Clinical Predictors of Hospital Mortality Differ Between Direct and Indirect ARDS.
Direct (pulmonary) and indirect (extrapulmonary) ARDS are distinct syndromes with important pathophysiologic differences. The goal of this study was to determine whether clinical characteristics and predictors of mortality differ between direct or indirect ARDS.



This retrospective observational cohort study included 417 patients with ARDS. Each patient was classified as having direct (pneumonia or aspiration, n = 250) or indirect (nonpulmonary sepsis or pancreatitis, n = 167) ARDS.



Patients with direct ARDS had higher lung injury scores (3.0 vs 2.8; P < .001), lower Simplified Acute Physiology Score II scores (51 vs 62; P < .001), lower Acute Physiology and Chronic Health Evaluation II scores (27 vs 30; P < .001), and fewer nonpulmonary organ failures (1 vs 2; P < .001) compared with patients with indirect ARDS. Hospital mortality was similar (28% vs 31%). In patients with direct ARDS, age (OR, 1.29 per 10 years; P = .01; test for interaction, P = .03), lung injury scores (OR, 2.29 per point; P = .001; test for interaction, P = .058), and number of nonpulmonary organ failures (OR, 1.67; P = .01) were independent risk factors for increased hospital mortality. Preexisting diabetes mellitus was an independent risk factor for reduced hospital mortality (OR, 0.47; P = .04; test for interaction, P = .02). In indirect ARDS, only the number of organ failures was an independent predictor of mortality (OR, 2.08; P < .001).



Despite lower severity of illness and fewer organ failures, patients with direct ARDS had mortality rates similar to patients with indirect ARDS. Factors previously associated with mortality during ARDS were only associated with mortality in direct ARDS. These findings suggest that direct and indirect ARDS have distinct features that may differentially affect risk prediction and clinical outcomes.
Department of Respiratory Medicine, Jinling Hospital, Nanjing University School of Medicine, Nanjing, People's Republic of China; Department of Critical Care Medicine, Wuxi No 2 People's Hospital, Wuxi, People's Republic of China.
Liang
L
Luo
Division of Allergy, Pulmonary, and Critical Care Medicine, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN. Electronic address: ciara.shaver@vanderbilt.edu.
Ciara M
CM
Shaver
Department of Biostatistics, Vanderbilt University Medical Center, Nashville, TN.
Zhiguo
Z
Zhao
Department of Biostatistics, Vanderbilt University Medical Center, Nashville, TN.
Tatsuki
T
Koyama
Departments of Medicine and Anesthesia, University of California San Francisco, San Francisco, CA.
Carolyn S
CS
Calfee
Division of Allergy, Pulmonary, and Critical Care Medicine, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN.
Julie A
JA
Bastarache
Division of Allergy, Pulmonary, and Critical Care Medicine, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN; Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN.
Lorraine B
LB
Ware
D000368:Aged; D015415:Biomarkers / Q000032:analysis; D015897:Comorbidity; D048909:Diabetes Complications / Q000401:mortality; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012128:Respiratory Distress Syndrome / Q000209:etiology / Q000401:mortality*; D012189:Retrospective Studies; D012307:Risk Factors; D012720:Severity of Illness Index
D015415:Biomarkers
ARDS; diabetes; direct lung injury; indirect lung injury; mortality
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