Patients with single ventricle (SV) congenital heart disease (CHD) incur high hospital costs during staged surgical palliation. Health care resource utilization for noncardiac admissions in patients with SV has not been reported. This study sought to compare costs and outcomes for common noncardiac hospital admissions between patients with SV and patients without CHD. Hospital discharge data from the University Health System Consortium from January 2011 to December 2013 was queried for patients aged ≤18 years with International Classification of Diseases, Ninth Revision (ICD-9) codes for SV lesions: hypoplastic left heart syndrome (746.7), tricuspid atresia (746.1), or common ventricle (745.3). Primary diagnosis, direct cost, length of stay (LOS), intensive care unit admission rate and mortality data were obtained. The 10 most common noncardiac admission diagnoses were compared between patients with SV and patients without CHD using t test and Fisher’s exact test. Total direct cost, LOS, and intensive care unit admission rate were higher for patients with SV for all diagnoses with the exception of LOS for dehydration, which was not different between groups. Hospital mortality was significantly higher for patients with SV admitted for acute kidney injury, esophageal reflux, failure to thrive, respiratory syncytial virus bronchiolitis and pneumonia. In conclusion, our study demonstrates that patients with SV CHD admitted with noncardiac diagnoses have higher health care resource utilization compared to those without CHD. As long-term survival increases, it can be expected that this patient group will use a disproportionate amount of medical dollars. Further characterization of costs will be important so steps can be taken to reduce or prevent hospitalization in these patients.
Survival of patients with single ventricle congenital heart disease (SV CHD) has markedly improved since the advent of staged surgical palliation and cardiac transplantation. As a result, the prevalence of subjects living with SV CHD has increased, changing a once fatal disease into a chronic one. Health care costs for patients with CHD are high compared with the general population. As health care costs have increased, an emphasis has been placed on further characterizing resource utilization for patients with CHD in an attempt to better understand the public health impact of the disease. Health care resource utilization (HCRU) has been reported in patients with SV CHD, but data remain sparse. Single-center and multicenter studies have focused on the costs of surgical palliation and hospital admissions related to CHD in both pediatric and adult populations. Recent studies have attempted to further characterize inpatient hospital costs by specific lesions and patient demographics. However, hospitalizations for noncardiac diagnoses are likely to be far more common than procedural admissions, and there are no published data on the resource utilization for hospitalizations for noncardiac diagnoses in patients with SV CHD. The primary aim of this study was to describe the HCRU and outcomes for hospitalizations for common noncardiac diagnoses in pediatric patients with SV CHD in the United States. We hypothesized that resource utilization for noncardiac hospital admissions in pediatric patients with SV CHD would be higher than for children without CHD.
Methods
The University Health System Consortium (UHC) is an alliance of 115 academic medical centers and 165 affiliated hospitals. Their Clinical Data Base/Resource Manager (CDB/RM) is a large administrative database with discharge data from these institutions. After approval from the University of Arizona Institutional Review Board, we performed a retrospective review of deidentified discharge data from inpatient hospitalizations by querying the UHC CDB/RM from January 2011 to December 2013 for patients aged ≤18 years at the time of hospital admission. Neonates (<30 days old) were excluded to minimize the inclusion of admissions for stage 1 palliation/Norwood procedure. Patients with SV were defined as having a primary or secondary admission diagnosis of hypoplastic left heart syndrome (ICD-9 code 746.7), tricuspid atresia (ICD-9 code 746.1), or common ventricle (ICD-9 code 745.3). To exclude admissions for staged surgical palliation, procedure codes associated with any stage of palliative surgery, as previously defined, were excluded. Admissions associated with procedural codes for cardiac catheterizations and electrophysiology procedures were also excluded to further limit the data set to noncardiac encounters. For the comparison group, the UHC CDB/RM was queried for patients without CHD, as defined by the 32nd Bethesda Conference, by excluding the appropriate ICD-9 codes.
Primary diagnosis, age at admission, length of stay (LOS), direct hospital costs, ICU admission rate, mean ICU LOS, and mortality rate were collected. The 10 most common noncardiac admission diagnoses were identified for the patients with SV CHD, and the costs and outcomes were compared between SV CHD and patients without CHD using t tests for continuous variables and chi-square or Fisher’s exact test, as appropriate, for categorical variables.
Results
There were a total of 893,264 admissions for patients without CHD (median age 8.1 years, range 1 month to 18 years) and 2,515 noncardiac admissions for patients with SV CHD (median age 1.8 years, range 1 month to 18 years). Figure 1 shows the distribution of ages for both groups. Non-CHD admissions had a bimodal age distribution, whereas patients with SV CHD were skewed to younger ages.
The 10 most common noncardiac admission diagnoses (and ICD-9 codes) are included in Table 1 . The ICU admission and mortality rates for each diagnosis are presented in Table 1 . ICU admission rates were significantly higher for all diagnoses for patients with SV CHD. With the exception of acute upper respiratory infection, asthma, dehydration, and fever, mortality rates were also higher in patients with SV CHD. Acute kidney injury (AKI) had the highest ICU admission rate and mortality in patients with SV CHD. Fifteen (88%) of the deaths in patients with SV CHD were in children aged <1 year.
| Admission diagnosis (ICD-9 code) | Non-CHD admissions (n = 893,264) | SV CHD admissions (n = 2,515) | p |
|---|---|---|---|
| Acute URI NOS (465.9) | |||
| Admissions | 7,774 (0.9%) | 108 (4%) | <0.001 |
| ICU cases | 10.3% | 31% | <0.001 |
| Mean ICU days | 2.32 | 3.15 | – |
| Mortality | 0% | 1% | 0.06 |
| Acute kidney injury (584.9) | |||
| Admissions | 1,315 (0.2%) | 21 (1%) | <0.001 |
| ICU cases | 24.8% | 70% | <0.001 |
| Mean ICU days | 5.53 | 11.56 | – |
| Mortality | 0.9% | 24% | <0.001 |
| Asthma NOS (493.90) | |||
| Admissions | 1,802 (0.2%) | 21 (1%) | <0.001 |
| ICU cases | 8.5% | 33% | <0.001 |
| Mean ICU days | 1.77 | 6.94 | – |
| Mortality | 0% | 0% | 1.000 |
| Dehydration (276.51) | |||
| Admissions | 12,888 (1.4%) | 72 (3%) | <0.001 |
| ICU cases | 3.7% | 35% | <0.001 |
| Mean ICU days | 2.23 | 1.98 | – |
| Mortality | 0.1% | 0% | 0.855 |
| Esophageal reflux (530.81) | |||
| Admissions | 5,004 (0.6%) | 103 (4%) | <0.001 |
| ICU cases | 13% | 52% | <0.001 |
| Mean ICU days | 4.49 | 8.58 | – |
| Mortality | 0% | 5% | <0.001 |
| Failure to thrive (783.41) | |||
| Admissions | 4,593 (0.5%) | 79 (3%) | <0.001 |
| ICU cases | 4.1% | 40% | <0.001 |
| Mean ICU days | 5.13 | 8.07 | – |
| Mortality | 0% | 3.8% | <0.001 |
| Fever NOS (780.60) | |||
| Admissions | 7,432 (0.8%) | 26 (1%) | 0.27 |
| ICU cases | 4.6% | 28% | <0.001 |
| Mean ICU days | 2.67 | 5.47 | – |
| Mortality | 0.1% | 0% | 1.000 |
| Non-RSV bronchiolitis (466.19) | |||
| Admissions | 13,353 (1.5%) | 51 (2%) | 0.03 |
| ICU cases | 15.2% | 43% | <0.001 |
| Mean ICU days | 3.01 | 7.13 | – |
| Mortality | 0% | 0% | 0.89 |
| Pneumonia organism NOS (486) | |||
| Admissions | 22,978 (2.6%) | 52 (2%) | 0.11 |
| ICU cases | 13.8% | 29% | 0.002 |
| Mean ICU days | 3.36 | 9.23 | – |
| Mortality | 0.2% | 4% | <0.001 |
| RSV bronchiolitis (466.11) | |||
| Admissions | 19,945 (2.2%) | 42 (2%) | 0.06 |
| ICU cases | 19.4% | 50% | <0.001 |
| Mean ICU days | 4.19 | 4.66 | – |
| Mortality | 0.1% | 2% | 0.004 |
Direct costs were greater in patients with SV CHD for all diagnoses ( Figure 2 ). AKI had the highest direct costs for patients with SV CHD, followed by esophageal reflux, and failure to thrive. The diagnoses with the highest direct costs for patients without SV CHD were the same, but these were significantly lower than for patients with SV CHD.
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