Burn mechanism does not predict ICU mortality beyond the Abbreviated Burn Severity Index: A 24-year registry analysis

Flame burns are consistently associated with higher mortality than scald injuries; however, it is unclear whether burn mechanism independently influences outcome or primarily reflects differences in injury severity. Therefore, we performed a retrospective analysis of a prospectively maintained registry by including 1069 adult patients with flame or scald burns who were admitted to a tertiary burn intensive care unit between 2000 and 2024. The primary outcome was intensive care unit (ICU) mortality. Logistic regression analyzes evaluated the association between burn mechanism and mortality before and after adjustment for Abbreviated Burn Severity Index (ABSI) and calendar year, with an additional model incorporating the individual ABSI components and calendar year. Patients with flame burns had significantly larger burns, higher ABSI scores, more frequent inhalation injury, and higher prevalence of full-thickness burns (all p < 0.001). Crude ICU mortality was significantly higher following flame burns than scald injuries (27.8% vs. 10.3%; OR 3.36, 95% CI 2.26-5.01; p<0.001). However, burn mechanism was no longer independently associated with mortality after adjusting for ABSI and calendar year (OR 1.03, 95% CI 0.63-1.69; p=0.913) or after adjusting for the individual ABSI components and calendar year (OR 0.99, 95% CI 0.57-1.71; p=0.967). Age, total body surface area burned, inhalation injury, and full-thickness burns remained independently associated with mortality. These findings indicate that the higher mortality observed after flame burns is attributable to greater injury severity rather than burn mechanism. Therefore, burn mechanism should be regarded primarily as a marker of injury severity rather than an independent predictor of ICU mortality, thereby reinforcing the importance of validated severity scores for prognostic assessment.