Application of the sequential organ failure assessment score to cardiac surgical patients

Objective: To assess the applicability of the sequential organ failure assessment (SOFA) score to cardiac surgical patients. Design: Observational cohort study. Setting: Adult cardiac surgical ICU. Patients: Two hundred eighteen patients requiring ICU stay > 96 h. Measurements and results: The SOFA score was calculated daily until ICU discharge. Derived SOFA variables-total maximum SOFA (TMS), DeltaSOFA, maximum SOFA (maxSOFA), and Deltamax-SOFA-were considered. Length of ICU stay was 8.9 +/- 6.7 days (mean +/- SD). The mortality rate was 11.0%, in the ICU and 15.6% in the hospital. Nonsurvivors had higher TMS, DeltaSOFA, single-organ system, and mean total scores on day 1 (9.8 +/- 2.5 vs 7.8 +/- 2.3, p < 0.05) and thereafter until day 10. The total SOFA score on the first 10 days of ICU stay, time, survival status, and their interaction were all significant (p < 0.001), with higher SOFA scores for nonsurvivors, and lower scores for survivors that decreased as the number of days from operation increased. Cardiovascular score on day 1 carried the highest relative risk of mortality among other systems (risk ratio [RR]; 2.12; 95% confidence interval [CI], 1.31 to 3.45; p < 0.01), as did maximum cardiovascular score (RR, 2.81; 95% CI, 1.62 to 4.85; p < 0.001). A growing number of failing organs was associated with mortality, from the first to the sixth postoperative day (p < 0.05). Total score on day 1, TMS, DeltaSOFA, maxSOFA, and DeltamaXSOFA were reliable predictors of mortality with area under receiver operating characteristic curve of 0.71 (SE, 0.08), 0.89 (SE, 0.05), 0.86 (SE, 0.06), 0.88 (SE, 0.05), and 0.88 (SE, 0.06), respectively. Length of hospital stay was significantly associated (p = 0.05) to TMS and DeltaSOFA and not to other SOFA scores, age, or sex. Conclusions: The SOFA score may be used to grade the severity of postoperative morbidity in cardiac surgical patients without specific adaptations. The model identifies patients at increased risk for postoperative mortality.