Epidemiology

Overall, 10% to 15% of patients admitted to the intensive care unit meet the criteria for ARDS,[2][3] with an increased incidence among mechanically ventilated patients.[2]

The incidence of ARDS is estimated at 64 cases in 100,000 people, or 190,000 cases per year in the US. This incidence rate is 2 to 40 times greater than previous estimates, which probably does not represent a rising incidence but rather a historical underestimation.[4] The incidence of ARDS may be higher in the US than in Europe and other developed countries,[5] although evidence suggests that rates in the US may be declining.[6]

Critical illness, cigarette smoking, and alcohol use are predisposing factors for ARDS.[7][8] Sex, ethnicity, and race have not been associated with the incidence of ARDS.

The mortality of ARDS is approximately 30% to 50%,[3][4] although mortality in large clinical trials seems to be steadily decreasing.[9] The distinction between mild (PaO₂/FiO₂ 200-300), moderate (PaO₂/FiO₂ 100-200), and severe (PaO₂/FiO₂ ≤100) ARDS has been associated with clinical outcomes.[1] Ongoing research suggests there are at least two discrete ARDS subphenotypes, although the clinical implications of this are under investigation.[10][11][12]

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