The addition of lactate to SOFA score improves the prediction of mortality in patients with severe burns–A retrospective cohort study

• We investigated the prognostic value of two composite indexes for burn patients. • Adding lactate to SOFA at an early stage seems to be a useful prognostic tool. • The addition of the CCI to rBAUX + SAPS 3 adds little to the prognostic value. • The combined score of lactate and SOFA is interesting for future studies. Major burn injury is a serious condition associated with high morbidity and mortality. In addition to Baux and revised Baux scores, several scores for prediction of outcome have been employed during the years, including SOFA (Sequential Organ Failure Assessment) score and lactate on admission. The goal of the present study was to investigate two early composite indexes, with the hypothesis that they would more accurately predict mortality. SOFALx was formulated by adding the highest blood lactate of day 1, 2 and 3 after admission to the SOFA score of the corresponding day. CCIrBS was defined as the sum of Charlson Comorbidity Index with revised Baux Score and SAPS-3 (Simplified Acute Physiology Score). We investigated the prognostic value of these composite indexes in patients admitted to the burn center at Uppsala University Hospital with major burn injury (≥ 20 % TBSA) between January 2017 and December 2022. Primary outcome was 180-day mortality. Among the 95 patients that were included, 38 were non-survivors and 57 were survivors. Both composite indexes had a proper prognostic value. The prognostic accuracy was best for SOFALx on day 2 (SOFAL2) with median value (IQR) of 8.3 (4.8) for survivors vs. 16.5 (7.9) for non-survivors (p < 0.001) and the area under the ROC curve of 0.923. CCIrBS gave an area under the ROC curve of 0.916. The value of this composite index was 138 (63) in survivors vs. 212 (52) in non-survivors (p < 0.001). Both SOFALx and CCIrBS are accurate prognostic indexes. Since SOFALx, in comparison to the more complex CCIrBS, is easy to use, this composite index is interesting for future studies.