Table 1 provides summary statistics for inpatient admissions, costs and LOS among adolescents and young adults with CHDs by selected characteristics for 2009–2013, overall and stratified by CHD severity. We identified 5,100 unique individuals with 9,593 corresponding admissions (6,889 admissions (72%) had a documented CHD) during the study period. Of all individuals, 1,780 (35%) had more than one admission during the study period, totaling 6,273 admissions. Median (IQR) charges and costs per admission, respectively, were $26,111 ($45,403) and $10,307 ($17,486) overall. Median (IQR) and mean (SD) LOS were 3.0 (4.0) and 5.7 (10.6) days per admission, respectively.
Median inpatient costs increased with decreasing age and were higher among males ($12,402) than females ($8,793). Although the majority of inpatient admissions were among females (53.9%), 22% were pregnancy-related. Private insurance was listed as the primary payer type for most admissions (65.1%), but costs were the highest for Medicare admissions (median cost: $11,888) compared to other primary payers listed (median costs range: $6,741 to $10,844). Higher median inpatient admissions costs were seen with cardiac/vascular hospitalizations ($16,141) compared to non-cardiac/non-vascular ($7,777), and for surgical hospitalizations ($20,626) compared to medical ($6,861).
Emergency visits comprised 55.1% of admissions and elective hospitalizations had the highest median cost ($15,614). Emergency department service was received in almost half of inpatient admissions among individuals with a CHD diagnosis; however, inpatient admissions without emergency department services ($13,507) incurred higher median costs than those with emergency department services ($7,825).
Overall hospitalization costs were higher among those with severe CHDs ($12,993) compared to non-severe CHDs ($9,845), but cost trends were similar across individual and inpatient admission characteristics for those with severe and non-severe defects. Inpatient admissions for individuals with severe defects comprised 17.1% of all admissions among our population. Compared to individuals with non-severe CHD, individuals with severe CHD had a lower proportion of admissions among individuals in the 20–30 year old age group (49.2% vs 62.0%) and with emergency department service (44.6% vs 49.6%), and a higher proportion of admissions categorized as cardiac/vascular (52.7% vs 36.7%) and in NYC (66.2% vs 52.6%).
Figure 1 displays total inpatient admissions and costs for each year from 2009 to 2013. Total admissions increased 48.7% from 1,538 in 2009 to 2,287 in 2013, while total inpatient costs increased 111.2%, from $24.7 million in 2009 to $52.2 million in 2013. Among individuals with severe CHDs, inpatient admissions increased 22.5% from 2009 to 2013, while total inpatient costs increased 101.5% from $5.7 million in 2009 to $11.5 million in 2013. Among individuals with non-severe CHDs, inpatient admissions increased 54.8%, from 1,249 in 2009 to 1,933 in 2013, and total inpatient costs increased 114.1% from $19.0 million in 2009 to $40.8 million in 2013. Areas with larger proportions of inpatient admissions generally had higher total inpatient costs (Figure 2). The NYC HSA accounted for 54.9% of inpatient admissions and 67.5% of the inpatient costs.
Table 2 shows the top cardiac/vascular and non-cardiac/non-vascular primary reasons for hospitalization, for inpatient admissions, excluding pregnancy-related admissions, ranked by the number of inpatient admissions and by median inpatient costs among those with 10 or more admissions. The top three cardiac/vascular reasons by number of admissions were “Cardiac Valve Procedures without Cardiac Catheterization" (n = 479), “Percutaneous Cardiovascular Procedures without Acute Myocardial Infarction” (n = 441), and “Other Cardiothoracic Procedures” (n = 370). The top three cardiac/vascular reasons by median inpatient cost were “Heart and/or Lung Transplant” ($291,932), “Tracheostomy with Mechanical Ventilation 96+ Hours with Extensive Procedure or Extracorporeal Membrane Oxygenation” ($222,168), and “Cardiac Defibrillator and Heart Assist Implant” ($43,251).
After excluding pregnancy-related admissions, the top three non-cardiac/non-vascular primary reasons for hospitalization by number of admissions were “Seizure” (n = 188), “Other Pneumonia” (n = 178), and “Septicemia and Disseminated Infections” (n = 147). The top three non-cardiac/non-vascular reasons by median inpatient costs, among those with 10 or more admissions, were “Tracheostomy with Mechanical Ventilation 96+ Hours without Extensive Procedure” ($108,323), “Dorsal and Lumbar Fusion Procedure For Curvature Of Back” ($56,610) and “Extensive Procedure Unrelated To Principal Diagnosis” ($50,046).
Overall, inpatient cost distributions were right-skewed, and inpatient costs for cardiac/vascular admissions were higher than the costs for non-cardiac/non-vascular admissions (Figure 3). For both cardiac/vascular and non-cardiac/non-vascular admissions, inpatient costs for surgical admissions were higher than for medical admissions, with that difference greater for cardiac/vascular admissions than for non-cardiac/non-vascular admissions.
The GEE model constructed to estimate inpatient cost per admission had an overall marginal R2 of 59.6%. The variables with the greatest contributions to the cost prediction model included LOS (71.1% of R2), SOI (15.6% of R2), and medical/surgical classification (6.3% of R2) (Table 3). In the model predicting inpatient cost per day, the overall marginal R2 was 29.2% and the variables with the greatest contributions to cost prediction were medical/surgical classification (36.7% of R2), cardiac/vascular classification (20.0% of R2) and type of admission (14.1% of R2). The average increase of inpatient cost per admission for every additional one day in LOS was $2,543. Males had higher inpatient cost per day compared to females. Individuals with the severe and shunt + valve CHD severity categories had higher inpatient costs per admission than individuals in the other categories. However, individuals with severe CHDs had higher inpatient costs per day than individual in any other CHD severity category. Medicaid as primary payer was significantly associated with lower inpatient cost (per admission and per day). Inpatient admissions with cardiac/vascular or surgical classifications resulted in higher inpatient cost (per hospitalization and per day). Inpatient admissions with extreme SOI incurred higher inpatient cost per admission, while admissions with minor or moderate SOI resulted in higher inpatient cost per day. Additionally, elective or other admissions resulted in higher inpatient cost per day.
After stratifying models by CHD severity and age at encounter, the variables with the greatest contributions to cost per admission prediction models were SOI, LOS, and medical/surgical classification (Table 3). The contribution of LOS to cost prediction was greater in individuals with severe CHDs (80.2% of R2) than in individuals with non-severe CHDs (66.7%). The cost prediction contribution of medical/surgical classification was greater in non-severe CHD individuals (8.3% of R2) than in severe CHD individuals (4.0% of R2) and among 20–30-year-olds (10.1% of R2) compared to 11–19-year-olds (4.3% of R2). The average increases of inpatient cost per admission for every additional one day in LOS were $1,974 and $4,669 in individuals with non-severe CHDs and severe CHDs and $3,146 and $1,866 in individuals aged 11–19 and 20–30 years. Primary payer type with highest cost per admission was private in individuals with non-severe CHDs and other in individuals with severe CHDs. For both age groups, primary payer types of Medicare, self-pay, or other, compared to Medicaid, were all associated with lower inpatient cost per admission. Cardiac/vascular primary reason for hospitalization and extreme SOI were commonly associated with higher inpatient cost per admission in all stratified models. Inpatient admissions classified as surgical and in NYC incurred higher inpatient cost per admission for both non-severe and severe CHDs. Admissions in Northeastern NY had the highest inpatient costs for both 11–19 year-olds and 20–30 year-olds.