Differences between Patients in Whom Physicians Agree and Disagree about the Diagnosis of ARDS.

RATIONALE: Because the Berlin ARDS definition has only moderate reliability, physicians disagree about the diagnosis of ARDS in some patients. Understanding the clinical differences between patients with agreement and disagreement in the diagnosis of ARDS may provide insight into the epidemiology and pathophysiology of this syndrome, and inform strategies to improve reliability of ARDS diagnosis.

OBJECTIVES: To characterize patients with diagnostic disagreement in ARDS among critical care trained physicians and compare them to patients with a consensus that ARDS developed.

METHODS: Patients with acute hypoxic respiratory failure (PaO2/FiO2 < 300 during invasive mechanical ventilation) were independently reviewed for ARDS by multiple critical care physicians and categorized as consensus-ARDS, disagreement in 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 - 47% across clinicians. Patients with disagreement had similar baseline comorbidity rates compared to patients with consensus-ARDS, but lower rates of ARDS risk factors and less severe measures of lung injury. Mean days of severe hypoxia (PaO2/FiO2 < 100) were 3.2 (95% 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 PaO2/FiO2 value could effectively discriminate patients (AUC = 0.90, 95% CI 0.88-0.92). For example, 63% of patients with pneumonia, shock and a PaO2/FiO2 < 110 had consensus-ARDS, while 100% of patients without pneumonia or shock and PaO2/FiO2 > 180 did not have ARDS.

CONCLUSIONS: Disagreement in 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 hypoxia severity can help guide clinicians in identifying patients with diagnosis of ARDS agreed upon by a consensus of physicians.