An evaluation of risk factors for mortality after burn trauma and the identification of gender-dependent differences in outcomes

BACKGROUND: The primary objective of this study was to determine an objecti ve method for estimating the risk of mortality after burn trauma, and secon darily, to evaluate the relationship between gender and mortality, in the s etting of a quantifiable inflammatory stimulus. Previously reported estimat es of mortality risk after burn trauma may no longer be applicable, given t he overall reduction in case-fatality rates after burn trauma. We expect th at future advances in burn trauma research will require careful and ongoing quantification of mortality risk factors to measure the importance of newl y identified factors and to determine the impact of new therapies. Conflict ing clinical reports regarding the impact of gender on survival after sepsi s and critical illness may in part, be from different study designs, patien t samples, or failure to adequately control for additional factors contribu ting to the development of sepsis and mortality. STUDY DESIGN: Data from the prospectively maintained burn registry for pati ents admitted to the Parkland Memorial Hospital burn unit between January 1 , 1989 and December 31, 1998 were analyzed. Logistic regression was used to generate estimates of the probability of death in half of the study sample , and this model was validated on the second half of the sample. Risk facto rs evaluated for their relationship with mortality were: age, inhalation in jury, burn size, body mass (weight), preexisting medical conditions, nonbur n injuries, and gender. RESULTS: Of 4,927 patients, 5.3% died. The best model for estimating mortal ity included the percent of total body surface area burned; the percent of full-thickness burn size; the presence of an inhalation injury; age categor ies of: <30 years, 30 to 59 years, <greater than or equal to>60 years; and gender. The risk of death was approximately two-fold higher in women aged 3 0 to 59 years compared with men of the same age. CONCLUSIONS: We have provided a derailed method for estimating the risk of mortality after burn trauma, based on a large, contemporary cohort of patie nts. These estimates were validated on a second sample and proved to predic t mortality accurately. We have identified an increased mortality risk in w omen of 30 to 59 years of age. (J Am Coll Surg 2001;192:153-160. (C) 2001 b y the American College of Surgeons).