Table 1. Baseline characteristics of the ICU patients.
| Category | Variable | Number (Percent) or Median (Interquartile Range) | |
| BWH RoCI (n = 200) | ME ARDS (n = 243) | ||
| Demographic parameters | Age (years) | 60 (46–69) | 59 (45–71) |
| Gender (female) | 117 (59%) | 158 (65%) | |
| Race/ethnicity | |||
| White | 155 (78%) | 219 (90%) | |
| African-American | 26 (13%) | 5 (2%) | |
| Hispanic | 13 (7%) | 14 (6%) | |
| Asian or Pacific Islander | 6 (3%) | 5 (2%) | |
| Clinical parameters | ICU type | ||
| Medical | 200 (100%) | 126 (52%) | |
| Cardiac | 26 (11%) | ||
| Surgical | 82 (34%) | ||
| Trauma | 7 (3%) | ||
| Neurological | 2 (1%) | ||
| Cancer | |||
| Any | 89 (45%) | — | |
| Metastatic solid tumor | — | 4 (2%)a | |
| APACHE II score | 24 (18–30) | 22 (18–26) | |
| Acute kidney injury b | 57 (29%)a | — | |
| Need for mechanical ventilation | 90 (45%)a | — | |
| Heart failure c | 17 (9%)a | — | |
| Liver failure c | 20 (10%)a | 10 (4%)a | |
| Vasopressor use | 71 (36%)a | — | |
| Sepsis | 124 (62%) | 187 (77%) | |
| ARDS | 30 (15%) | 104 (43%)a | |
| Mortality data | 28-d mortality | 60 (30%) | 40 (16%) |
| In-hospital morality | 51 (26%) | — | |
| Overall mortality | 93 (47%) | — | |
| Peripheral blood biomarkers of ICU mortality | mtDNA (copies/µl) d | 3,379 (1,123–12,227) | 3,544 (1,130–10,557) |
| Procalcitonin (µg/l) | 3.6 (0.9–12.1)a | — | |
| Lactate (mg/dl) | 1.9 (1.2–4.0)a | — | |
a Data missing in BWH RoCI cohort for liver failure in one patient (0.5%), for acute kidney injury, need for mechanical ventilation, and heart failure in two patients (1%), for vasopressor use in four patients (2%), for procalcitonin measurement in 54 patients (27%), and for lactate measurement in 94 patients (47%). Data missing in the ME ARDS cohort for the presence of a solid tumor with metastasis and for liver failure in two patients (1%), and in all patients for particular variables, where indicated.
b Acute kidney injury defined by a ≥0.5 mg/dl increase in serum creatinine [17].
c Based on admitting physician report.
d mtDNA level represents NADH dehydrogenase 1 DNA level expressed as copies per microliter.