Acute respiratory distress syndrome (ARDS) is a major health problem, with the annual incidence in the United States approaching 200 000 cases.1 In the accompanying paper, Peter and colleagues present a systematic review and meta-analysis of nine randomised controlled trials (1073 patients) of corticosteroids for prevention and treatment of ARDS.2 ARDS is a form of severe respiratory failure resulting from direct pulmonary insults (for example, aspiration or pneumonia) or indirect systemic causes (for example, sepsis or trauma).3 This syndrome often has devastating consequences, such as the prolonged need for mechanical ventilation, a high probability of death, and long term physical and psychological sequelae in survivors. Treatment is unlikely to be successful in least developed countries because of limited critical care resources.4

No effective drug treatments are available for ARDS,5 but corticosteroids have attracted attention because they have anti-inflammatory properties that are relevant to ARDS pathology. They reduce both leakage of fluid through the alveolar-capillary membrane and the adhesion of neutrophils to the capillary endothelium, and they modulate the balance between proinflammatory and anti-inflammatory genes.6 However, these physiological benefits are tempered by concerns about side effects, including infections and neuromuscular weakness. …