Burn Outcomes at Extremes of Body Mass Index- Underweight is as problematic as Morbid Obesity

The association between body mass index and physical function in adult burn survivors: A Burn Model System National Database study

INTRODUCTION

An area of rehabilitation research in burns is the impact of co-morbidities on disease trajectory. Obesity is a comorbidity of increasing public health concern, but its role remains controversial regarding burn injury and physical recovery. Our aim was to evaluate the association between body mass index (BMI) categories as a measure of obesity at discharge and self-reported physical function (PF) during recovery of adult burn survivors.

METHODS

This is a retrospective study on data collected by four major US burn centers, which contribute to the Burn Model System National Database. The data included BMI obtained at hospital discharge and self-reported PF-mobility, using the PROMIS measures assessed at 6, 12, and 24 months after burn. Subjects were classified into weight status categories based on BMI: underweight (BMI <18.5), normal weight (18.5 ≤ BMI <25), overweight (25 ≤ BMI <30), obesity class 1 (30 ≤ BMI <35), obesity class 2 (35 ≤ BMI <40), and obesity class 3 (BMI ≥40). Mixed-effects linear regression models were used to assess the association between BMI categories and PF scores over time, adjusted for patient and injury characteristics.

RESULTS

A total of 496 adult burn patients aged 47 ± 16 years were included, with mean total body surface area (TBSA) burned of 18 ± 19 % and mean BMI at discharge of 28 ± 7 kg/m2. PROMIS PF scores significantly improved over time in the recovery phase after burn (time effect, p < 0.001). Compared to overweight burn patients, normal-underweights exhibited lower PF score by an average of 4.06 units (p = 0.001) but scores increased linearly by an estimated 0.17 units per month (p = 0.01) over the 24 months after discharge. Similarly, compared to overweight burn patients, class 1 obese reported lower PF score by a mean 2.67 units (p = 0.07) but PF increased linearly by 0.15 units per month (p = 0.07) over the 24 months after discharge. These findings were independent of the effects of age at discharge, sex, TBSA burned, and hand and leg burn.

CONCLUSION

Being overweight was associated with improved and faster recovery of PF scores compared to normal, underweight, and obese burn patients during long-term recovery. Hence, our data suggests that long-term recovery and restoration of PF in adult burn survivors is not compromised by a small excess in body weight.

Baseline glucose levels moderate the association between burn-related mortality inpatients with obesity

BACKGROUND

Differing findings concerning outcomes for burn patients with obesity indicate additional factors at play. One possible explanation could lie in determining metabolically healthy versus unhealthy obesity, which necessitates further study.

METHODS

A retrospective study was conducted using the Cerner Health Facts® Database. Deidentified patient data from 2014 to 2018 with second or third-degree burn injuries were retrieved. A moderator analysis was conducted to determine if the association between increased body mass index (BMI) and mortality is moderated by baseline glucose level, a surrogate marker associated with metabolically unhealthy obesity.

RESULTS

The study included 4682 adult burn patients. BMI alone was not associated with higher mortality (β = 0.106, p = 0.331). Moderation analysis revealed that baseline glucose level significantly modulated the impact of BMI on burn-related obesity; patients with higher BMI and higher baseline blood glucose levels had higher mortality than those with lower baseline blood glucose levels (β = 0.277, p = 0.009). These results remained unchanged after adjusting for additional covariates (β = 0.285, p = 0.025) and inthe sensitivity analysis.

CONCLUSIONS

Increased baseline glucose levels indicate increased mortality in obese patients with burn injuries, emphasizing the differentiation between metabolically unhealthy versus healthy obesity.

Examining Obesity and Its Association With Burn Injury: A Secondary Analysis of the Transfusion Requirement in Burn Care Evaluation Study

INTRODUCTION

Literature examining the connection between obesity and burn injuries is limited. This study is a secondary analysis of a multicenter trial data set to investigate the association between burn outcomes and obesity following severe burn injury.

MATERIALS AND METHODS

Body mass index (BMI) was used to stratify patients as normal weight (NW; BMI 18.5-25), all obese (AO; any BMI>30), obese I (OI; BMI 30-34.9), obese II (OII; BMI 35-39.9), or obese III (OIII; BMI>40). The primary outcome examined was mortality. Secondary outcomes included hospital length of stay (LOS), number of transfusions, injury scores, infection occurrences, number of operations, ventilator days, intensive care unit LOS, and days to wound healing.

RESULTS

Of 335 patients included for study, 130 were obese. Median total body surface area (TBSA) was 31%, 77 patients (23%) had inhalation injury and 41 patients died. Inhalation injury was higher in OIII than NW (42.1% versus 20%, P = 0.03). Blood stream infections (BSI) were higher in OI versus NW (0.72 versus 0.33, P = 0.03). Total operations, ventilator days, days to wound healing, multiorgan dysfunction score, Acute Physiology and Chronic Health Evaluationscore, hospital LOS, and intensive care unit LOS were not significantly affected by BMI classification. Mortality was not significantly different between obesity groups. Kaplan-Meier survival curves did not significantly differ between the groups (χ2 = 0.025, P = 0.87). Multiple logistic regression identified age, TBSA, and full thickness burn as significant independent predictors (P < 0.05) of mortality; however, BMI classification itself was not predictive of mortality.

CONCLUSIONS

No significant association between obesity and mortality was seen after burn injury. Age, TBSA, and percent full- thickness burn were independent predictors of mortality after burn injury, while BMI classification was not.

Impact of elevated body mass index on burn injury-associated mortality in a representative US sample

BACKGROUND

The impact of obesity on burn-related mortality is inconsistent and incongruent; despite being a risk factor for numerous comorbidities that would be expected to increase complications and worsen outcomes, there is evidence of a survival advantage for patients with high body mass index-the so-called obesity paradox. We used a national data set to explore further the relationship between body mass index and burn-related mortality.

METHODS

Deidentified data from patients with second and third-degree burns between 2014 and 2018 were obtained from the Cerner Health Facts Database. Univariate and multivariate regression models were created to identify potential factors related to burn-related mortality. A restricted cubic spline model was built to assess the nonlinear association between body mass index and burn-related mortality. All statistical analyses were conducted using R (R Foundation for Statistical Computing).

RESULTS

The study included 9,405 adult burn patients. Univariate and multivariate analyses revealed that age (odds ratio = 2.189 [1.771, 2.706], P < .001), total burn surface area (odds ratio = 1.824 [1.605, 2.074], P < .001), full-thickness burns (odds ratio = 1.992 [1.322, 3.001], P < .001), and comorbidities (odds ratio = 2.03 [1.367, 3.014], P < .001) were associated with increased mortality. Sensitivity analysis showed similar results. However, a restricted cubic spline indicated a U-shaped relation between body mass index and burn-related mortality. The nadir of body mass index was 28.92 kg/m², with the lowest mortality. This association persisted even after controlling for age, total burn surface area, full-thickness burns, and comorbidities, which all remained significant.

CONCLUSION

This study confirms a U-shaped association between body mass index and burn-related mortality along with age, total burn surface area, full-thickness burns, and comorbidities as risk factors.

The role of biodegradable temporizing matrix in the management of a patient with major burns and anorexia nervosa

Severe malnutrition secondary to anorexia nervosa results in deeper burns and significantly impacts wound healing, which represents a major challenge to burn management. The use of acellular dermal matrices, such as biodegradable temporizing matrix (BTM), is a valuable tool to overcome the surgical limitations. We describe a case of a 36-year-old female with a background of anorexia nervosa (body mass index of 12.3) presenting with a 30% total burns surface area (TBSA) burn. All of her burns were excised down to fascia due to the absence of subcutaneous fat. Her thin skin and depleted nutritional status significantly impacted reconstructive options. BTM was utilized to create a neodermis and provide adequate time to optimize the nutritional status before autologous skin resurfacing 3 weeks later, which yielded robust coverage with minimal donor site morbidity. Despite initial surgical and nutritional challenges, excellent outcomes were achieved in terms of wound healing, scar contractures and mobility.