory rate, /min | 20 (20, 22) bc | 20 (20, 22) de | 20 (20, 25) | 25 (20, 32) | <0.001 |
| Heart rate, /min | 92 (84, 105) a | 86 (77, 99) d | 96 (86, 109) | 88 (78, 113) | <0.001 |
| MAP, mmHg | 97 (90, 104) | 97 (89, 106) | 96 (89, 107) | 99 (91, 107) | 0.771 |
| During hospitalization | |||||
| Oxygen therapy | bc | de | f | ||
| Without oxygen inhalation | 4 (2.8, 2.3) | 2 (1.0, −0.2) | 0 (0, −1.5) | 0 (0, −0.8) | <0.001 |
| Nasal cannula | 121 (84.0, 7.1) | 173 (85.2, 9.6) | 34 (21.5, −11.2) | 0 (0, −9.1) | |
| Face mask with reservoir bag | 8 (5.6, −1.1) | 13 (6.4, −0.9) | 22 (13.9, −0.9) | 0 (0, −2.2) | |
| High-flow nasal cannula | 4 (2.8, −1.1) | 6 (3.0, −1.3) | 14 (8.9, 3.1) | 1 (1.9, −1.0) | |
| NIV | 3 (2.1, −4.8) | 1 (0.5, −7.0) | 57 (36.1, 9.3) | 18 (34.0, 4.3) | |
| IMV | 3 (2.1, −4.5) | 8 (3.9, −4.8) | 27 (17.1, 1.9) | 34 (64.2, 11.7) | |
| ECMO | 1 (0., −0.3) | 0 (0, −1.7) | 4 (2.5, 2.6) | 0 (0, −0.7) | |
| Vasopressor | 3 (2.1, −5.7) bc | 7 (3.4, −6.6) de | 43 (27.2, 3.8) f | 45 (84.9, 13.5) | <0.001 |
| Lowest SpO2 | 95 (93, 96) bc | 95 (92, 96) de | 89 (77, 94) f | 67 (56, 80) | <0.001 |
Quantitative variables are expressed as medians (interquartile ranges). Categorical variables are expressed as No. (%, adjusted standardized residuals). It is considered that the difference between the actual frequency and the expected frequency of this value is statistically significant if the absolute value of the adjusted standardized residual is >2. Bonferroni correction for multiple comparison was used in the comparison of cluster analysis results. The letters “a” to “f” indicate a significant difference between two group, respectively (a = cluster 1 vs. cluster 2, b = cluster 1 vs. cluster 3, c = cluster 1 vs. cluster 4, d = cluster 2 vs. cluster 3, e = cluster 2 vs. cluster 4, f = cluster 3 vs. cluster 4. PAM, partitioning around medoids; hs-CRP, high sensitivity C-reactive protein; NIV, noninvasive ventilation (bi-level); IMV, invasive mechanical ventilation; SpO2, peripheral blood oxygen saturation; MAP, mean arterial pressure; ECMO, extracorporeal membrane oxygenation.