Serial evaluation of the SOFA score to predict outcome in critically ill patients.

CONTEXT: Evaluation of trends in organ dysfunction in critically ill patients may help predict outcome.
OBJECTIVE: To determine the usefulness of repeated measurement the Sequential Organ Failure Assessment (SOFA) score for prediction of mortality in intensive care unit (ICU) patients.
DESIGN: Prospective, observational cohort study conducted from April 1 to July 31, 1999.
SETTING: A 31-bed medicosurgical ICU at a university hospital in Belgium. PATIENTS: Three hundred fifty-two consecutive patients (mean age, 59 years) admitted to the ICU for more than 24 hours for whom the SOFA score was calculated on admission and every 48 hours until discharge. MAIN OUTCOME MEASURES: Initial SOFA score (0-24), Delta-SOFA scores (differences between subsequent scores), and the highest and mean SOFA scores obtained during the ICU stay and their correlations with mortality.
RESULTS: The initial, highest, and mean SOFA scores correlated well with mortality. Initial and highest scores of more than 11 or mean scores of more than 5 corresponded to mortality of more than 80%. The predictive value of the mean score was independent of the length of ICU stay. In univariate analysis, mean and highest SOFA scores had the strongest correlation with mortality, followed by Delta-SOFA and initial SOFA scores. The area under the receiver operating characteristic curve was largest for highest scores (0.90; SE, 0.02; P<.001 vs initial score). When analyzing trends in the SOFA score during the first 96 hours, regardless of the initial score, the mortality rate was at least 50% when the score increased, 27% to 35% when it remained unchanged, and less than 27% when it decreased. Differences in mortality were better predicted in the first 48 hours than in the subsequent 48 hours. There was no significant difference in the length of stay among these groups. Except for initial scores of more than 11 (mortality rate >90%), a decreasing score during the first 48 hours was associated with a mortality rate of less than 6%, while an unchanged or increasing score was associated with a mortality rate of 37% when the initial score was 2 to 7 and 60% when the initial score was 8 to 11.
CONCLUSIONS: Sequential assessment of organ dysfunction during the first few days of ICU admission is a good indicator of prognosis. Both the mean and highest SOFA scores are particularly useful predictors of outcome. Independent of the initial score, an increase in SOFA score during the first 48 hours in the ICU predicts a mortality rate of at least 50%.