In this study based on the Healthcare Cost and Utilization Project Nationwide Inpatient Sample, we found that trauma patients with HAIs are at increased risk for mortality, have longer LOS, and incur higher inpatient costs. In particular, trauma patients with sepsis had a 6-fold higher risk of mortality, whereas patients with other HAIs had a nearly 1.5- to 2-fold higher mortality compared with patients without an HAI. Furthermore, patients with HAIs had LOS and inpatient costs that were approximately 2-fold higher than patients without HAIs.
Reducing HAIs is one of the top priorities in the efforts by the federal government and nongovernmental entities to improve patient safety and health care outcomes in the United States. In particular, the US Department of Health and Human Services has established a national agenda for HAI prevention in an Action Plan that outlines a strategy to reduce the incidence of HAIs by 75% over a 5-year period.25
Furthermore, in this action plan, methicillin-resistant Staphylococcus aureus
and CDAD acquired in the acute hospital setting have been identified as priority areas. The National Quality Forum has identified the prevention of health care–associated infections as a key area for improving patient safety in its list of Safe Practices for Better Healthcare
Three of the 6 recommended practices in the Institute for Healthcare Improvement’s 100 000 Lives Campaign are focused on the prevention of HAIs.27
Mandatory public reporting of hospital HAI rates is becoming more widespread as part of the effort to increase transparency and accountability to achieve reductions in HAIs.28–30
Finally, the Centers for Medicare and Medicaid Services is no longer reimbursing hospitals for some HAIs as part of the legislatively mandated initiative to penalize hospitals for hospital-acquired conditions.31–33
To our knowledge, our study is the first population-based epidemiologic study of HAIs in trauma patients using a large nationally representative database. Many of the previous studies on trauma patients with HAIs have focused on identifying risk factors for the development of HAIs.9,34–42
Other studies have described the epidemiologic features of HAI in the trauma patients7,43–48
Our findings confirm the findings of previous studies that HAIs in trauma patients are associated with increased mortality,36
In 2 of these previous studies, researchers did not find an independent association between HAI and mortality.45,47
All of these prior studies were relatively small and all were single-center studies, limiting the generalizability of their findings.
There are several important limitations to our study. First, administrative data are not as accurate as clinical records and do not capture all instances of HAIs. However, the accuracy of administrative data for identifying cases of sepsis has been validated in a previous epidemiologic study.13
For pneumonias, ICD-9-CM
codes demonstrate high specificity for the detection of pneumonias, but the sensitivity is approximately 50%. The accuracy of ICD-9-CM
codes for detecting cases of Staphylococcus
infections and CDAD is largely unknown.15,16
The undercoding of other hospital-acquired complications using administrative data has been confirmed in validation studies of the Agency for Healthcare Research and Quality Patient Safety Indicators.49
The undercoding of HAIs may be a source of bias in our analysis and may lead us to underestimate the impact of HAIs on outcomes if a significant number of patients with HAIs are included in the reference population of patients without HAIs.
Second, the use of the Trauma Mortality Probability Model may not have completely adjusted for disease severity because of the lack of information on patient physiology in administrative data.20
The Trauma Mortality Probability Model–ICD-9
is based on ICD-9-CM
injury codes but does not include important information on patient physiology such as Glasgow Coma Scale scores and vital signs on hospital admission. However, the statistical performance of the Trauma Mortality Probability Model–ICD-9
is excellent, minimizing the potential for omitted variable bias.20
Third, we were unable to explore the impact of HAIs on other important quality domains such as functional outcomes because these outcome data are not included in administrative data. Future work exploring the impact of HAIs on other quality domains will be necessary once these additional outcomes data become available.
Third, the Nationwide Inpatient Sample does not allow us to determine whether infections identified as HAIs were present on admission or developed as a complication of the hospital stay. Therefore, it is possible that some of the infections represent community-acquired infections as opposed to HAIs. However, it is likely that most infections in trauma patients are hospital acquired. Although this is a reasonable assumption for trauma patients, we were not able to verify this assumption because of the absence of a present-on-admission indicator in the Nationwide Inpatient Sample. Despite these limitations, to our knowledge, this study is the first analysis of the impact of HAIs in trauma patients using a large nationally representative database. Although it shares many of the same limitations of other epidemiological investigations conducted using large administrative data sets, it has the advantage of a large sample size not possible in studies based on prospectively collected clinical data.
Finally, our estimate of the association between HAIs and LOS may overestimate the effect of HAI on LOS. A priori, patients who develop HAIs would be expected to have longer LOS. However, patients who stay longer in the hospital would also be expected to be at higher risk of developing HAIs. As a result, the estimated correlation may overstate the influence of HAI on LOS. Statistical techniques to deal with this problem of endogeneity between LOS and HAIs, ie, the use of instrumental variables, would not be feasible here. This limitation is partially offset because the LOS model includes many of the important determinants of LOS. This same issue applies to the association between HAIs and cost because the LOS is an important element of cost. The practical impact of this bias from a policy perspective is lessened by the fact that policies designed to reduce the likelihood of HAIs could also include efforts to reduce LOS.
In summary, HAIs are associated with increased mortality, LOS, and inpatient costs in patients admitted with traumatic injuries. In light of the preventability of many hospital-acquired conditions50,51
and the magnitude of the clinical and economic burden of HAIs, the current emphasis on implementing interventions aiming to decrease the incidence of HAIs may have a potentially large impact. The current shift in payment policies away from “output-based funding” toward “outcomes-based funding” may act as a catalyst for patient safety initiatives designed to reduce HAIs and improve patient outcomes.32
Future studies will be necessary to assess the impact of recent changes in Centers for Medicare and Medicaid Services payment policies on the incidence of HAIs.