Abstract
RATIONALE: Because the Berlin definition of acute respiratory distress syndrome (ARDS) has only moderate reliability, physicians disagree about the diagnosis of ARDS in some patients. Understanding the clinical differences between patients with agreement and disagreement about the diagnosis of ARDS may provide insight into the epidemiology and pathophysiology of this syndrome, and inform strategies to improve the reliability of ARDS diagnosis. OBJECTIVES: To characterize patients with diagnostic disagreement about ARDS among critical-care-trained physicians and compare them with patients with a consensus that ARDS developed. METHODS: Patients with acute hypoxemic respiratory failure (arterial oxygen tension/pressure [Pa(O(2))]/fraction of inspired oxygen [Fi(O(2))] < 300 during invasive mechanical ventilation) were independently reviewed for ARDS by multiple critical-care physicians and categorized as consensus-ARDS, disagreement about the diagnosis, or no ARDS. RESULTS: Among 738 patients reviewed, 110 (15%) had consensus-ARDS, 100 (14%) had disagreement, and 528 (72%) did not have ARDS. ARDS diagnosis rates ranged from 9% to 47% across clinicians. Patients with disagreement had baseline comorbidity rates similar to those of patients with consensus-ARDS, but lower rates of ARDS risk factors and less severe measures of lung injury. Mean days of severe hypoxemia (Pa(O(2))/Fi(O(2)) < 100) were 3.2 (95% confidence interval [CI], 2.6-3.9), 2.0 (95% CI, 1.5-2.4), and 0.8 (95% CI, 0.7-0.9) among patients with consensus-ARDS, disagreement, and no ARDS, respectively. Hospital mortality was 37% (95% CI, 28-46%), 35% (95% CI, 26-44%), and 19% (95% CI, 15-22%) across groups. Simple combinations of specific ARDS risk factors and lowest Pa(O(2))/Fi(O(2)) value could effectively discriminate patients (area under the receiver operating characteristic curve = 0.90; 95% CI, 0.88-0.92). For example, 63% of patients with pneumonia, shock, and Pa(O(2))/Fi(O(2)) < 110 had consensus-ARDS, whereas 100% of patients without pneumonia or shock and Pa(O(2))/Fi(O(2)) > 180 did not have ARDS. CONCLUSIONS: Disagreement about the diagnosis of ARDS is common and can be partly explained by the difficulty of dichotomizing patients along a continuous spectrum of ARDS manifestations. Considering both the presence of key ARDS risk factors and hypoxemia severity can help guide clinicians in identifying patients with diagnosis of ARDS agreed upon by a consensus of physicians.