Table 1.
Baseline characteristics and clinical outcomes of patients enrolled in the Microbiome Cohort of the Acute Lung Injury Registry (MICALIR) study, categorized as patients with positive or negative respiratory cultures.
| Variable |
All |
Culture-positive |
Culture-negative^ |
P-value |
|---|---|---|---|---|
| N | 56 | 12 | 44 | |
| Age, mean (SD), years | 55.9 (15.3) | 54.7 (17.2) | 56.2 (14.9) | 0.88 |
| Males, N (%) | 34 (61) | 5 (42) | 29 (66) | 0.18 |
| BMI, mean (SD) | 32.2 (10.2) | 28.8 (7.1) | 33.1 (10.8) | 0.19 |
| History of diabetes, N (%) | 25 (45) | 6 (50) | 19 (43) | 0.75 |
| History of COPD, N (%) | 17 (30) | 5 (42) | 12 (27) | 0.47 |
| History of pulmonary fibrosis, N (%) | 4 (7) | 1 (9) | 3 (7) | 1.00 |
| History of smoking, N (%) | 1.00 | |||
| Current | 15 (27) | 3 (25) | 12 (27) | |
| Former | 15 (27) | 3 (25) | 12 (27) | |
| Never | 26 (46) | 6 (50) | 20 (46) | |
| Sepsis, N (%)# | 50 (89) | 12 (100) | 38 (86) | 0.32 |
| ARDS, N (%)$ | 21 (38) | 7 (58) | 14 (32) | 0.11 |
| High clinical index for pneumonia& | 34 (61) | 12 | 22 (50%) | 0.002 |
| Aspiration, N (%) | 14 (25) | 3 (25) | 11 (25) | 1 |
| SOFA score, median (IQR)∗ | 7.0 (4.8–9.0) | 8.5 (6.8–9.2) | 7.0 (4.0–9.0) | 0.09 |
| PaO2:FIO2 ratio, mean (SD), mmHg | 168.7 (81.6) | 172.2 (118.3) | 164.6 (67.2) | 0.51 |
| PEEP, median (IQR), cm | 5.0 (5.0–10.0) | 5.0 (5.0–9.0) | 5.0 (5.0–10.0) | 0.48 |
| Plateau pressure, mean (SD), cm | 23.3 (7.3) | 23.2 (8.8) | 23.6 (7.1) | 0.90 |
| Tidal volume (per kg of PBW), mean (SD), ml/kg | 6.7 (1.2) | 6.5 (1.5) | 6.7 (1.1) | 0.64 |
| SBP, mean (SD), mmHg | 118.7 (20.4) | 105.2 (14.8) | 122.3 (20.3) | 0.007 |
| Creatinine, median (IQR), mg/dl | 1.4 (0.8–2.4) | 1.9 (1.2–3.6) | 1.4 (0.8–2.4) | 0.26 |
| WBC, mean (SD), x 10-9 per liter | 13.9 (6.1) | 15.8 (6.5) | 13.4 (5.9) | 0.33 |
| Temperature, mean (SD), C | 37.1 (0.9) | 36.9 (0.9) | 37.1 (0.9) | 0.42 |
| Respiratory Virus infection, N (%) | 6 (11) | 2 (17)^^ | 4 (10) ## | 0.58 |
| ICU LOS, median (IQR), days | 8.0 (6.0–15.0) | 7.5 (6.0–18.2) | 8.5 (5.8–14.2) | 0.77 |
| VFD, median (IQR), days | 21 (0–24) | 10.5 (0–23.2) | 20.5 (9.5–24.2) | 0.29 |
| 30 Day mortality, N (%) | 13 (23) | 4 (33) | 9 (20) | 0.44 |
| Acute kidney injury, N (%) | 44 (79) | 11 (92) | 33 (75) | 0.42 |
Data are presented as mean (with standard deviations) or median (with interquartile range) for continuous variables (for normally and not normally distributed variables, respectively) and N (%) for categorical variables. Values of recorded variables were collected within 24 h of enrollment. P-values for comparisons between patients with positive respiratory cultures vs. negative respiratory cultures are shown, obtained from non-parametric Mann–Whitney test comparisons for continuous variables and Fisher tests for categorical variables. Statistically significant p-values (p < 0.05) are highlighted in bold. SD, standard deviation; IQR, interquartile range; BMI, body mass index; COPD, chronic obstructive pulmonary disease; ARDS, acute respiratory distress syndrome; SOFA, sequential organ failure assessment; PaO2, partial pressure of arterial oxygen; FiO2, Fractional inhaled concentration of oxygen; WBC, white blood cell count; PBW, predicted body weight; PEEP, positive end-expiratory pressure; SBP, systolic blood pressure; ICU LOS, intensive care unit length of stay; VFD, ventilator free days. ^ For 6 of the 44 culture-negative patients, there were no available respiratory sample clinical cultures within 48 h of research sample acquisition. These patients had negative routine clinical screening swabs for methicillin-resistant S. aureus and Vancomycin-resistant Enterococcus and were retrospectively deemed as low index of suspicion for pneumonia (e.g., intubated for airway protection for seizures or drug overdose). For these cases, we assigned the absence of a clinical respiratory microbiologic specimen as negative cultures. #Sepsis was defined according to the Sepsis-3 criteria. $ARDS was diagnosed according to the Berlin definition criteria. ∗SOFA score calculation does not include the neurologic component of SOFA score because all patients were intubated and receiving sedative medications, impairing our ability to perform assessment of the Glasgow Coma Scale in a consistent and reproducible fashion. ^^ N = 2, respiratory syncytial virus and influenza. ##N = 4, influenza, respiratory syncytial virus, metapneumovirus and parainfluenza.