Inhalation Injury Severity Score on Admission Predicts Overall Survival in Burn Patients

Inhalation injury is diagnosed in up to one-third of burn patients and is associated with increased morbidity and mortality. There are multiple scoring systems to grade inhalation injury, but no study has evaluated the ability of these scoring systems to predict outcomes of interest such as overall survival. We conducted a prospective, observational study of 99 intubated burn patients who underwent fiberoptic bronchoscopy within 24 hr of admission and graded inhalation injury using three scoring systems: abbreviated injury score (AIS), inhalation injury severity score (I-ISS), and mucosal score (MS). Agreement between scoring systems was assessed with Krippendorff's alpha (KA). Multivariable analyses were conducted to determine if variables were associated with overall survival. At admission, median AIS, I-ISS, and MS scores were 2 for all scoring systems. Patients who died had higher overall injury burden than those who survived and had similar median admission AIS and MS scores, but higher I-ISS scores. There was strong correlation between the inhalation injury grade at admission using the three scoring systems (KA = 0.85). On regression analysis, the only scoring system independently associated with overall survival was I-ISS (score 3 compared to scores 1-2: OR 13.16, 95% CI 1.65-105.07; P = .02). Progression of injury after initial assessment may contribute to the poor correlation between admission score and overall survival for injuries graded with AIS and MS. Repeated assessment may more accurately identify patients at increased risk for mortality.