Aspirin as a Treatment for Acute Respiratory Distress Syndrome: a randomised placebo controlled clinical trial

There is no pharmacological treatment for the acute respiratory distress syndrome (ARDS). Platelets play an important role in the pathophysiology of ARDS. Pre-clinical, observational and clinically relevant models of ARDS indicate aspirin as a potential therapeutic option. Is enteral aspirin 75mg once daily safe and effective in improving surrogate outcomes in adult patients with ARDS? This randomised, double blind (patient and investigator), allocation concealed, placebo-controlled phase 2 trial was conducted in five UK intensive care units. Patients fulfilling the Berlin definition of ARDS were randomly assigned in a 1:1 ratio to receive enteral aspirin 75mg or placebo, for a maximum of 14 days, using a computer-generated randomisation schedule, with variable block size, stratified by vasopressor requirement. The primary endpoint was oxygenation index (OI) at day 7. Secondary outcomes included safety parameters and other respiratory physiological markers. Analyses were by intention to treat. The trial was stopped early, due to slow recruitment, after 49 of a planned 60 patients were recruited. 24 patients were allocated to aspirin and 25 to placebo. There was no significant difference in day 7 OI (unadjusted mean 54.4 [SD 26.8] in aspirin group, 42.4 [SD 25] in placebo group; mean difference 12.0, 95% CI -6.1 to 30.1, p= 0.19). Aspirin did not significantly impact the secondary outcomes. There was no difference in the number of adverse events between the groups (13 in each, odds ratio 1.04, 95% CI 0.56 to 1.94, p=0.56). Aspirin was well tolerated but did not improve OI or other physiological outcomes, a larger trial is not feasible in its current design.