Table 1.
Characteristics of ARDS Phenotypes Stratified by Crs
| Baseline Variables | H Phenotype (Crs < 40) | Intermediate Phenotype (40 ≤ Crs < 50) | L Phenotype (Crs ≥ 50) | P Value |
|---|---|---|---|---|
| n (%) | 827 (74.04) | 154 (13.79) | 136 (12.18) | — |
| Clinician recognition of ARDS, n (%) | ||||
| At baseline | 198 (36.03) | 49 (31.82) | 32 (23.53)* | 0.0143 |
| During ICU stay | 574 (69.41) | 95 (61.69) | 78 (57.35)* | 0.0073 |
| Age, yr, mean ± SD | 59.97 ± 16.42 | 61.23 ± 15.95 | 60.15 ± 17.56 | 0.7542 |
| Males, n (%) | 472 (57.07) | 116 (75.32)* | 102 (75.00)* | <0.0001 |
| BMI, kg/m2, mean ± SD | 27.90 ± 7.64 | 28.24 ± 7.36 | 26.50 ± 5.30 | 0.1892 |
| Chronic diseases, n (%)† | ||||
| COPD | 178 (21.52) | 32 (20.78) | 29 (21.40) | 0.9786 |
| Diabetes mellitus | 209 (25.27) | 28 (18.18) | 18 (13.24)* | 0.0027 |
| Immune incompetence | 178 (21.52) | 23 (14.94) | 20 (14.71) | 0.0581 |
| Chronic cardiac failure | 77 (9.31) | 13 (8.44) | 10 (7.35) | 0.7384 |
| Chronic renal failure | 86 (10.40) | 12 (7.79) | 9 (6.62) | 0.2744 |
| Chronic liver failure | 35 (4.23) | 7 (4.55) | 9 (6.62) | 0.4664 |
| Number of chronic diseases, n (%) | ||||
| 0 | 327 (39.54) | 71 (46.10) | 71 (52.21)* | 0.0115 |
| 1 | 307 (37.12) | 58 (37.66) | 44 (32.35) | 0.5409 |
| ≥2 | 193 (23.34) | 25 (16.23) | 21 (15.44)* | 0.0279 |
| Type of risk factors for ARDS, n (%) | 0.4884 | |||
| None | 64 (7.74) | 11 (7.14) | 6 (4.41) | |
| Only nonpulmonary | 176 (21.28) | 32 (20.78) | 29 (21.32) | |
| Only pulmonary | 475 (57.44) | 84 (54.55) | 75 (55.15) | |
| Both | 112 (13.54) | 27 (17.53) | 26 (19.12) | |
| Risk factors for ARDS, n (%)† | ||||
| Pneumonia | 465 (56.23) | 82 (53.25) | 81 (59.56) | 0.5574 |
| Extrapulmonary sepsis | 137 (16.57) | 27 (17.53) | 23 (16.91) | 0.9559 |
| Blood transfusion | 135 (16.32) | 27 (17.53) | 20 (14.71) | 0.8085 |
| Trauma or pulmonary contusion | 36 (4.35) | 14 (9.09)* | 15 (11.03)* | 0.0015 |
| Other risk factors | 35 (4.23) | 8 (5.19) | 8 (5.88) | 0.6402 |
| Illness severity | ||||
| Gas exchange | ||||
| PaO2, mm Hg, mean ± SD | 93.30 ± 36.45 | 91.21 ± 33.26 | 99.29 ± 42.97 | 0.2308 |
| PaO2/FiO2, mm Hg, mean ± SD | 150.60 ± 66.44 | 156.53 ± 59.81 | 170.92 ± 69.00* | 0.0034 |
| PaO2/FiO2 < 150 mm Hg, n (%) | 451 (54.53) | 72 (46.75) | 58 (42.65) | 0.0136 |
| SpO2, %, median (IQR) | 96.0 (93.0–98.0) | 96.0 (93.0–98.0) | 97.0 (95.0–98.0) | 0.0547 |
| PaCO2, mm Hg, mean ± SD | 48.26 ± 16.04 | 46.85 ± 16.50 | 46.69 ± 14.38 | 0.2227 |
| pH, unit, mean ± SD | 7.30 ± 0.13 | 7.32 ± 0.11 | 7.33 ± 0.1* | 0.0303 |
| SOFA score, mean ± SD | ||||
| Adjusted for missing values | 10.63 ± 3.98 | 10.19 ± 3.56 | 9.98 ± 3.96 | 0.1483 |
| Nonpulmonary (adjusted for missing values) | 7.33 ± 3.92 | 6.97 ± 3.68 | 6.96 ± 3.94 | 0.4309 |
Definition of abbreviations: ARDS = acute respiratory distress syndrome; BMI = body mass index; COPD = chronic obstructive pulmonary disease; Crs = respiratory system compliance, ml/cm H2O; H phenotype = phenotype with high elastance or low Crs; IQR = interquartile range (first quartile to third quartile); L phenotype = phenotype with low elastance or high Crs; SOFA = Sequential Organ Failure Assessment; SpO2 = oxygen saturation as measured by pulse oximetry.
*
P value < 0.05, comparison versus H phenotype (Bonferroni correction).
†
Sum of percentages is >100% because patient could have more than one chronic disease and/or risk factor.