ELECTRONIC ARTICLE |


* Department of Cardiology, Childrens Hospital, Boston, Massachusetts
Columbia University, Mailman School of Public Health, New York, New York
Cook Childrens Heart Center, Fort Worth, Texas
|| Columbia University, School of Nursing, New York, New York
| ABSTRACT |
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Methods. We examined hospitalizations for infants
30 days of age who were born with HLHS, using hospital discharge data from the 1997 Kids Inpatient Database. To explore treatment choices, clinical outcomes, and resource use, we used International Classification of Diseases, 9th Revision, Clinical Modification diagnostic and procedure codes to classify discharges according to type of surgical intervention versus no surgical intervention. To investigate outcomes in more detail, we identified secondary diagnoses noted at discharge, using International Classification of Diseases, 9th Revision, Clinical Modification codes, and stratified results according to type of surgical intervention.
Results. Of a total of 550 patients with HLHS, 234 underwent the Norwood procedure, 17 underwent orthotopic heart transplantation, and 106 died in the hospital with no reported surgical intervention. Although we found no demographic variables to be significantly associated with the type of treatment received, discharged patients who died without surgical intervention were significantly more likely to have received care in hospitals identified as small (odds ratio [OR]: 1.5; 95% confidence interval [CI]: 1.033.1) or not childrens hospitals (OR: 2.02; 95% CI: 1.133.6). Secondary diagnoses of cardiac arrest (OR: 2.0; 95% CI: 1.13.4) and seizures (OR: 2.6; 95% CI: 1.25.5) occurred more frequently in orthotopic heart transplantation cases than in Norwood procedure cases.
Conclusions. These data from a national perspective reflect outcomes of infants with HLHS during a time when rates of initial survival after surgical intervention were considered to be improved. These findings may be useful to clinicians when they are considering and recommending initial medical and surgical strategies currently being proposed for the treatment of HLHS.
Key Words: hypoplastic left heart syndrome congenital heart disease infants Kids Inpatient Database clinical outcomes secondary diagnoses resource use
Abbreviations: HLHS, hypoplastic left heart syndrome KID, Kids Inpatient Database ICD-9-CM, International Classification of Diseases, 9th Revision, Clinical Modification OHT, orthotopic heart transplantation LOS, length of stay THC, total hospital charges OR, odds ratio CI, confidence interval
Hypoplastic left heart syndrome (HLHS) remains one of the most complex congenital heart defects to treat, both medically and surgically. Despite advances in treatment, HLHS continues to have the highest mortality rate, of all congenital heart defects, for infants <1 year of age.1 HLHS is a combination of congenital cardiac anomalies involving hypoplasia of the ascending aorta, aortic valve atresia or stenosis, a small or absent left ventricle, and mitral atresia or hypoplasia.2 Before 1980, HLHS was considered universally fatal in the newborn period, leaving the health care team with the sole option of providing compassionate care.26 Currently, most infants diagnosed as having HLHS undergo a series of surgical palliations; a small percentage undergo orthotopic heart transplantation (OHT) as an initial surgical approach.718
As the rates of death after surgical intervention for HLHS have decreased, morbidities resulting from both surgical palliation and transplantation have been reported.1921 Neurologic complications have been noted to occur among infants with HLHS not only as a result of the surgical procedure but also during the preoperative and postoperative periods.2224 Researchers20,23,25 have documented seizures, cerebral palsy, attention-deficit disorder, and decreased IQ scores for children with HLHS who have undergone either palliative surgery or OHT. Although most morbidities encountered after surgical intervention are neurologic, renal failure, complete heart block, respiratory failure, and sepsis have also been documented.8,12,2634
Despite decreasing surgical mortality and morbidity rates in the past decade, there is no consensus regarding the best treatment. Physicians and parents must still consider the choice between surgical palliation, OHT, and compassionate care. The purpose of this investigation was to examine, from a national perspective, initial clinical outcomes and secondary diagnoses present at discharge for infants born with HLHS, to facilitate initial discussions of treatment choices between health care providers and parents.
| METHODS |
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Sample Selection
Data were abstracted for all hospital discharges of patients who were
30 days of age at admission and were diagnosed as having HLHS, ie, International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) code 746.7. An assortment of procedure codes were used to identify stage I palliation (also known as the Norwood procedure), ie, cardiopulmonary bypass (code 39.61), surgical creation of an atrial septal defect (code 34.42), incision, excision, or occlusion of the aorta (code 38.14), and systemic to pulmonary shunt (code 39.0), because there is no specific ICD-9-CM procedure code for this intervention. ICD-9-CM code 37.5 was used to identify patients who underwent OHT. To determine the frequency of HLHS discharges of patients
30 days of age at admission for whom no surgical procedure during hospitalization was reported, the data element "disposition at discharge" was used to identify infants who died during hospitalization without undergoing a surgical intervention.
Secondary diagnoses for patients with HLHS who were
30 days of age at admission and who were identified as undergoing the Norwood procedure or OHT were determined by abstracting under the data element "diagnosis." Congenital heart anomalies other than HLHS and other congenital anomalies were excluded as secondary diagnoses, because children with congenital heart disease are commonly affected with other syndromes or malformations.
Statistical Methods
The HLHS discharge population was examined by using demographic data elements (gender, race, insurance status, median income, and geographic location) and hospital characteristics (hospital bed size, hospital ownership, location, teaching status, and childrens hospital status). Descriptive statistics were used to describe the HLHS sample, surgical intervention, clinical outcome, and resource use reported for discharges. Resource use was examined by assessing length of stay (LOS) and total hospital charges (THC) accrued during hospitalization.
2 tests and Fishers exact test were used to examine observed demographic and institutional differences between patients with reported surgical interventions and patients who died in the hospital with no reported surgical intervention. Demographic and hospital variables that were significant at P
.05 were used to construct a multivariate logistic regression model. Odds ratios (ORs) with confidence intervals (CIs) at a level of 95% were generated, with ORs of >1 and CIs not including 1 being considered significant. Fishers exact test was also used to compare the frequency of secondary diagnoses according to the surgical intervention; ORs and 95% CIs were again calculated. All data were weighted by using the data element "discharge weight" and were analyzed by using SAS 8.2 (SAS Institute, Cary, NC) and Sudaan (Research Triangle Institute, Research Triangle Park, NC) statistical software.
| RESULTS |
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30 days of age at admission. We found HLHS patients to have a male/female ratio of 2:1. Race was most frequently reported as white (43%), followed by Hispanic (10%). Race was not reported for 34% of the sample. Although HLHS patients were predominately privately insured (62%), there was no identifiable trend with respect to income. Analysis of hospital characteristics revealed that most HLHS discharges occurred in hospitals that were medium to large (79%), private/not for profit (87%), located in urban areas (98%), and identified as teaching hospitals (74%), as well as a childrens hospital or a hospital with a designated childrens unit (70%) (Table 2).
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2:1. However, mean LOS and THC were similar for the 2 surgical groups of patients who died. HLHS patients who died with no reported surgical intervention were noted to have a median LOS of 4 days (range: 1148 days).
Differences Among Patients With HLHS
We observed significant differences between HLHS patients with a reported surgical intervention (n = 251) and HLHS patients who died in the hospital with no reported surgical intervention (n = 106) with respect to the variables gender, race, median income, and geographic region (Tables 1 and 2). We performed multivariate logistic regression to examine in more detail the relationship of demographic variables for HLHS discharges with surgical intervention versus no surgical intervention. The demographic variables used in the logistic model were gender, race, income, and geographic region. We found no statistical difference between the groups when controlling for these demographic variables.
We examined the hospital profile for HLHS discharges by using the variables hospital bed size, hospital ownership, location/teaching status, and whether or not the facility was designated as a childrens hospital (Table 2).
2 analysis demonstrated all institutional variables to be significant. Using the same variables, we performed multivariate logistic regression analysis to examine in more detail the relationship of hospital differences for HLHS discharges with surgical intervention versus no surgical intervention. Our regression model revealed that HLHS patients who were
30 days of age at admission were more likely to be discharged as dead with no reported surgical intervention in institutions reported as small (reference group: large; P = .02; OR: 1.5; 95% CI: 1.033.1) and institutions not identified as childrens hospitals (reference group: childrens hospitals; P = .001; OR: 2.02; 95% CI: 1.133.6).
Secondary Diagnoses at Discharge
We queried the database for secondary diagnoses for HLHS discharges with either the Norwood procedure or OHT. We also queried the database with the ICD-9-CM diagnostic codes for stroke, seizures, respiratory failure, feeding abnormalities, infection, and renal failure, because these comorbidities have been cited in the literature as postoperative complications for infants with HLHS. Table 4 summarizes secondary diagnoses for HLHS patients
30 days of age with a recorded surgical intervention.
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.05) with Fishers exact test were examined for possible confounding or the presence of effect modification. For HLHS discharges, cardiac arrest (P = .01; adjusted OR: 2.02; 95% CI: 1.13.4) and seizures (P < .0001; adjusted OR: 2.6; 95% CI: 1.25.5) were found to be significant for OHT versus the Norwood procedure. | DISCUSSION |
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We are unsure whether discharges recorded as "died during hospitalization" (n = 106) represent patients who were waiting for surgical intervention or patients who were recommended for compassionate care. We observed the median LOS to be 4 days (range: 1148 days). Jenkins et al38 estimated that 1.7% of infants with HLHS died while waiting for the Norwood procedure and 24% of infants with HLHS died while waiting for OHT. Chang et al39 attempted to quantify the percentage of infants with HLHS from a large database who were discharged with the disposition "died in hospital." The researchers concluded that, of 637 infants who died in the hospital, 617 died as a result of planned compassionate care. The authors speculated that this was supported by the fact that more than one-half of the infants in the series died within an average of 3 days of hospitalization.39 Our findings of a median LOS of 4 days are consistent with that study.
In our study, demographic variables were not found to influence the presence or absence of surgical intervention. However, we found that hospitals characterized as small and those not identified as childrens hospitals were more likely to report HLHS death during hospitalization with no surgical intervention.
We observed that resource use varied according to the surgical intervention. For infants who survived surgery, the LOS and THC for OHT exceeded those for the Norwood procedure by
2:1. However, the mean LOS and THC were similar for the 2 surgical groups of patients who died. Little published information is available on the cost of surgical care, and this should be an area of additional inquiry.
We noted that the secondary diagnoses for patients with HLHS who underwent surgical intervention varied in frequency according to the surgical intervention. Patients with HLHS who underwent OHT, compared with the Norwood procedure, were more likely to experience cardiac arrest and seizures. Our findings of seizures for 20% of the patients with HLHS who underwent OHT were similar to those of Raja et al,40 who cited a 21% occurrence among a cohort of patients with HLHS who were monitored over time. The authors concluded that posttransplant seizures were associated with total cardiopulmonary bypass time and the presence of posttransplant complications.40 Although we found this occurrence to be significant, additional studies are warranted, because of the small size of the OHT group.
Cardiac arrest in 17% of HLHS surgical cases is of interest and is another possible explanation for future developmental and intellectual delays. Previous studies reported that infants with HLHS are at risk for abnormal growth and development because of periods of acidosis, hypoxia, seizures, and use of cardiac bypass during the neonatal period.20,41 For infants with HLHS, any of these diagnoses, depending on severity, could be devastating and greatly disabling, altering normal growth and development.42
Limitations
Although the KID 1997 is considered to provide a representative sample, discharge information originates from only 22 states. The KID did not contain unique patient identifiers or record linkage numbers, making it impossible to identify discharges as individual patients. In an effort to overcome this limitation, we identified an arbitrary age at admission of
30 days, to examine the initial hospitalizations for infants with HLHS. It is not known whether the HLHS discharges recorded as transferred to short-term facilities represent transfers to short-term facilities not included in the database or to other facilities included in the KID (thus being recounted in the total number of discharges with a surgical intervention). For this reason, we examined this sample of HLHS discharges under the assumption that an individual might incur multiple hospitalizations and could have >1 discharge record in the year 1997.
Missing data and coding errors are universal limitations in the use of large administrative databases. This was best indicated by the data element "race," which was reported as missing for 33% of the HLHS sample. We therefore could not conclude with certainty that race was not a factor in treatment choice or clinical outcome.
Compassionate care for this group of infants could not be identified with certainty, because there is no specific ICD-9-CM code available for this treatment option. We attempted to overcome this limitation by restricting the age at admission to
30 days, to identify the initial treatment and hospitalization period and to examine patients who died during hospitalization with no reported surgical intervention. It is also of note that some infants with HLHS might have been excluded from this database as a result of not being diagnosed during newborn admission and dying at home or possibly being misdiagnosed as experiencing sudden infant death syndrome.
At the beginning of our study, a limitation that was foreseen was the lack of clinical data, which is another limitation of all studies using administrative databases in outcomes research.43 In this population, birth weight and organ function have been cited as predictors of initial clinical outcomes, as well as long-term growth and development.44 Additional explanations of the severity of secondary diagnoses would have been useful for determination of the long-term health care services required. Conclusions regarding observed differences between surgical interventions according to secondary diagnoses should be investigated in more detail, because of the small sample of patients with HLHS who underwent OHT. This database was available only for the year 1997, limiting our ability to study trends in clinical outcomes and resource utilization with time. Additional studies should examine direct and indirect costs of care with time.
Implications
Although survival rates for infants after surgical intervention have improved in the past 20 years, there is still a great possibility that these infants will be at risk for residual mental and physical abnormalities. The initial consultations between health care providers and parents at the time of HLHS diagnosis are extensive, requiring discussion of various treatment options and outcomes, ie, not only survival rates but also descriptions of morbidities associated with treatment. Use of the only currently available national database of hospitalized children with disease allowed our research team to provide an overview of initial clinical outcomes for a relatively large number of patients with a rare and complex congenital heart defect.
| CONCLUSION |
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| FOOTNOTES |
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Reprint requests to (J.A.C.) Department of Cardiology, Childrens Hospital, 300 Longwood Ave, Boston, MA 02115. E-mail: jean.connor{at}cardio.chboston.org
| REFERENCES |
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