The use of maximum SOFA score to quantify organ dysfunction/failure in intensive care. Results of a prospective, multicentre study
Objective: To evaluate the performance of total maximum sequential organ failure assessment (SOFA) score and a derived measure, delta SOFA (total maximum SOFA score minus admission total SOFA) as a descriptor of multiple organ dysfunction/failure in intensive care. Design: Prospective, multicentre and multinational study. Setting: Forty intensive care units (ICUs) from Australia, Europe, North and South America. Patients: Data on 1,449 patients, evaluated at admission and then consecutively every 24 h until ICU discharge (11,417 records) during May 1995. Excluded from data collection were all patients with a length of stay in the ICU less than 2 days following uncomplicated scheduled surgery. Main outcome measure: Survival status at ICU discharge. Interventions: The collection of raw data necessary for the computation of a SOFA score on admission and then every 24 h, and basic demographic and clinical statistics. Measurements and main results: Mean total maximum SOFA score presented a very good correlation to ICU outcome, with mortality rates ranging from 3.2 % in patients without organ failure to 91.3 % in patients with failure of all the six organs analysed. A maximum score was reached 1.1 ± 0.2 days after admission for all the organ systems analysed. The total maximum SOFA score presented an area under the ROC curve of 0.847 (SE 0.012), which was significantly higher than any of its individual components. The cardiovascular score (odds ratio 1.68) was associated with the highest relative contribution to outcome. No independent contribution could be demonstrated for the hepatic score. No significant interactions were found. Principal components analysis demonstrated the existence of a two-factor structure that became clearer when analysis was limited to the presence or absence of organ failure (SOFA score ≥ 3 points) during the ICU stay. The first factor comprises respiratory, cardiovascular and neurological systems and the second coagulation, hepatic and renal systems. Delta SOFA also presented a good correlation to outcome. The area under the receiver operating characteristic (ROC) curve was 0.742 (SE 0.017) for delta SOFA, lower than the total maximum SOFA score or admission total SOFA score. The impact of delta SOFA on prognosis remained significant after correction for admission total SOFA. Conclusions: The results show that total maximum SOFA score and delta SOFA can be used to quantify the degree of dysfunction/failure already present on ICU admission, the degree of dysfunction/failure that appears during the ICU stay and the cumulative insult suffered by the patient. These properties make it a good instrument to be used in the evaluation of organ dysfunction/failure.
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