Cohort analysis of 50% lethal area (LA50) and associating factors in burn patients based on quality improvements and health policies
Authors: Shahriarirad Reza , Shekouhi Ramin , Nabavizadeh Sara Sadat , Zardosht Mitra , Tadayon Seyed Mohammad Kazem , Ahmadi Meysam , Keshavarzi Abdolkhalegh 
Published: November 2023

Burn injuries are among the common traumatic injuries, which can be accompanied with lifelong morbidity and mortality. The Lethal Area Fifty Percent (LA50) index is another reliable outcome measurement tool that assesses the standard of medical care at burn centers. It is widely used as a benchmark for assessing the quality of burn care and is considered the percentage at which 50% of burn patients are expected to die because of burn-related injuries. We aimed to determine and compare the LA50 in burn patients admitted to Shiraz Burn Referral Centers in 2018–2021 and 2011–2018 with regard to improving the quality of special care and infection control in the new hospital. We conducted a retrospective cohort analysis on patients admitted to Amir al-Momenin Burn Injury Hospital in Shiraz, Fars, Southern Iran. Data were retrospectively gathered from March 2011 to January 2022, and subsequently analyzed with standard statistical analysis, and also multivariate and probability analysis. A total of 7382 patients with acute burns injuries were identified. Among them, 4852 (65.7%) patients were men, and the median age was 27 years [Q1–Q3 7–40; range 1–98]. Most of the patients were in the pediatric and early adulthood age range, with 76.2% being younger than 40 years old. The median TBSA was 24% [IQR 14, 43], and the median duration of hospitalization was 11 [IQR 11] days. Most injuries were secondary to flame and fire (33.5%; n = 2472). The mortality rate in our study was 19.0% (n = 1403). We evaluated our patients based on two main time intervals: March 2011 till February 2018 (n = 3409; 46.2%), and March 2018 to January 2022 (n = 3973; 53.8%). Based on multivariate analysis, the second interval of our study was significantly correlated with a more female patients, higher age, lower TBSA, less burn injuries due to scald, contact, but more frequent fire and flame injuries, and also lower mortality rate. Factors correlated with higher mortality included male gender, older age, shorter hospitalization duration, higher TBSA, etiology of fire and flame, and accidental burn injuries. A Baux score of 76.5 had a sensitivity of 81.1%, specificity of 87.3%, accuracy of 86.1% in predicting mortality among our patients. The mortality probability for the study intervals were 20.67% (SD 33.0%) for 2011–2018, and 17.02% (SD 29.9%) for 2018–2022 (P < 0.001). The LA50 was 52.15 ± 2 for all patients. This ammount was 50 ± 2% in 2011–2018, and 54 ± 2 in 2018–2022 (P < 0.001). The mean LA50 values showed significant improvements following significant modifications in our critical care for burn victims, including augmented intensive care unit capacity, prompt relocation of inhalation burn cases to the intensive care unit, establishing a well-trained multidisciplinary team, and improved infection control. To improve outcomes for burn patients in developing countries, major changes should be made in the management of burn patients and LA50 is a reliable assessment tool for evaluating the how these changes affect patient’s outcomes.