Gender has no influence on mortality after burn injuries: A 20-year single center study with 839 patients

Highlights

• The higher risk among women was apparent only in univariate regression analysis.

• Gender-specific differences diminished after adjusting for confounding factors.

• Age, %TBSA, inhalation injury, full-thickness burn were predictors of mortality.

• To conclude, women and men had the same risk of death in our study cohort.

Abstract

Background

According to the ABSI – Abbreviated Burn Severity Index – women exhibit an increased risk of succumbing to burn injuries. In contrast, following non-thermal trauma, increased mortality has been shown for the male gender. Therefore, the purpose of this study was to evaluate gender-specific differences among burn patients with special regard to burn mortality.

Methods

We retrospectively studied 839 patients who were admitted to the Burn Intensive Care Unit (BICU) and underwent surgical treatment between June 1994 and December 2014. In-hospital mortality was the main clinical endpoint. Odds ratios (ORs) were calculated using univariate and multivariate logistic regression models for the association between sex and mortality.

Results

In total, we included 530 male and 309 female burn patients. All patients had at least partial-thickness burns and underwent one or more operative procedures. Women were significantly older than men (mean 60.0 years vs 46.2 years; p < 0.001). Despite having smaller injuries (24.6% vs 30.3% total body surface area (TBSA); p < 0.001), burn mortality among women significantly differed from that of men (27.8% vs 21.7%; OR 1.39, p = 0.045, 95% CI 1.01–1.92). This association, however, did not persist after adjusting for age, %TBSA, inhalation injury and full-thickness burns (OR 1.07, p = 0.77, 95% CI 0.68–1.70).

Conclusions

Despite increasing research directed at women’s health, the assoziation between gender and burn mortality has yielded conflicting results. This study does not support a gender-specific difference in burn mortality in our study population.

Introduction

Despite advances in injury prevention programs and precautionary measures, burn injuries still represent the fourth most common type of trauma following traffic accidents, falls and interpersonal violence [1], [2]. In Europe, the annual incidence lies between 2 and 29 per 100.000 individuals [3]. Although the majority of burns are minor, they can also lead to life-threating injuries. Time to hospital admission and pre-existing co-morbidities are only some variables of the list of known risk factors which influence patients’ outcome. The following prognostic determinants have been commonly described in the literature: patients’ age, burn size and the presence of inhalation injury [4]. These three variables are commonly used in scoring systems, which find broad acceptance to make objective estimates about burn outcome and thereby facilitate and guide treatment decisions in everyday clinics [5].

Gender as a decisive factor in burn mortality was already described in 1982 when the Abbreviated Burn Severity Index (ABSI) was introduced by Tobiasen et al. [6]. The ABSI was the first burn-specific outcome scoring system which incorporated gender in its prediction attributing females a higher likelihood of death compared to similarly injured men. Within constant development in burn care and changes in patients’ demographics, it became necessary to re-validate its predictive accuracy. According to Forster et al, the ABSI can be regarded as a valuable model in modern burn medicine but gender was found to be the weakest predictive value compared to other variables [7]. Notably, the most widely used scoring systems like the Revised Baux score and the Boston score do not include gender in their prediction [8], [9]. In addition to this, when McGwin et al. compared data from multiple burn centers across the United States gender was not incorporated in their final prediction model [10].

Despite the increasing evidence that gender significantly influences survival in other fields of medicine, as was shown for trauma-hemorrhagic shock or ICU-acquired infections with a more favorable outcome for (especially young) women, studies in burn research have so far shown inconsistent results regarding gender dimorphism in outcome analysis [3], [11], [12]. Numerous studies confirmed female sex to be a negative predictor in burn outcome, although this association varied markedly from an 1.4 up to 9-fold increase of burn mortality compared with similarly injured men [13], [14], [15]. In addition to this, some authors identified gender dimorphism to become most apparent in patients younger than 60 years, or rather at ages when women can be regarded to be premenopausal. These observations generally suggest a hormonal explanation for the increased risk of women to succumbing to burn injuries [16], [17], [18], [19]. Other studies, however, identified gender dimorphism to be significant only among the elderly or the pediatric group, which stands in contrast to the results mentioned before [20], [21]. There are several investigations which did not show any difference in burn mortality between men and women, neither among the young nor among the elderly population [22], [23], [24].

The understanding of how gender affects survival following burn injury is a vital and necessary step towards developing novel therapeutic interventions. Therefore − and due to the fact that there is only a limited amount of data about the relationship between gender and burn outcome in Europe − our aim was to reconsider the influence of gender on survival after burn injuries in a single center study.