Table 3.
Clinical characteristics of early- versus late-onset acute respiratory distress syndrome in the derivation and validation cohorts
| Characteristic | Derivation Cohort |
Validation Cohort |
||||
|---|---|---|---|---|---|---|
| Early Onset (n = 108; 57%) | Late Onset (n = 81; 43%) | P Value | Early Onset (n = 115; 56%) | Late Onset (n = 90; 44%) | P Value | |
| Demographics | ||||||
| Age, yr | 38 (24-52) | 33 (23–47) | 0.728 | 48 (32–60) | 38 (25–56) | 0.015 |
| Sex, % male | 84/107 (79%) | 63/81 (78%) | 0.905 | 89/115 (77%) | 60/90 (67%) | 0.087 |
| Race | ||||||
| African American | 44/107 (41%) | 42/79 (53%) | 0.098 | 15/115 (13%) | 11/90 (12%) | 0.528 |
| White | 61/107 (57%) | 34/79 (43%) | 94/115 (82%) | 77/90 (86%) | ||
| Other race | 2/107 (2%) | 3/79 (4%) | 6/115 (5%) | 2/90 (2%) | ||
| Severity of illness | ||||||
| ISS | 25 (20–33) | 24 (19–29) | 0.248 | 34 (27–41) | 29 (21–38) | 0.063 |
| AIS thorax (0–5) | 3 (2–4) | 3 (0–3) | <0.001 | 4 (3–5) | 4 (3–4) | 0.001 |
| AIS head and neck (0–5) | 2 (0–3) | 2 (0–4) | 0.194 | 3 (2–4) | 3 (1–4) | 0.329 |
| AIS face (0–5) | 0 (0–2) | 0 (0–2) | 0.564 | 2 (1–2) | 2 (1–2) | 0.232 |
| AIS abdomen (0–5) | 2 (0–3) | 2 (0–3) | 0.990 | 2 (2–3) | 2 (1–4) | 0.724 |
| AIS extremities (0–5) | 2 (1–3) | 2 (0–3) | 0.134 | 2 (2–3) | 2 (1–3) | 0.381 |
| AIS external (0–5) | 1 (0–1) | 1 (0–1) | 0.157 | 2 (2–3) | 2 (1–3) | 0.381 |
| APACHE III w/o ABG | 61 (51–73) | 56 (45–70) | 0.109 | * | * | * |
| Etiology of injury | ||||||
| Blunt | 80/108 (74%) | 58/81 (72%) | 0.705 | 109/115 (95%) | 79/90 (88%) | 0.071 |
| Penetrating | 28/108 (26%) | 23/81 (28%) | 6/115 (5%) | 11/90 (12%) | ||
| Pulmonary contusion | 42/108 (39%) | 24/80 (30%) | 0.207 | 57/115 (50%) | 31/90 (34%) | 0.030 |
| Substance history | ||||||
| Alcohol use | 12/81 (15%) | 12/67 (18%) | 0.611 | 22/115 (19%) | 20/90 (22%) | 0.506 |
| Current smoker | 26/68 (38%) | 23/59 (39%) | 0.931 | 52/115 (45%) | 41/90 (46%) | 0.962 |
| Initial assessment | ||||||
| Lowest SBP | 80 (70–97) | 92 (80–105) | <0.001 | 85 (73–95) | 92 (82–100) | 0.006 |
| Temp max, °C | 36.3 (35.6–36.8) | 36.4 (35.9–36.8) | 0.684 | 38.1 (37.7–38.5) | 38.0 (37.6–38.6) | 0.498 |
| Hgb or Hct† | 12.3 ± 2.0 | 12.5 ± 2.3 | 0.392 | 30 (25–35) | 30 (26–34) | 0.792 |
| WBC‡ | 11.7 (8.4–18.6) | 12.5 (8.2–16.6) | 0.810 | 16.7 (12.5–21.7) | 17.4 (12.3–22.4) | 0.486 |
| Initial Cr | 1.1 (0.9–1.3) | 1.1 (0.9–1.3) | 0.810 | 1.2 (0.8–1.4) | 1.1 (0.9–1.3) | 0.205 |
| Interventions | ||||||
| Intravenous fluids, L | 5.4 (2.4–8.5) | 3.5 (2.0–7.0) | 0.077 | 8.0 (5.5–10.1) | 6.6 (4.6–9.7) | 0.087 |
| RBC, units | 4 (0–9) | 1 (0–6) | 0.009 | 2 (0–6) | 2 (0–5) | 0.548 |
| Plasma, units | 1 (0–4) | 0 (0–4) | 0.268 | 2 (0–4) | 2 (0–6) | 0.712 |
| Mortality | 23/108 (21%) | 22/81 (27%) | 0.349 | 13/115 (11%) | 13/90 (14%) | 0.503 |
Definition of abbreviations: ABG = arterial blood gas; AIS = Abbreviated Injury Scale; APACHE = Acute Physiology and Chronic Health Evaluation; Cr = creatinine; Hct = hematocrit; Hgb = hemoglobin; ISS = Injury Severity Score; RBC = red blood cells; SBP = systolic blood pressure; Temp max = maximal temperature; WBC = white blood cells; w/o = without.
Early-onset acute respiratory distress syndrome (ARDS) includes patients diagnosed within 48 hours of admission, whereas late-onset ARDS includes those diagnosed beyond 48 hours. Values represent median and interquartile range, mean ± standard deviation, or number and percentage. Distributions of continuous variables were compared using a Wilcoxon rank-sum test or Student t test as appropriate, and categorical variables were compared using a Pearson chi-square test.
APACHE III w/o ABG data were unavailable in the validation cohort.
Initial Hgb is provided for the derivation cohort and lowest Hct before enrollment is provided for the validation cohort.
WBC represents the initial white blood cell count in the derivation cohort and the highest before enrollment in the validation cohort.