Burn mortality in patients with preexisting cardiovascular disease.

Burn shock, a complex process, which develops following burn leads to severe and unique derangement of cardiovascular function. Patients with preexisting comorbidities such as cardiovascular diseases may be more susceptible. We therefore sought to examine the impact of preexisting cardiovascular disease on burn outcomes. A retrospective analysis of patients admitted to a regional burn center from 2002 to 2012. Independent variables analyzed included basic demographics, burn mechanism, presence of inhalation injury, TBSA, pre-existing comorbidities, and length of ICU/hospital stay. Bivariate analysis was performed and Poisson regression modeling was utilized to estimate the incidence of being in the ICU and mortality. There were a total of 5332 adult patients admitted over the study period. 6% (n=428) had a preexisting cardiovascular disease. Cardiovascular disease patients had a higher mortality rate (16%) compared to those without cardiovascular disease (3%, p<0.001). The adjusted Poisson regression model to estimate incidence risk of being in intensive care unit in patients with cardiovascular disease was 33% higher compared to those without cardiovascular disease (IRR=1.33, 95% CI=1.22-1.47). The risk for mortality is 42% higher (IRR=1.42, 95% CI=1.10-1.84) for patients with pre-existing cardiovascular disease compared to those without cardiovascular disease after controlling for other covariates. Preexisting cardiovascular disease significantly increases the risk of intensive care unit admission and mortality in burn patients. Given the increasing number of Americans with cardiovascular diseases, there will likely be a greater number of individuals at risk for worse outcomes following burn. This knowledge can help with burn prognostication.

Knowlin L ，Reid T ，Williams F ，Cairns B ，Charles A ... -  《-》

The measured effect magnitude of co-morbidities on burn injury mortality.

The ability to better prognosticate burn injury outcome is challenging and historically, most center use the Baux or revised Baux score to help prognosticate burn outcome, however, the weighted contribution of comorbidity on burn mortality has traditionally not been accounted for nor adequately studied. We therefore sought to determine the effect of comorbidities, using the Charlson comorbidity index (CCI) on burn mortality. The purpose of this study was to determine the effect of comorbidities on burn injury mortality as determined by the LA50 (lethal TBSA burn at which 50% of the cohort will succumb from the burn injury) in a retrospective analysis of patients admitted to a regional burn center from 2002 to 2012. Independent variables analyzed included basic demographics, burn mechanism, presence of inhalation injury, TBSA (total body surface area), length of hospital stay, and pre-existing comorbidities. Bivariate analysis was performed and logistic regression modeling using significant variables was utilized to estimate odds of death. 7640 patients were included in this study. Overall survival rate was 96%. 40% of our burn cohort had at least one comorbidity. There was a linear increase in the likelihood of death with an increase in CCI. The logistic regression model for mortality outcomes identified four statistically significant variables: age, TBSA, inhalational injury and the presence of comorbidities (OR=1.59 for each 1 point increase in CCI; 95% CI 1.44-1.77). The unadjusted LA50 was 53% for the entire cohort. Partial adjustment multivariate regression controlling for burn mechanism and inhalation injury only, produced a slight reduction in LA50 for the 0-18 and 19-64 age categories to 76% and 48% TBSA, respectively, but a significant decrease occurred in the ≥65 years age group with a reduced LA50 to 20% TBSA (p<0.001). After full adjustment for all significant covariates, including comorbidities, the independent magnitude of effect of comorbidities on the LA50 was evident in the <65 cohort. The full adjustment showed a LA50 decreased to 61% and 43% TBSA, respectively in the 0-18 and >18-65 age groups respectively (p<0.001), however, in the >65 years age cohort there was no change in the LA50. Preexisting comorbidities have a significant effect on burn injury mortality in all age groups, particularly the younger burn population. The measured effect of comorbidities in the >65 yr age cohort was mitigated by the co-linearity between age and comorbidities. The inclusion of CCI is imperative so as to better prognosticate burn outcome and help guide expectations and resource utilization, particularly in the younger burn cohort.

Knowlin L ，Stanford L ，Moore D ，Cairns B ，Charles A ... -  《-》

The effect of preexisting respiratory co-morbidities on burn outcomes.

Burns cause physiologic changes in multiple organ systems in the body. Burn mortality is usually attributable to pulmonary complications, which can occur in up to 41% of patients admitted to the hospital after burn. Patients with preexisting comorbidities such as chronic lung diseases may be more susceptible. We therefore sought to examine the impact of preexisting respiratory disease on burn outcomes. A retrospective analysis of patients admitted to a regional burn center from 2002-2012. Independent variables analyzed included basic demographics, burn mechanism, presence of inhalation injury, TBSA, pre-existing comorbidities, smoker status, length of hospital stay, and days of mechanical ventilation. Bivariate analysis was performed and Cox regression modeling using significant variables was utilized to estimate hazard of progression to mechanical ventilation and mortality. There were a total of 7640 patients over the study period. Overall survival rate was 96%. 8% (n=672) had a preexisting respiratory disease. Chronic lung disease patients had a higher mortality rate (7%) compared to those without lung disease (4%, p<0.01). The adjusted Cox regression model to estimate the hazard of progression to mechanical ventilation in patients with respiratory disease was 21% higher compared to those without respiratory disease (HR=1.21, 95% CI=1.01-1.44). The hazard of progression to mortality is 56% higher (HR=1.56, 95% CI=1.10-2.19) for patients with pre-existing respiratory disease compared to those without respiratory disease after controlling for patient demographics and injury characteristics. Preexisting chronic respiratory disease significantly increases the hazard of progression to mechanical ventilation and mortality in patients following burn. Given the increasing number of Americans with chronic respiratory diseases, there will likely be a greater number of individuals at risk for worse outcomes following burn.

Knowlin LT ，Stanford LB ，Cairns BA ，Charles AG ... -  《-》

Clinical outcomes after burns in elderly patients over 70 years: A 17-year retrospective analysis.

In the United Stated population >70years is likely to double by the year 2050. Elderly population (>70years) are most vulnerable to burns and outcomes following such injuries in this special group is poorly studied. This study aimed to look at outcomes following burns in patients >70years over a period of 17 years. Data on 6512 patients admitted to a Level I Burn Center between 1995 and 2011 was analyzed. Age, gender, ethnicity, TBSA, burn etiology, hospital and burn intensive care unit (ICU) length of stay (LOS) and status at discharge were abstracted. Three broad categories were created based on presence or absence of smoke inhalation, No smoke inhalation (Group A), smoke inhalation only (Group B) and smoke inhalation with burn injury (Group C). Differences were analyzed using the student's t-test for continuous variables and Chi-Square test for categorical variables. The study group was comprised of 564 patients, 72.3% in group A, 4.8% in group B and 22.9% in group C formed the study population. The mean age of the patients studied was 80.4±6.7, with female patients being more common (58%). The number of Caucasians (72.9%) was highest in group C compared to other racial groups (p=0.047). Majority of patients in the group B (59.3%) were admitted directly compared to other two groups (group A=24.0%, group B=34.9%, p<0.001). Overall percent total body surface area (% TBSA) and % TBSA third degree burns were higher in group C, whereas % TBSA second degree burns were common in group B (p<0.05). The number ICU admissions, the mean length of ICU stay, mean duration of ventilator support and mean length of hospitalization were all highest in group C patients (p<0.001). The number of discharges to home without home health aide were higher in group A, whereas the number of discharges to nursing home/rehabilitation/extended care facility were higher in group B (p<0.001). The in-hospital mortality (58.1%, p<0.001) and overall burn related mortality (62.8%, p<0.001) were highest in group C. There was no significant difference between the groups for the number of patients converted to hospice care (p=0.21). On multivariate analysis ICU admission (Odds Ratio [OR]=3.7, 95% Confidence Interval [95% CI]=2.1-6.5), ventilator support (OR=7.1, 95% CI=4.1-12.0), and %TBSA >10% (OR=3.1, 95% CI=1.9-5.0) significantly increased mortality. In terms of complications, group C had a significantly higher incidence of pneumonia (18.6%, p<0.001), respiratory failure (17.1%, p=0.001), and sepsis (7.8%, p=0.003). Patients >70 years constitute small (8.6%) but significant number among burn patients. The overall ICU admissions, number of days on ventilator, ICU stay, in-hospital mortality and overall mortality is higher in this group of population even for low % TBSA burns. Presence of smoke inhalation increases mortality.

Gregg D ，Patil S ，Singh K ，Marano MA ，Lee R ，Petrone SJ ，Chamberlain RS ... -  《-》

The effect of smoking status on burn inhalation injury mortality.

Three factors that effect burn mortality are age, total body surface of burn (TBSA), and inhalation injury. Of the three, inhalation injury is the strongest predictor of mortality thus its inclusion in the revised Baux score (age+TBSA+17* (inhalation injury, 1=yes, 0=no)). However, the weighted contribution of specific comorbidities such as smoker status on mortality has traditionally not been accounted for nor studied in this subset of burn patients. We therefore sought to examine the impact of current tobacco and/or marijuana smoking in patients with inhalation injury. A retrospective analysis of patients admitted to a regional burn center from 2002 to 2012. Independent variables analyzed included basic demographics, burn mechanism, presence of inhalation injury, TBSA, pre-existing comorbidities, and smoker status. Bivariate analysis was performed and logistic regression modeling using significant variables was utilized to estimate odds of mortality. There were a total of 7640 patients over the study period. 7% (n=580) of the burn cohort with inhalation injury were included in this study. In-hospital burn mortality for inhalation injury patients was 23%. Current smokers (20%) included cigarette smokers and marijuana users, 19% and 3%, respectively. Preexisting respiratory disease (17%) was present in 36% of smokers compared to 13% of non-smokers (p<0.001). Smokers had significantly lower mortality rate (9%) compared to non-smokers (26%, p<0.01). The logistic regression model for mortality outcomes identified statistically four significant variables: age, TBSA, ethnicity, and smoker status (OR=0.41, 95% CI=0.18-0.93). Presence of comorbidities, including preexisting respiratory disease, was not significant. In the sub group of burn patients with inhalation injury, the odds of mortality significantly decreased in pre-existing smokers after adjusting for significant covariates. We postulate that an immune tolerance mechanism that modulates and diminishes the pro-inflammatory response confers a survival advantage in smokers after exposure to acute smoke inhalation injury. Future prospective studies in human and/or animal models are needed to confirm these findings.

Knowlin L ，Stanford L ，Cairns B ，Charles A ... -  《-》