A number of recent studies have compared patient outcomes at specialty or high-volume hospitals vs outcomes at more traditional, nonspecialty “community” hospitals. MacKenzie et al2
compared outcomes of trauma patients treated at Level I Trauma centers with those treated at large nontrauma-designated hospitals, and found that in-hospital mortality and 1-year mortality was significantly decreased at designated level I trauma centers. A study of Florida trauma centers likewise found improved outcomes with regionalization of trauma care and despite higher costs at trauma centers the authors noted that the cost per life year saved was comparable with other major health problems such as breast cancer and coronary artery disease.3
Extensive work done by Birkmeyer et al4–6
has documented improved outcomes for a number of major general surgical and cardiothoracic7
procedures done at larger volume hospitals.
Given the complexity of NSTI infections and their need for aggressive surgical and prolonged critical care management, NSTIs may be similarly best managed at centers capable of providing this specialized care. Trends in the incidence of NSTIs are unclear, as the Centers for Disease Control stopped surveillance for these infections in 1991 and has only recently undertaken efforts to reclassify invasive streptococcal infections as notifiable diseases.10–12
Previous studies have examined increased burn center involvement in the care of patients with NSTIs.1
In this study, we sought to examine the patient and injury factors associated with treatment at burn centers and to determine if outcomes differed between burn and nonburn centers.
The majority of patients with NSTIs in this analysis received their definitive care at nonburn centers. However, patients at burn centers were much more likely to have been transferred from another institution. Within burn centers, patients transferred from another facility had significantly higher mortality than those not transferred, even after adjusting for other factors. This suggests that the cohort of patients requiring transfer to burn centers may be a higher-risk population.
Patients treated at burn centers had higher overall average lengths of stay, number of surgical procedures, hospital charges, and mortality rates. All of these would seem to be markers for greater disease severity, but attempts to quantify disease severity independent of treatment proved difficult. There was no information in the discharge data on physiologic measures such as shock, nor on the extent of the wounds. However, patients undergoing large numbers of procedures (4 or greater) were significantly more likely to be treated at a burn center. One could theorize that patients needing more frequent trips to the operating room may have more severe and extensive disease. The mortality rate at burn centers for NSTI in this database was consistent with rates previously reported at individual centers.1,13–15
The mortality at nonburn centers was significantly less than not only the burn centers in our study, but also lower than most reported mortality data in the literature. This further suggests that patients treated at burn centers were more severely ill.
Payer status was also found to be an independent predictor of treatment location. Self-pay patients and especially Medicaid patients were more likely to be treated at burn centers. This raises the specter that transfer to a burn center may have been motivated, in part, by payer status as has been found in recent studies of treatment of trauma and burn patients.16,17
In addition, Medicaid payer status was an independent predictor of mortality at burn centers. There was no evidence in our data that patients insured by Medicaid had less intensive or aggressive care for their NSTI. This association may be due, instead, to delays in seeking care because of worse healthcare access,18
or higher rates of comorbidities in poorer patients.19
A principal limitation of this and other large administrative databases is the lack of specific indicators of patient condition. For instance, we could not retrieve specific laboratory values, which can be useful in scoring systems such as the APACHE scores. Although the number of surgical procedures was available, it was impossible to assess the extent (eg, in square centimeters) of debridement. We attempted to use ICD-9 codes for various organ failure as markers for disease severity, as was done in other outcomes research.9
Higher numbers of organs in failure correlated with increased mortality in both patient cohorts in this study, and further study of this trend could help establish a scoring system for predicting mortality in patients with NSTIs and organ failure.
An additional limitation is that burn centers were self-identified, without regard to verification by the American Burn Association. We hypothesized that transferring hospitals would not be referring based on burn verification status but by whether the receiving hospital purported to have resources available for care of patients with extensive wounds. Self-identified burn centers may not meet established guidelines for quality of burn care, and may actually include centers that see predominately burns and are less experienced in the care of NSTIs.