Predicting Burn Mortality Using a Simple Novel Prediction Model

Abstract

Background Prediction of outcome for burn patients allows appropriate allocation of resources and prognostication. There is a paucity of simple to use burn-specific mortality prediction models which consider both endogenous and exogenous factors. Our objective was to create such a model. Methods A prospective observational study was performed on consecutive eligible consenting burns patients. Demographic data, total burn surface area (TBSA), results of complete blood count, kidney function test, and arterial blood gas analysis were collected. The quantitative variables were compared using the unpaired student t -test/nonparametric Mann Whitney U-test. Qualitative variables were compared using the ⊠2-test/Fischer exact test. Binary logistic regression analysis was done and a logit score was derived and simplified. The discrimination of these models was tested using the receiver operating characteristic curve; calibration was checked using the Hosmer-Lemeshow goodness of fit statistic, and the probability of death calculated. Validation was done using the bootstrapping technique in 5,000 samples. A p -value of <0.05 was considered significant. Results On univariate analysis TBSA ( p <0.001) and Acute Physiology and Chronic Health Evaluation II (APACHE II) score ( p = 0.004) were found to be independent predictors of mortality. TBSA (odds ratio [OR] 1.094, 95% confidence interval [CI] 1.037-1.155, p = 0.001) and APACHE II (OR 1.166, 95% CI 1.034-1.313, p = 0.012) retained significance on binary logistic regression analysis. The prediction model devised performed well (area under the receiver operating characteristic 0.778, 95% CI 0.681-0.875). Conclusion The prediction of mortality can be done accurately at the bedside using TBSA and APACHE II score.

Keywords: APACHE II; burn-specific mortality; burns; mortality prediction; total burn surface area.

Fig. 1

Receiver operating characteristic ( ROC ) curve for the logit score and APACHE II–TBSA score (AT score). APACHE II, Acute Physiology And Chronic Health Evaluation II; TBSA, total burn surface area.

Fig. 2

Relationship between values of the APACHE II–TBSA score (AT score) and the observed mortality. APACHE II, Acute Physiology and Chronic Health Evaluation II; TBSA, total burn surface area.

Fig. 3

Contour plots for the logit score and APACHE II–TBSA score (AT score). APACHE II, Acute Physiology And Chronic Health Evaluation II; TBSA, total burn surface area.

Fig. 4

Comparison of the performance of the logit score, APACHE II–TBSA score (AT score) and fatality by longevity, APACHE II score, measured extent of burn, and sex (FLAMES) score for predicting 10-day, 20-day, and 30-day mortality. APACHE II, Acute Physiology And Chronic Health Evaluation II; TBSA, total burn surface area.