The study highlights important findings about hospitalizations for pediatric conditions of great public health significance given their notoriety as the leading causes of child death among U.S. children. These high-impact hospitalizations are frequent, comprising 42% of all child hospitalizations in the U.S. in 2006. Majority of hospitalizations were of minor-moderate illness severity, were predominantly within urban hospitals, without significant variation in the overall frequency of hospitalizations by the teaching or children’s hospital status of the treating hospitals. Of importance, however, stepwise increment in levels of patient illness severity was associated with greater likelihood of hospitalization at children’s hospitals, compared with other hospital types. Elevated patient illness severity was also associated with inter-hospital patient transfer, greater likelihood of hospitalization within hospitals located in urban areas, and insurance coverage by the Medicaid program. Differential hospitalization of patients according to their illness severity was highly correlated with concomitant variation in hospital resource use burden.
In aggregate, the frequency of hospitalizations did not vary by the type of hospital, however; a pattern of differential hospitalization was observed according to patient illness severity, with most of the children with heightened illness severity receiving care at children’s hospitals. As previously reported,
 this observation suggests a practice of pre-hospital patient triage according to illness severity, with funneling of the most severely ill patients to children’s hospitals where specialized care might be more readily available. Elevated patient illness severity, which might be a marker of disease progression despite ongoing health care, was also associated with increased likelihood of inter-hospital transfer, most often to a children’s hospital. Hospitalizations involving inter-hospital transfer deserve further investigation given this finding which corroborates prior reports which have described an association between interhospital transfer and both heightened illness severity and elevated hospital resource use
In an era of scarce health care resources and a push for accountable health care, it is important to better understand resource use for these high-impact conditions and how it varies by the type of treating hospital. Such characterization might provide insights into hospital-level variation in health care resource use for pediatric hospitalizations as a whole. This study revealed significant variation in resource use according to both the type of hospital where children received care, and the severity of patient illness. Unsurprisingly, extremely ill children had much longer average hospital stay and higher average hospital charges, when compared with children with lower illness severity. Further, among hospitalizations with either major or extreme illness severity, children’s hospitals and non-children’s teaching hospitals had significantly longer cumulative annual hospital stay (in patient-days) when compared to hospitals without teaching or children’s hospital status, a reflection of higher census of hospitalizations with elevated illness severity at the more specialized hospitals.
Among hospitalizations with lower illness severity, however; there was an opposite observation, as hospitals without teaching or children’s status had the highest number of patient-days compared with other types of hospitals. This is an important finding as it reflects a divergence of hospital resource use by type of hospital, with the more severely ill utilizing more patient-days at more specialized hospitals, while the less specialized hospitals have a higher resource use accruing to less severely ill patients. This finding is novel because, while a previous study among hospitalizations for common pediatric conditions highlighted variation in the duration of hospitalization by hospital type, the authors were unable to attribute the observed variation to any specific factors
. A significant limitation of that study, however, was the inability to describe and account for patient illness severity, an important confounder of the relationship between hospital type and resource use. As reported in the current study, disparate hospital resource use appeared to be highly correlated with patient illness severity. Despite this important finding, however; it is important to note that outside of illness severity, multiple patient characteristics, practice patterns, or institutional factors, may cause wide differences across hospitals in the duration of hospital stay,
 and should be further explored in a systematic fashion to develop efficient health care delivery systems that also enhance patient outcomes.
Cumulative annual hospital charges also varied by hospital type and patient illness severity. Hospitalization of children with high (major or extreme) illness severity within children’s hospitals and non-children’s teaching hospitals accrued higher charges than at hospitals without teaching or children’s hospital status. Although the frequency of hospitalizations for children with low (minor-moderate) illness severity was higher among hospitals without teaching or children’s hospital designation than other hospital types; the pattern of differential charges persisted among this lower illness severity group, with accrual of higher charges at the more specialized hospitals.
It is unknown why hospital charges that accrued to high-impact hospitalizations were higher the more specialized the hospital, regardless of patient illness severity. Various theories have been expounded to explain why children’s and teaching hospitals might accrue more charges than hospitals without teaching or children’s designations. It has been previously speculated that sub-specialty care and use of advanced technology within these latter specialized hospitals might explain some of the differential charges reported
. Higher charges have also been reported to accrue among hospitalizations in teaching versus non-teaching hospitals presumably as a result of specialization of medical care, innovations in care, and medical education.
[16, 17] Future study is warranted to investigate in-hospital resource use and the associated patient- and hospital-level outcomes for children hospitalized with high-impact conditions.
Although commercial insurance plans and the Medicaid program were the principal insurance payers for hospitalizations with high-impact pediatric conditions overall; the Medicaid program bore greater burden of coverage when compared with other insurance payers, with increasing patient severity. Insuring more than half of the extremely ill children and shouldering the burden of increasing numbers of patient as severity of illness worsened; this observation of elevated illness severity among the Medicaid-insured children might be a reflection of the program’s mission to provide coverage for children more likely to be indigent, with comorbid illness, and presumably poor access to the health care system, with resultant high illness severity upon hospitalization
[18, 19]. The finding highlights the safety net nature of the Medicaid program that raises the concern for worse outcomes for children if the existence of this and similar programs was jeopardized
[20, 21]. Further research is warranted to elucidate any modifiable determinants of child health and illness that might contribute to the described characteristics of pediatric high-impact hospitalizations, and variation in hospital resource use.
The study finding of disparate hospitalization of the most severely ill children to children’s hospitals might have implications for health care policy makers. It suggests the critical importance of in-depth assessment of patient illness severity among hospitalized children, and incorporation of such assessment into measures of child health outcomes and hospital resource use. Further, patient severity measures should be included in appropriate risk-adjustment of benchmark measures used for inter-institutional comparison of hospital performance and resource use to ensure that hospitals which care for very severely ill children ab initio, or on inter-hospital transfer, are not penalized for doing so, by policy-makers and insurance payers.
The findings of the current study should be interpreted in light of certain limitations. The KID is a database of administrative discharge data without clinical information beyond what can be captured in ICD-9-CM diagnosis and procedure codes. Hence, it was not possible to study the clinical course for each patient, and how clinical care was coordinated at the patient and hospital levels, within the hospitals. Also, the KID has no follow-up or longitudinal information on patients after hospital discharge. Therefore, determination could not be made of the long term fatal or non-fatal outcomes for survivors of these leading conditions of child mortality in the U.S.