1. Among at-risk patients in the emergency department, administration of aspirin within 24 hours of presentation was not associated with a reduction in the incidence of acute respiratory distress syndrome (ARDS).
Evidence Rating Level: 2 (Good)
Study Rundown: ARDS, characterized by the rapid development of respiratory failure, is a common occurrence in the critical care setting and is associated with a high mortality rate. While the pathophysiology of this condition has been well established, there remains little known about how best to prevent it. Therefore, this study sought to determine whether early aspirin administration among at-risk patients could prevent the development of ARDS.
In a cohort of patients with known risk factors for ARDS, aspirin administration within 24 hours of presentation to the emergency department was not associated with a significant reduction in the incidence of ARDS after 7 days. Furthermore, the study found no significant differences in secondary outcomes or adverse events between aspirin administration and placebo. The results of this phase 2b trial therefore did not support continuation to a larger phase 3 trial.
This study was limited by a relatively low observed incidence of ARDS, which may affect its validity among more severely ill patients. Nevertheless, aspirin appears unlikely to reduce the incidence of ARDS in at-risk patients, and that further research is necessary to identify alternative therapies which can successfully prevent the development of ARDS.
Relevant Reading: Preventing ARDS: Progress, Promises, and Pitfalls
In-Depth [randomized controlled trial]: This double-blind placebo controlled randomized trial enrolled 400 patients at 16 US academic hospitals. These patients were all deemed at risk for ARDS, according to the Lung Injury Prediction Score. Patients who were already receiving antiplatelet therapy and patients who presented with ARDS at the time of screening were excluded from the trial. Patients underwent 1:1 randomization, receiving either placebo or treatment with aspirin in the form of a 325 mg loading dose followed by 81 mg/day within 24 hours of presentation to the ED, and continued until hospital day 7, discharge, or death. The primary outcome was ARDS development by study day 7, and the secondary outcomes included hospital and ICU length of stay, 28-day and 1-year survival, ventilator-free days, and ARDS-associated serum biomarker (i.e., Ang-2, IL-2, IL4, etc.) changes. Among the 390 patients eventually analyzed, administration of aspirin did not significantly reduce ARDS incidence by hospital day 7 as compared to patients treated with placebo (OR 1.24; 92.6%CI 0.67-2.31). In addition, there were no differences seen in either adverse events (i.e., bleeding related events, renal failure, change in GFR) or secondary outcomes.
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