Background Currently there is no ARDS definition or classification system that
allows optimal prediction of mortality in ARDS patients. This study aimed to
examine the predictive values of the AECC and Berlin definitions, as well as
clinical and respiratory parameters obtained at onset of ARDS and in the
course of the first seven consecutive days. Methods The observational study
was conducted at a 14-bed intensive care unit specialized on treatment of
ARDS. Predictive validity of the AECC and Berlin definitions as well as
PaO2/FiO2 and FiO2/PaO2*Pmean (oxygenation index) on mortality of ARDS
patients was assessed and statistically compared. Results Four hundred forty
two critically-ill patients admitted for ARDS were analysed. Multivariate Cox
regression indicated that the oxygenation index was the most accurate
parameter for mortality prediction. The third day after ARDS criteria were met
at our hospital was found to represent the best compromise between earliness
and accuracy of prognosis of mortality regarding the time of assessment. An
oxygenation index of 15 or greater was associated with higher mortality,
longer length of stay in ICU and hospital and longer duration of mechanical
ventilation. In addition, non-survivors had a significantly longer length of
stay and duration of mechanical ventilation in referring hospitals before
admitted to the national reference centre than survivors. Conclusions The
oxygenation index is suggested to be the most suitable parameter to predict
mortality in ARDS, preferably assessed on day 3 after admission to a
specialized centre. Patients might benefit when transferred to specialized ICU
centres as soon as possible for further treatment
