ARDS mortality is unchanged since 1994

January 23, 2009

Mortality in patients with acute respiratory distress syndrome (ARDS) has not fallen since 1994, according to a comprehensive review of major studies that assessed ARDS deaths. This disappointing finding contradicts the common wisdom that ARDS mortality has been in steady decline.

The study was published in the first issue for February of the American Journal of Respiratory and Critical Care Medicine.

The authors reviewed all prospective observational and randomized controlled trials between 1984 and 2006 that included more than 50 ARDS/ALI patients and reported mortality.

Contrary to the suggested benchmark mortality of all ARDS and related acute lung injury (ALI) cases being 25-30 percent, the authors state that their findings suggest a benchmark mortality of 40- 45 percent.

"Our systematic review has shown that mortality due to ARDS has remained relatively unchanged since 1994, coincident with the publication of the current syndrome definition," wrote Dr. Niall Ferguson, director of clinical research, critical care medicine, of the University Health Network of the University of Toronto. "Our results highlight the need for future effective therapeutic interventions for this highly lethal syndrome.'"

"The main finding of our systematic review is that mortality due to ARDS has remained static at 44 percent for observational studies and 36 percent for randomized controlled trials since a standard definition [of ARDS] was introduced in 1994," wrote Dr. Ferguson.

The findings are attributed to several possibilities, all or some of which may explain the steady mortality of ARDS:

• There are an inadequate number effective therapies for ARDS;
• The effective therapies that do exist (low tidal volume) are not consistently implemented in all treatment facilities; Furthermore, adherence to supportive measures that could improve outcomes may also be variable;
• ARDS itself, defined as a broad syndrome, defies effective therapies and treatments tailored to subgroups of patients should be considered and tested; and
• The decrease in ARDS mortality between 1984 and 1994 may have been because of a lack of consistent definition, but the study did not specifically confirm this.

"Most importantly," concluded Dr. Ferguson, "our results highlight the need for future effective therapeutic interventions for this highly lethal syndrome."

Source: American Thoracic Society