Validation of the prognostic burn index: A nationwide retrospective study

Abstract

BackgroundThe burn index (BI=full thickness total burn surface area [TBSA]+1/2 partial thickness TBSA) and prognostic burn index (PBI=BI+age) are clinically used particularly in Japan. However, few studies evaluated the validation of PBI with large sample size. We retrospectively investigated the relationships between PBI and mortality among burn patients using data from a nationwide database. MethodsData of all burn patients with burn index ≥1 were extracted from the Japanese Diagnosis Procedure Combination (DPC) inpatient database from 1 July 2010 to 31 March 2013 (17,185 patients in 1044 hospitals). The primary endpoint was all-cause in-hospital mortality. ResultsOverall in-hospital mortality was 5.9% (1011/17,185). Mortality increased significantly as the PBI increased (Mantel-Haenszel trend test, P<0.001). The area under the receiver operating characteristic curve for PBI was 0.90 (95%CI, 0.90–0.91), and a PBI above a threshold of 85 showed the highest association with in-hospital mortality. Logistic regression analysis showed that PBI≥85 (odds ratio (OR), 14.6; 95%CI, 12.1–17.6), inhalation injury with mechanical ventilation (OR, 13.0; 95%CI, 10.8–15.7), Charlson Comorbidity Index≥2 (OR, 1.8; 95%CI, 1.5–2.3), and male gender (OR, 1.5; 95%CI, 1.3–1.8) were significant independent risk factors for death. ConclusionsOur study suggested that a PBI above a threshold of 85 was significantly associated with mortality. The PBI and mechanical ventilation were the most significant factors predicting in-hospital mortality, after adjustment for inhalation injury, comorbidity, and gender.