Methods

The study was conducted using de-identified patient data from the National Inpatient Sample (NIS) database, a part of the Healthcare Cost and Utilization Project (HCUP), which is compiled by the agency for Health care Research and Quality (AHRQ). The NIS database randomly samples 20 percent of the discharges from participating hospitals in 47 US states and the District of Columbia. It contains data from more than seven million hospital stays each year (8). Data from the years 2000–2017 were used for the purposes of this study. The study was exempt from an institutional board review as the use of data from approved unidentified public data sets is not considered human subject research.
The study population was identified using the International Classification of Disease, Ninth and Tenth Revisions, Clinical Modification (ICD-9&10-CM). Patients were included in the study if they meet the following criteria. In essence, the patient was less than one year of age, had a diagnosis of truncus arteriosus (ICD codes: 745.0 & Q20.0), and had truncus arteriosus repair procedure (ICD-9-PCS: 35.83, 35.92 and corresponding ICD-10 procedure codes) during the index of hospitalization. Patient data queried included demographics and patient clinical characteristics. Patient demographic data collected included: age, sex, race, primary payer, location of the hospital, type of hospital, hospital bed size, the region of the hospital, type of admission (elective or non-elective) and admission day of the week (weekend or weekday). Primary outcomes were identified before the analysis; these included death before hospital discharge, length of stay (LOS), and hospital cost of charge. We compiled a list of common procedures, comorbidities, and complications and evaluated their prevalence in those who died during the hospitalization. For the analysis of outcomes in patients with 22q11.2 deletion syndrome, patients were stratified into two groups: those with and without 22q11.2 deletion syndrome using ICD code 279.11, 758.32, D82.1, and Q93.81. Data were described using median (interquartile range) for continuous variables as deemed appropriate. Categorical variables were described as frequency (percentage). Survivors and Non-survivors were compared with regards to demographic, clinical characteristics, and outcomes using Mann-Whitney U test for continuous characteristics and Chi-square or Fisher’s exact tests for categorical characteristics. Frequency of truncus arteriosus repair, in-hospital mortality, and LOS were evaluated over the years of the study. Trends were assessed for significance using Jonckheere–Terpstra test. P < 0.05 was considered significant. In an effort to minimize bias and to adjust for measurable confounders, a univariate analysis was initially performed to identify potential predictors of in-hospital mortality, thereafter, variables with statistical significance (p < 0.15) were incorporated in a multivariable analysis using a logistic regression model. We used the SPSS software, version 25 (SPSS Inc., Chicago, IL) for all statistical analyses.
Results:
Overall, there were 3009 infants with truncus arteriosus that met the inclusion criteria. The majority of these patients (2026, 67.4%) had their surgical repair at ≤ 28 days of age. There was no predominance of either sex (male 51.2% vs. female 48.8%). The majority of the patients were of the White race (51.6%), followed by the Hispanic race (23.3%). Primary payer insurance was equally divided between Private insurance and Medicaid (46.6% and 46.3%, respectively). The majority of the patients were admitted to large bed-size hospitals (59.9%). Patients discharged from the hospital were equally spread throughout the year with no seasonal variation. The majority of the hospitalizations were non-elective admissions (78.8%). In-hospital mortality was 326 (10.8%). Mortality was stable with a non-significant decrease over the years of the study (Std. J-T statistics -1.063, p = 0.288, Figure 1). Characteristics of survivors versus non-survivors are presented in table 1. Mortality rates were higher in neonates (12.9% vs. 6.4%, p < 0.001). Patients with Black, Native American or Hispanic race had significantly higher mortality than White race (16.5%, 15.6%, 13.5% vs. 7.9%, p < 0.001, respectively) and mortality in patients with Medicaid insurance was significantly higher than those with private insurance (14.4% vs. 8.0%, p < 0.001). Mortality rates during elective admissions was 7.4% versus 10.6% for non-elective admissions (p = 0.020).
Table 2 shows the outcomes of infants with repaired truncus arteriosus. Non-survivors had prolonged median length of stay (non-survivors 29 days [IQR 12–61] vs. survivors 24 days [IQR 14–40], p = 0.009), this was associated with twofold increase in the cost of hospitalization in the non-survivors (non-survivors $522,615 [$253,366–$842,009] vs. survivors $285,114 [$170,681–$526,175], p < 0.001). Of note, 47.4% of the non-survivors were receiving ExtraCorporeal Membrane Oxygenation (ECMO) life support during the hospitalization versus 2.2% of survivors (OR = 39.4, p < 0.001). Prematurity (gestational age < 37 weeks) and low birth weight (weight < 2500g) were associated with increased odds risk of mortality (OR = 1.95, 95% CI: 1.40–2.72, p < 0.001, and OR = 1.39, 95% CI: 0.95–2.03, p = 0.087, respectively). Chromosomal anomalies other than 22q11.2 deletion syndrome were present at a similar frequency in both survivors and non-survivors (survivors 4.7% vs. non-survivors 4.9%, p = 0.782). Surprisingly, 22q11.2 deletion syndrome was present less frequently in non-survivors (non-survivors 20.9% versus survivors 28.0%, p = 0.007). Overall, 22q11.2 deletion syndrome was present in 27.2% of the patients. In table 3, we compiled a list of in-hospital complications and evaluated the association of these complications with in-hospital mortality (table 2). Stroke, acute kidney injury (AKI), pleural effusion, venous thrombosis, intraventricular hemorrhage, and necrotizing enterocolitis were all associated with increased odds risk of mortality (OR = 12.8, 4.37, 1.69, 4.85, 1.73 and 4.89, respectively). Pulmonary hypertension was not associated with an increased odds risk of mortality.
A univariate analysis followed by a multivariable regression analysis was performed to further analyze the dynamics between mortality predictors (tables 3 and 4). The following factors were found to be associated with increased mortality in the multivariate analysis: prematurity (aOR = 2.43, 95% CI: 1.40–4.22, p = 0.002), diagnosis of stroke (aOR = 26.2, 95% CI: 10.1–68.1, p < 0.001), necrotizing enterocolitis (aOR = 3.10, 95% CI: 1.24–7.74, p = 0.015) and presence of venous thrombosis (aOR = 13.5, 95% CI: 6.7–27.2, p < 0.001). Private insurance and 22q11.2 deletion syndrome were associated with lower odds of mortality (aOR = 0.34, 95% CI: 0.20–0.55, p < 0.001, and aOR = 0.54, 95% CI: 0.34–0.87, p = 0.011, respectively). In the multivariate analyses: AKI and pleural effusion were not associated with increased mortality. Patients who received ECMO support or had cardiac catheterization procedure during the hospitalization had increased odds of mortality (aOR = 82.0, 95% CI: 44.5–151.4, p < 0.001, and aOR = 1.65, 95% CI: 0.98–2.77, p = 0.060, respectively). Successful cardiopulmonary resuscitation during the hospitalization was not associated with a significant increase in mortality (aOR = 1.29, 95% CI: 0.54–3.11, P = 0.570).