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Congenital heart disease
Original research
Patterns in hospital admissions for adults with congenital heart disease for non-cardiac procedures
  1. Jan Oliver Friess1,
  2. Urbano L França1,
  3. Anne Marie Valente2,
  4. James A DiNardo1,
  5. Michael L McManus1 and
  6. Viviane G Nasr1
  1. 1Department of Anesthesiology Critical Care and Pain Medicine, Boston Children's Hospital, Boston, Massachusetts, USA
  2. 2Cardiology, Boston Children's Hospital, Boston, Massachusetts, USA
  1. Correspondence to Dr Viviane G Nasr; viviane.nasr{at}childrens.harvard.edu

Abstract

Objective Advances in management of congenital heart disease (CHD) have led to an increasing population of adults with CHD, many of whom require non-cardiac procedures. The objectives of this study were to describe the characteristics of these patients, their distribution among different hospital categories and the characteristics determining this distribution, and mortality rates following noncardiac procedures.

Methods We retrospectively analysed 27 state inpatient databases. Encounters with CHD and non-cardiac procedures were included. The location of care was classified into two categories: hospitals with and without cardiac surgical programmes. Variables included were demographics, comorbidity index, mortality. Multivariable logistic regression was used to explore predictors for care in different locations.

Results The cohort consisted of 12 944 encounters in 1206 hospitals. Most patients were cared for in hospitals with a cardiac surgical programme (78.1%). Patients presenting to hospitals with a cardiac surgical programme presented with higher comorbidity index (6 (IQR: 0–19) vs 2 (IQR: −3–14), p<0.001) than patients presenting to hospitals without a cardiac surgical programme. Mortality was higher in hospitals with cardiac surgical programmes compared with hospitals without cardiac surgical programmes (4.0% vs 2.3%, p<0.001). Factors associated with provision of care at a hospital with a cardiac surgical programme were comorbidity index (>7: OR 2.01 (95% CI 1.83 to 2.21), p<0.001; 2–7: OR 1.59 (95% CI 1.41 to 1.79), p<0.001) and age (18–44 years: OR 1.43 (95% CI 1.26 to 1.62), p<0.001; 45–64 years: OR 1.21 (95% CI 1.08 to 1.34), p<0.001).

Conclusion Adults with CHD undergoing non-cardiac procedures are mainly cared for in hospitals with a cardiac surgical programme and have greater comorbidities and higher mortality than those in centres without cardiac surgical programmes. Risk stratification and locoregional accessibility need further assessment to fully understand admission patterns.

  • CONGENITAL HEART DISEASE
  • Heart Defects, Congenital
  • Outcome Assessment, Health Care

Data availability statement

Data are available upon reasonable request. The data analysed in this study are available upon reasonable request from the corresponding author and following approval by the Center for Healthcare Information and Analysis of the Commonwealth of Massachusetts, Texas Healthcare Information Collection, the Agency for Healthcare Research and Quality (AHRQ) and the Health Care Cost and Utilization Project (HCUP).

http://creativecommons.org/licenses/by-nc/4.0/

This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/.

http://dx.doi.org/10.1136/openhrt-2023-002410

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    WHAT IS ALREADY KNOWN ON THIS TOPIC

    • Advances in management of congenital heart disease (CHD) have led to an increasing population of adults with CHD, many of whom require non-cardiac procedures. However, the type of hospital to which these patients are referred for their non-cardiac procedures has not been well delineated.

    WHAT THIS STUDY ADDS

    • The majority of adult patients with CHD undergo non-cardiac procedures at hospitals with a cardiac surgical program, particularly when a higher burden of comorbidities is present. Travel distances for adult patients with CHD to these hospitals are longer than to hospitals without cardiac surgical programmes.

    HOW THIS STUDY MIGHT AFFECT RESEARCH, PRACTICE OR POLICY

    • Adult patients with CHD undergoing non-cardiac procedures have a higher periprocedural risk. While most adults with CHD undergo non-cardiac procedures at hospitals that offer cardiac surgery, a considerable number of adult patients is treated at hospitals without a cardiac surgical programme. Future analysis is needed to further understand risk stratification, outcomes and locoregional accessibility to specialised care for this growing patient population.

    Introduction

    Congenital heart disease (CHD) has an incidence of approximately 1% of all live births.1–3 Continuous advances in medical and surgical care of patients with CHD led to a markedly improved survival through and beyond childhood.4 5 Patients with CHD, even those with complex congenital lesions, now typically survive to adulthood. Due to the unchanged incidence of CHD, this dynamic has created a population of adults with CHD that now outnumber the population of children with CHD.6 As the adult CHD population ages the need for non-cardiac diagnostic, interventional and surgical procedures to manage comorbidities related both to ageing and underlying CHD have increased.6

    Perioperative morbidity and mortality are increased in adult patients with CHD undergoing non-cardiac procedures that require anaesthesia, compared with the general population; therefore, it is important to delineate the contributing factors.7 8 There is a paucity of data delineating what proportion of adult CHD patients receive care in hospitals with and without cardiac surgical programmes and the associated travel distances.7

    Using all-encounter data sets from state and federal sources, our intent was to describe (1) the characteristics of adult patients with CHD undergoing non-cardiac diagnostic and therapeutic procedures requiring inpatient admission, (2) the distribution of these procedures between hospitals with and without a dedicated cardiac surgical programme and the travel distances to these hospitals, (3) the factors that determine the distribution of patients in each type of hospital and (4) the mortality rate following noncardiac procedures.

    Methods

    This study is a retrospective cohort analysis of publicly available data from state hospital admission databases. The Institutional Review Board at Boston Children’s Hospital approved the study (Boston, Massachusetts, USA, IRB-P00037078).

    Data source

    Data were obtained directly from the Center for Healthcare Information and Analysis of the Commonwealth of Massachusetts, Texas Healthcare Information Collection and of State-Inpatient Databases (SID) obtained from the Agency for Healthcare Research and Quality (AHRQ) and the Health Care Cost and Utilization Project (HCUP).9–11 These are administrative, all-payer, inpatient care databases comprised of encounter-level information reported by all hospitals to their respective states. Each data set contain clinical and resource-use information that is included in a typical discharge abstract, and over 100 clinical and non-clinical variables included in a hospital discharge summary. These include primary and secondary diagnoses and procedures (using International Classification of Diseases, 10th Revision (ICD-10)), admission and discharge status, patient demographic characteristics (eg, sex, age and race), expected payment source, total charges and length of hospital stay. Data for 2017 or 2018 from 27 states (Arkansas, Arizona, Colorado, District of Columbia, Delaware, Florida, Georgia, Iowa, Kentucky, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, New Jersey, New Mexico, New York, North Carolina, Nevada, Oregon, Rhode Island, Texas, Utah, Vermont, Washington and Wisconsin) were gathered. Since not all data elements are included in every SID, the states of Arkansas, Colorado, District of Columbia, Georgia, Maryland, Maine, Michigan, New Mexico and Nevada were excluded from the distance analysis for the absence of either the Zone Improvement Plan (ZIP) Code or hospital location data.

    Study population

    The study population contained all encounters with patients 18 years or older, which have the diagnosis of CHD and were admitted to a hospital for a non-cardiac diagnostic or therapeutic procedure in an operating room setting. The CHD diagnoses were determined by using ICD-10-CM codes and classified as simple CHD, Single Ventricle Disease or other complex CHD12 13 (online supplemental file 1). The comorbidities were summarised utilising the Elixhauser index. The Elixhauser index is calculated from individual administrative encounter-related ICD diagnoses to provide a measure of the impact of comorbidities on in-hospital mortality.14 15 Procedures were identified by utilising the Medicare Severity-Diagnosis-Related Group system, which indicates procedures that were performed in the operating room.16 All cardiac procedures and procedures related to obstetric care were excluded.13

    Study hospitals

    All hospitals in the databases from the respective states as described above were included in the analysis. Whether hospitals had a cardiac surgical programme was determined by ICD-10 procedure codes for adult and paediatric cardiac surgical procedures. Hospitals that only accounted for less than 10 cardiac surgical procedures per year were not considered hospitals with a cardiac surgical programme.

    Four types of hospitals were identified: paediatric hospitals with a cardiac surgical programme, hospitals with a combined paediatric and adult surgical programme, hospitals with an adult cardiac surgical programme and hospitals without cardiac surgical programme. Due to limited numbers of encounters for adult patients with CHD undergoing non-cardiac procedures at paediatric hospitals, these hospitals were excluded from further analysis. Hospitals with a paediatric and adult cardiac surgical programme were merged to one group as hospitals with an adult cardiac surgical programme.

    Variables analysed

    From the data set, we extracted the following outcome variables: age, diagnoses codes, procedure codes, ethnicity, admission type, encounter type, primary payer, mortality/in-hospital death, and zip codes of hospitals and patient place of residence.

    Statistical analysis

    All analyses were performed within Jupyter Notebooks using Python V.3.7 and open-source data science tools. We report descriptive statistics for admission demographics and characteristics. Patient demographics with normal distributions are summarised by their means and SD, whereas non-normally distributed data are summarised by their medians and IQR. The centroids of the five-digit ZIP codes for each admission were used for mapping and analysis of the distance between patient and hospital when both zip code and hospital geolocation were available.17 18 Distances were calculated using the Haversine formula. Comparisons among hospitals with and without cardiac surgical programme were assessed using the Mann-Whitney U test for continuous variables and the χ2 test for categorical variables. Univariable logistic-regression analyses were performed to evaluate the effects of age, cardiac disease, Elixhauser index, payer and type of procedure on the odds of admission to a hospital with cardiac surgical programme. Multivariable logistic-regression analysis without interactions was performed using significant variables from the univariable analysis to estimate the independent association between age, cardiac disease, Elixhauser index and payer with location of care at a hospital with a cardiac programme. ORs, adjusted OR and 95% CI were calculated. P values were tailed and statistical significance set at p<0.05

    Data availability statement

    The data analysed in this study are available on reasonable request from the corresponding author and following approval by the Center for Healthcare Information and Analysis of the Commonwealth of Massachusetts, Texas Healthcare Information Collection, AHRQ-HCUP.

    Results

    A total of 12 944 encounters in patients older than 18 years and with a diagnosis of CHD were included in the study population (0.073% of the total SID population). There were 23 994 procedures performed in 1206 hospitals (table 1). Of these hospitals, 521 (43%) had a cardiac surgical programme (table 2). Most encounters occurred at hospitals with a cardiac surgical programme (10 107; 78%) and consequently most procedures were also performed in these hospitals (18 886; 78%). Since only 161 procedures in adult CHD patients were performed at paediatric hospitals, these encounters were excluded from further analyses. Overall, the median Elixhauser comorbidity index was 6 (IQR: 0–18). Patients treated at a hospital with a cardiac surgical programme had more comorbidities (4 (IQR: 2–5) vs 3 (IQR: 2–5), p<0.001) and a higher Elixhauser comorbidity index (6 (IQR: 0–19) vs 2 (IQR: −3–14), p<0.001). Hospitals with a cardiac surgical programme had proportionally more encounters with an Elixhauser index above 7, whereas hospitals without a cardiac surgical programme had a higher proportion of encounters with an index of less than 2 (p<0.001, figure 1).

    Figure 1
    Figure 1

    Distribution of patients among hospitals without and with cardiac surgical programme based on congenital heart disease severity and Elixhauser comorbidity score. (A): Distribution of patients with simple complex or single ventricular congenital heart disease lesion. (B): Distribution of patients with Elixhauser comorbidity score in categories score<2, 2–7 and>7. CHD, congenital heart disease.

    View this table:
    Table 1

    Baseline characteristics of admissions

    View this table:
    Table 2

    Differences between hospitals with and without cardiac surgical programme

    The distribution of adult CHD severity in the overall cohort was simple CHD in 8460 (65.4%), complex CHD in 4412 (34.1%) and single ventricle CHD in 72 (0.6%) encounters. There was no statistical difference in the distributions of CHD severity among the two hospital types (p=0.085, figure 1). However, most encounters of patients with a single ventricle lesion occurred at hospitals with cardiac surgical programme (table 2). The most common CHD diagnoses were atrial septal defects (7784), congenital insufficiency of the aortic valve (1781) and ventricular septal defects (589).

    Primary payer in both hospital types was a public source in most cases, with no differences in payers among the hospital types (p=0.073) (table 2). Emergency encounters were the most common type of admission and were significantly more frequent in hospitals with cardiac surgical programmes (63% vs 55%, p<0.001). As summarised in table 3, the most common primary (admitting) diagnosis was cerebral infarction (1637 encounters) followed by osteoarthritis (1089) and septicaemia (632). The most common procedures are summarised in table 3.

    View this table:
    Table 3

    Admitting and cardiac diagnoses and procedures performed in hospitals with and without cardiac surgical programme

    Multivariable analysis revealed the likelihood of admission to a hospital with a cardiac surgical programme to be significantly associated with increasing Elixhauser comorbidity index and with younger age. Specifically, the OR for admission to a hospital with cardiac surgical programme was 1.59 (95% CI 1.41 to 1.79), p<0.001 for a comorbidity index of 2–7 and 2.01 (95% CI 1.83 to 2.21), p<0.001 for a comorbidity index >7. The OR for admission to a hospital with a cardiac surgical programme was 1.25 (95% CI 1.12 to 1.4), p<0.001 for the 18–44-year-old age group and 1.16 (95% CI 1.05 to 1.27), p=0.002 for the 45–64-year-old age group. The severity of the CHD was not associated with admission to a hospital with a cardiac surgical programme. Detailed results of the univariable and multivariable regression analyses are presented in table 4.

    View this table:
    Table 4

    Univariable and multivariable regression analysis for admission to a hospital with cardiac surgical programme

    Overall, in-hospital mortality was 3.6%. Mortality was 4.6% for patients 65 years or older, 3.3% for patients from 45 to 64 years old, and 2.2% for patients aged 18–44 years. The in-hospital mortality was significantly higher at hospitals with a cardiac surgical programme as compared with hospitals without a programme (4.0% vs 2.3%, p<0.001), and more deaths occurred at hospitals with a cardiac surgical programme (405) as compared with hospitals without cardiac surgical programmes (65).

    Table 5 summarises travel distances. The median distance travelled from the patients’ residence to the hospital where they received care was 12.3 (IQR: 4.9–34.1) miles to a hospital with a cardiac surgical programme and 7.3 (IQR: 3.2–17.4) miles to hospitals without a programme (p<0.001). Travel distances were shorter for both types of hospitals in the case of emergent admissions. Figure 2 shows a comparison of travel patterns for patients travelling to a hospital with and without a cardiac surgical programme.

    Figure 2
    Figure 2

    National travel patterns from home to a hospital for patients undergoing noncardiac procedures. (A): Travel distances to hospitals with a cardiac surgical programme. (B): Travel distances to hospitals without a cardiac surgical programme.

    View this table:
    Table 5

    Distances travelled from the place of residence to hospitals with and without a cardiac surgical programme (in miles)

    Discussion

    In this retrospective analysis, 12 944 admissions for non-cardiac procedures in adult patients with CHD were identified across 1206 hospitals. The majority (78%) of admissions were to hospitals with a cardiac surgical programme. The burden of comorbidities in adult patients with CHD admitted to hospitals with cardiac surgical programmes was higher compared with patients admitted to hospitals without a cardiac surgical programme. Younger patients and those with a higher Elixhauser comorbidity index were more likely to be admitted to a hospital with a cardiac surgical programme.

    These findings are consistent with current recommendations for direction of medically complex adult patients with CHD to specialised centres for their care.7 However, increases in capacity at specialised hospitals caring for these patients and an infrastructure for specialised care may not parallel the growth of the adult patient population with CHD.19 In fact, findings from a study using administrative data on outpatient surgery in adult CHD patients described a substantially lower proportion of adult CHD patients receiving care at centres that provide expertise in adult CHD (26%) than our study.20 This difference is likely related to several factors. The study period (2005–2011) is relatively remote, and the data set likely does not reflect current practice. Their analysis used a more granular definition of specialised adult CHD programmes based on presence of one or more of the following: specialised fellowships in ACHD and/or paediatric cardiology, a defined ACHD cardiology programme, and a surgeon who is a member of the Congenital Heart Surgery Society. Their analysis did not include a measure of CHD severity or an assessment of comorbidities. Most importantly, because the authors investigated outpatient surgical procedures, there are likely major differences between the types of surgery performed and patient population analysed in our study. Outpatient surgery is generally performed for minor procedures in patients without major comorbidities, whereas inpatient admissions for surgery are rarely for minor procedures, are generally performed on patients with a greater comorbidity burden and are more likely to be emergent in nature.

    Admission for noncardiac interventions to a hospital with an adult CHD programme is recommended for symptomatic adult CHD patients.7 Highly specialised care for multiorgan disease, such as CHD, is usually based in hospitals that also provide cardiac surgery and cardiac anaesthesia services among other multidisciplinary treatment teams.7 While the description of CHD derived from administrative databases based on ICD codes captures the initial CHD diagnosis, it does not allow delineation of the palliative procedures performed or the residual cardiac lesion burden. In addition, the nuance of patient physiology at the time of the encounter is not captured by ICD codes. Thus, even though patients at hospitals with and without cardiac surgical programmes may have the same ICD code for a CHD diagnosis, the residual lesion and disease burden may be higher in patients who present at centres with cardiac surgical programme, which most likely also contributes to the higher comorbidity burden and a higher mortality seen in hospitals with a cardiac surgical programme.

    Morbidity and mortality after non-cardiac surgery is higher in adult patients with CHD than in adult patients without CHD and a CHD diagnosis alone is associated with higher perioperative mortality and morbidity when adjusted for type of surgery and comorbidities.8 21 22 In our analysis, mortality was higher in hospitals with a cardiac surgical programme as compared with hospital without a programme (4.0% vs 2.3%, p<0.001). It may appear counterintuitive that adult CHD patients directed to a specialised centre would have higher mortality following non-cardiac surgery than those directed to a non-specialised centre. This is likely explained by the fact that patients directed to hospital with cardiac surgery programmes had significantly more medical comorbidities, as the Elixhauser score is strongly associated with perioperative mortality following non-cardiac procedures.23 It is somewhat surprising that, in our analysis, the distribution of CHD severity was not different between the hospital types. However, our data set does not provide information on possible transfers of patients with severe CHD to a specialised facility following admission to a hospital without a cardiac surgical programme.

    Adult patients with CHD travelled longer distances to hospitals with cardiac surgical programmes for their non-cardiac procedures. This same phenomenon has been reported for paediatric CHD patients undergoing non-cardiac procedures.13 Nevertheless, the total distances reported here were shorter (12.3 miles (4.9–34.1)) than those reported for paediatric patients (25.2 miles (10.3–73.8)). This is likely due to the fact that there are more hospitals with an adult cardiac surgical programme (477) than there are with a paediatric cardiac programme (21 offering paediatric cardiac care and 44 offering adult and paediatric cardiac care).13

    It is encouraging that adult CHD patients of younger age were directed to specialised centres in our analysis. This is consistent with the recommendation that paediatric CHD patients be actively transitioned to specialised adult CHD centres in adolescence or early adulthood.7 This finding does not negate the fact that this transition is and continues to be problematic with many patients lost to follow-up.24

    Limitations

    The SID database is based on ICD codes and thus lacks granular stratification of the severity of CHD. Our sample has a higher proportion of defects defined as simple compared with prior reports. It has been demonstrated that ICD codes are frequently erroneous in detecting and classifying CHD patients.25 In addition, when the classification of complexity is based on initial diagnosis and anatomy, it is unclear whether the cardiac defect was repaired or remained unrepaired, and the patient’s associated residual lesion burden and physiology are indeterminate. Unfortunately, these factors can contribute substantially to morbidity and mortality. Additional limitations inherent to registry studies include selection bias, the potential for inaccurate coding and the fact that individual patients may have presented for multiple encounters. In addition, reporting included in the SID is program-based rather than hospital-based and several small satellite hospitals may report under one larger institutional umbrella. This may prevent identification of satellite hospitals and result in consolidation of their data with that of the parent major hospital. The Adult Congenital Heart Association developed criteria for adult CHD programmes accreditation in 2017.26 Since the data in this study were generated prior to accreditation, the programmes were not categorised based on these criteria; however, this designation may be useful for future studies. Finally, the generalisability of our findings using 27 US states should take into consideration that the patterns of care in the states that are not included might differ.

    Conclusion

    In conclusion, most admissions for non-cardiac procedures in adult CHD patients occur at hospitals with a cardiac surgical programme. These patients have a higher burden of comorbidities, greater mortality and travel longer distances to undergo non-cardiac procedures. Analysis of databases with enhanced granularity will be needed to better understand admission patterns, to develop stratification tools, and to assess local and regional accessibility to specialised care.

    Data availability statement

    Data are available upon reasonable request. The data analysed in this study are available upon reasonable request from the corresponding author and following approval by the Center for Healthcare Information and Analysis of the Commonwealth of Massachusetts, Texas Healthcare Information Collection, the Agency for Healthcare Research and Quality (AHRQ) and the Health Care Cost and Utilization Project (HCUP).

    Ethics statements

    Patient consent for publication

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    Supplementary materials

    • Supplementary Data

      This web only file has been produced by the BMJ Publishing Group from an electronic file supplied by the author(s) and has not been edited for content.

    Footnotes

    • Contributors JOF, ULF, MLM and VGN designed the study. JOF, ULF, AMV, JAD, MLM and VGN analysed and interpreted data. JOF, JAD and VGN wrote the manuscript, and all authors revised it. VGN serves as the overall guarantor responsible for overall content.

    • Funding This study has received funding from the Department of Anesthesiology, Critical Care and Pain Medicine, Boston Children’s Hospital.

    • Map disclaimer The inclusion of any map (including the depiction of any boundaries therein), or of any geographic or locational reference, does not imply the expression of any opinion whatsoever on the part of BMJ concerning the legal status of any country, territory, jurisdiction or area or of its authorities. Any such expression remains solely that of the relevant source and is not endorsed by BMJ. Maps are provided without any warranty of any kind, either express or implied.

    • Competing interests None declared.

    • Provenance and peer review Not commissioned; internally peer reviewed.

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