Objectives

Determine the relationship between the volume of burn admissions and outcomes for children with burns.

Design

Retrospective review of the National Burn Repository from 2000-2009 using mixed effect logistic regression modeling.

Setting

Tertiary burn centers in the United States.

Patients

All children <18 years of age admitted with burn injury to a burn center submitting data to the National Burn Repository.

Interventions

None.

Measurements and main results

Of the 210,683 records in the NBR from 2000-2009, 33,115 records for children ≤ 18 years of age met criteria for analysis; 26,280 had burn sizes smaller than 10%; only 32 of these children died. Volume of children treated varied greatly among facilities. Age, total body surface area burn, inhalation injury, and burn center volume influenced mortality (p < 0.05) An increase in the median yearly admissions of 100 decreased the odds of mortality by approximately 40%. High volume centers (admitting >200 pediatric patients/year) had the lowest mortality when adjusting for age and injury characteristics (p < 0.05).

Conclusions

Higher volume pediatric burn centers had lower mortality, particularly at larger burn sizes. The lower mortality of children a high volume centers could reflect greater experience, resource, and specialized expertise in treating pediatric patients.

Traditional burn mortality models are derived using all age groups. We hypothesized that age variably impacts mortality after burn and that age-specific models for children, adults, and seniors will more accurately predict mortality than an all-ages model. We audited data from the American Burn Association (ABA) National Burn Repository (NBR) from 2000 to 2009 and used mixed effect logistic regression models to assess the influence of age, total body surface area (TBSA) burn, and inhalation injury on mortality. Mortality models were constructed for all ages and age-specific models: children (<18 years), adults (18-60 years), and seniors (>60 years). Model performance was assessed by area under the receiver operating curve (AUC). Main effect and two-way interactions were used to construct age-group specific mortality models. Each age-specific model was compared to the All Ages model. Of 286,293 records 100,051 had complete data. Overall mortality was 4% but varied by age (17% seniors, <1% children). Age, TBSA, and inhalation injury were significant mortality predictors for all models (p<0.05). Differences in predicted mortality between the All Ages model and the age-specific models occurred in children and seniors. In the age-specific pediatric model, predicted mortality decreased with age; inhalation injury had greater effect on mortality than in the All Ages model. In the senior model mortality increased with age. Seniors had greater increase in mortality per 1% increment in burn size and 1 year increase in age than other ages. The predicted mortality in seniors using the senior-specific model was higher than in the All Ages model. "One size fits all" models for predicting burn outcomes do not accurately reflect the outcomes for seniors and children. Age-specific models for children and seniors may be advisable.

Hospital length of stay (LOS) after burn injury is commonly estimated as 1 day per percent burn, but LOS often exceeds that estimate. The purpose of this study is to develop a novel method for estimating burn hospital LOS at any time during hospitalization. The authors used the American Burn Association National Burn Repository from 2000 to 2009 to directly estimate the median residual LOS (MRLOS) of patients hospitalized for burn injuries and who survived to discharge. The MRLOS is the median of how many more days a burn patient will be hospitalized given that the person has been in hospital for a specified time period. The authors also estimated the 25th and 75th percentiles of residual life and quantified the relationship between MRLOS and LOS with ordinary least squares for all burn patients, by burn size and by presence of inhalation injury. MRLOS increased with increasing LOS, confirming that discharge estimates change over time. Patients with inhalation injury had longer MRLOS than patients without inhalation injury in the first 100 hospital days. Patients with large burns (>25%) had large MRLOS consistent with prolonged hospitalization, but patients with small burns (<25%) also had steadily increasing MRLOS during hospitalization (ie, the longer the patient was in the hospital, the longer the predicted LOS regardless of initial LOS estimate). Estimating remaining hospital LOS at any time during admission has been problematic; MRLOS can be used to provide an estimate of remaining hospital LOS and resource utilization to families, administrators, and other medical professionals.

Importance

Current outcome predictors for illness and injury are measured at a single time point-admission. However, patient prognosis often changes during hospitalization, limiting the usefulness of those predictions. Accurate depiction of the dynamic interaction between competing events during hospitalization may enable real-time outcome assessment.

Objective

To determine how the effects of burn outcome predictors (ie, age, total body surface area burn, and inhalation injury) and the outcomes of interest (ie, mortality and length of stay) vary as a function of time throughout hospitalization.

Design, setting, and participants

In this retrospective study, we used the American Burn Association's National Burn Repository, containing outcomes and patient and injury characteristics, to identify 95 579 patients admitted with an acute burn injury to 80 tertiary American Burn Association burn centers from 2000 through 2009. We applied competing risk statistical methods to analyze patient outcomes.

Main outcomes and measures

We estimated the cause-specific hazard rates for death and discharge to assess how the instantaneous risk of these events changed across time. We further evaluated the varying effects of patient age, total body surface area burn, and inhalation injury on the probability of discharge and death across time.

Results

Maximum length of stay among patients who died was 270 days and 731 days among those discharged. Total body surface area, age, and inhalation injury had significant effects on the subdistribution hazard for discharge (P < .001); these effects varied across time (P < .002). Burn size (coefficient -0.046) determined early outcomes, while age (coefficient -0.034) determined outcomes later in the hospitalization. Inhalation injury (coefficient -0.622) played a variable role in survival and hospital length of stay.

Conclusions and relevance

Real-time measurement of dynamic interrelationships among burn outcome predictors using competing risk analysis demonstrated that the key factors influencing outcomes differed throughout hospitalization. Further application of this analytic technique to other injury or illness types may improve assessment of outcomes.