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Ann Thorac Surg 1997;64:44-48
© 1997 The Society of Thoracic Surgeons

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Original Articles: Cardiovascular

Risk Factors for Higher Cost in Congenital Heart Operations

Divisions of Pediatric Cardiology, Pediatric Cardiac Surgery, and Pediatric Cardiac Anesthesiology and Critical Care Medicine, Department of Nursing Services, and Office of Operations Improvement, Duke University Medical Center, Durham, North Carolina

	Abstract

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
Background. For many congenital heart defects, hospital mortality is no longer a sensitive parameter by which to measure outcome. Although hospital survival rates are now excellent for a wide variety of lesions, many patients require expensive and extensive hospital-based services during the perioperative period to enable their convalescence. These services can substantially increase the cost of care delivery. In today's managed care environment, it would be useful if risk factors for higher cost could be identified preoperatively so that appropriate resources could be made available for the care of these patients. The focus of this retrospective investigation is to determine if risk factors for high cost for repair of congenital heart defects can be identified.

Methods. We assessed financial risk by tracking actual hospital costs (not charges) for 144 patients undergoing repair of atrial septal defect (58 patients), ventricular septal defect (48 patients), atrioventricular canals (14 patients), or tetralogy of Fallot (24 patients) at Duke University Medical Center between July 1, 1992, and September 15, 1995. Furthermore, we were able to identify where the costs occurred within the hospital. Financial risk was defined as a large (>60% of mean costs) standard deviation, which indicated unpredictability and variability in the treatment for a group of patients.

Results. Cost for atrial septal defect repair was predictably consistent (low standard deviation) and was related to hospital length of stay. There were factors, however, for ventricular septal defect, atrioventricular canal, and tetralogy of Fallot repair that are identifiable preoperatively that predict low- and high-risk groups using cost as an outcome parameter. Patients undergoing ventricular septal defect repair who were younger than 6 months of age at the time of repair, who required preoperative hospital stays of longer than 7 days before surgical repair, or who had Down's syndrome had a less predictable cost picture than patients undergoing ventricular septal defect repair who were older than 2 years, who had short (<4 days) preoperative hospitalization, or who did not have Down's syndrome ($48,252 ± $42,539 versus $15,819 ± $7,219; p = 0.008). Patients with atrioventricular canals who had long preoperative hospitalization (>7 days), usually due to pneumonia (respiratory syncytial virus) with preoperative mechanical ventilation had significantly higher cost than patients with atrioventricular canals who underwent elective repair with short preoperative hospitalization ($83,324 ± $60,138 versus $26,904 ± $5,384; p = 0.05). Patients with tetralogy of Fallot had higher costs if they had multiple congenital anomalies, previous palliation (combining costs of both surgical procedures and hospital stays), or severe "tet" spells at the time of presentation for operation compared with patients without these risk factors ($114,202 ± $88,524 versus $22,241 ± $7,071; p = 0.0005). One patient (with tetralogy of Fallot) with multiple congenital anomalies died 42 days after tetralogy of Fallot repair of sepsis after a gastrointestinal operation. Otherwise, hospital mortality was 0% for all groups.

Conclusions. Low mortality and good long-term outcome for surgical correction of congenital heart defects is now commonplace, but can be expensive as some patients with complex problems receive the care necessary to survive. This study demonstrates that it is possible to identify factors preoperatively that predict financial risk. This knowledge may facilitate implementation of risk adjustments for managed care contracting and for strategic resource allocation.

	Introduction

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
See also page 49.

Surgical repair of congenital heart defects in infants and children is being accomplished routinely with low mortality in a large number of excellent centers throughout the country. For many defects, hospital mortality is no longer a sensitive parameter by which to measure outcome. Patients survive, leave the hospital, and in most instances begin achieving a reasonably normal existence. Many of these patients require expensive and extensive hospital-based services during the perioperative period to enable their convalescence. These services can substantially increase the cost of care delivery [1–4]. In today's managed care environment, it would be useful if risk factors for higher cost could be identified preoperatively so that appropriate resources could be made available for the care of these patients [5, 6]. The focus of this retrospective investigation is to determine if risk factors for high cost for repair of congenital heart defects can be identified.

	Material and Methods

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
The records of 144 patients undergoing hospital admission to Duke University Medical Center and surgical correction for selected cardiac defects between July 1992 and September 1995 were reviewed. These dates were chosen because they coincided with implementation of a medical center-wide cost tracking system (Transition I) and encompassed a time frame when all data on these patients' hospitalization were available. Congenital heart defects chosen for this review included those with "predictable" patterns of hospitalization in that they represented what were thought to be relatively "straightforward" problems with which to test the value of this analytic tool. The study group included all patients repaired at Duke Medical Center during the time period of this review who presented with atrial septal defects (ASDs; n = 58), ventricular septal defects (VSDs; n = 48), tetralogy of Fallot (TOF; n = 24), and complete atrioventricular canal defects (AV canal; n = 14). Patients with more than one lesion (eg, VSD and ASD) were classified according to their most severe lesion (such as VSD in the example given). Patients with complex lesions of which an ASD, VSD, AV canal, or TOF defect was only part of the cardiac anomaly (eg, interrupted aortic arch with VSD) were not included in this review.

Transition I is a cost-accounting system that relies on the hospital's internal data to track costs (both direct and indirect) from the smallest product level to the broadest procedure level. Financial analysts and management engineers work closely with front-line personnel to determine and refine standards by which to allocate direct (patient care related) costs within a department and indirect (overhead) cost within the hospital. In the case of direct costs, for example, the cost of each laboratory test can be calculated by a formula that accounts for minutes of technician time, equipment time (as a fraction of equipment maintenance), and individual supply items. In the case of indirect costs, parameters such as square footage, number of full-time employees, and effort percentage are used to distribute overhead expense of administration, housekeeping, interns/residents, and social work. Each individual unit cost is composed of variable direct cost, fixed direct cost, and indirect cost. Variable direct cost varies in relation to patient volume (such as cost of medical supplies or number of necessary laboratory technicians or staff nurses). Fixed direct costs are directly related to patient care and do not fluctuate with patient volume (such as equipment costs or the cost of a nurse manager or laboratory director). At the individual case level, medical record and utilization data are combined with product cost information to produce a "case cost." We then analyzed groups of similar cases, looking at variability in length of stay, utilization, and cost. Grouping costs into functional classifications provided a useful overview and quickly pinpointed areas of concern (eg, high cost and high utilization). Cost groups including room and board (inpatient services), pharmacy, surgery (eg, operating room time, anesthesia, surgical supplies), other supply services (such as transfusion services) radiology, laboratory, cardiovascular services (echocardiography, electrocardiography, cardiac catheterization), physical and occupational therapy, respiratory therapy, and diagnostic and therapeutic services (eg, electroencephalography, dialysis, pulmonary function) were examined in targeting areas where further investigation and a change in practice pattern were warranted. These data represent hospital, nonprofessional costs only. Physician charges were not included.

Data were analyzed in aggregate for each patient group. Various risk factors for higher cost were then selected and tested for each group. Selection of risk factors was based on clinical impressions but tested against all patients in each group to determine consistency of the relationship between each factor and cost. All risk factors represented conditions which are apparent before the operation. Financial risk was defined as a large (>60% of mean costs) standard deviation, which indicated significant variability in the treatment for a group of patients. Risk is related to the outcome variability for an intervention; the greater the variability, the greater the risk. If individual patients cluster closely about the mean value, the intervention or procedure is considered low risk. If there is less clustering of costs about the mean, the variability of the intervention is greater and the risk is higher. One way to measure this clustering tendency is to calculate a probability-weighted average of the deviations of possible outcomes from the mean [7]. Having defined risk in this general way, we estimated the amount of risk from a cost perspective by calculating the standard deviation. Differences between groups were tested for statistical significance using Student's unpaired t test. A p value of 0.05 or less was considered to be statistically significant.

	Results

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
One patient (with TOF) with multiple congenital anomalies died 42 days after TOF repair of sepsis after a gastrointestinal operation. Otherwise, hospital mortality was 0% for all groups. Total average cost for each group (with standard deviation) is as follows:

Figure 1 displays cost breakdowns for the various groups in relation to the different components of cost. These data include both direct and indirect costs. It can be appreciated that the higher cost patients show a relatively higher cost in "inpatient services" (room and board) as well as for pharmacy, respiratory care services, and laboratory services. The operating room costs are relatively similar between groups. Figure 2 demonstrates total cost data with standard deviation for selected patient groups. This depiction is used because large standard deviations (greater than 60% of the cost) are readily apparent. In cases where the standard deviation is high, patients can be expected to produce an unpredictable and variable cost pattern and this constitutes a group with high financial risk. Figure 3 graphically illustrates the difference between certain risk groups of VSD patients.

View larger version (57K): [in this window] [in a new window]   Fig 1. . Cost (in dollars; on the ordinate) for various cost allocation categories (abscissa). Data includes both direct and indirect cost and enables comparison between groups for each category. (ASD = atrial septal defect; AV = atrioventricular; CARD SVC = cardiologic services; DIAG SVC = diagnostic services; EMERG & TRANS = emergency and transport; HOSP LAB = hospital laboratory; INPAT = inpatient; ORG ACQ = organ acquisition; OTH = other; PHARM = pharmacy; PHYS THER = physical therapy; RAD SVC = radiologic services; RESP = respiratory; SURG SVC = surgical services; TOF = tetralogy of Fallot; VSD = ventricular septal defect.)

View larger version (24K): [in this window] [in a new window]   Fig 2. . Mean total cost bars and the line of standard deviation are shown for several representative groups. Standard deviation of more than 60% mean total cost defines a group with high (financial) risk. (ASD = atrial septal defect; AV = atrioventricular; LOS = length of stay; TOF = tetralogy of Fallot; VSD = ventricular septal defect.)

View larger version (29K): [in this window] [in a new window]   Fig 3. . Mean total cost bars for groups of patients undergoing ventricular septal defect closure. This graph emphasizes the fact that the cost of ventricular septal defect closure can vary depending on factors that are identifiable preoperatively (length of stay [LOS] < 4 days versus LOS > 7 days, p = 0.008; age < 6 months versus Age > 2 years, p = 0.008; Down's syndrome versus no Down's syndrome, p = 0.05). (S.D. = standard deviation.)

• VSD Cost Risk Factors
  
• Multiple congenital anomalies: $164,802
  
• Preoperative length of stay greater than 7 days: $65,000 versus $27,000
  
• Age:
  
• Less than 6 months: $48,000
  
• Greater than 2 years $15,500 + low standard deviation
  
• Down's syndrome: $49,000 versus $30,000
  Similarly, longer preoperative hospitalization and the need for preoperative mechanical ventilation predicted higher and more variable costs in AV canal patients:
  
• AV Canal Cost Risk Factors
  Preoperative length of stay greater than 7 days
  Preoperative mechanical ventilation/respiratory syncytial virus pneumonia
  High risk versus low risk: $82,324 versus $26,904
  Infants with TOF can be expected to produce higher and more variable cost if they have multiple (noncardiac) congenital anomalies; TOF with pulmonary atresia; severe, unrelenting hypercyanotic spells at the time they present for surgical treatment; or previous palliation (combining cost and care requirements for both procedures):
  
• TOF Cost Risk Factors
  
• Multiple congenital anomalies: $318,463
  
• TOF + pulmonary atresia
  
• Severe unrelenting TOF spells before repair
  
• Two-stage versus one-stage: $79,795 versus $31,710
  
• High risk versus low risk: $175,760 versus $39,512
  

	Comment

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
Low mortality and good long-term outcome for surgical correction of congenital heart defects is now commonplace, but can be expensive for some patients with complex problems. Our investigation tracked the cost incurred by the hospital for the care of selected groups of patients undergoing heart operations for congenital defects.

Patients with ASDs represent a group at low financial risk because the cost is low and uniform from patient to patient. This was expected and was one of the reasons that this group was selected: it provides a "control" with which to test our method of data analysis. The information provided in Figure 2 shows that repair of ASDs can be accomplished at a low and predictable mean cost with little risk of having an individual patient generate a hospital cost that varies significantly from the remainder of the group of ASD patients. "Systems improvement" (eg, fewer hospital days until discharge, fewer laboratory studies) may further lower the total cost, but ASD patients should always represent a low (financial) risk group [8].

Patients with a VSD present a more complex picture. Figure 2 shows that if the entire population of VSD patients is combined, the standard deviation is high, signifying that (unlike the patients with an ASD) financial risk for patients with VSDs is not uniform. Examination of Figure 1 shows that most of this variability is in inpatient services: some patients with VSDs have a prolonged convalescence requiring extended hospital stay. Other patients with VSDs incur a much shorter hospital stay and can be repaired at low cost. Clearly, it would be useful to be able to distinguish these groups preoperatively. We looked at several factors that we believed had an impact on convalescence in our medical center. Patient age, the presence of prolonged preoperative hospitalization, and the presence of Down's syndrome were all associated with a predictably higher cost (see Figs 2, 3). Infants with a large VSD are often extremely ill. Future growth and development (and even survival) may depend on early (first 6 months of life) surgical closure of the defect. The fact that many of these patients are critically ill influences convalescence, and therefore total cost and cost variability. Figure 2 also shows that patients who were hospitalized for more than 7 days before surgical closure of a VSD had a significantly higher mean cost those who were operated on within 4 days of hospital admission. However, length of preoperative hospitalization did not significantly alter financial risk for these patients, because both groups had high standard deviation for cost. Those patients hospitalized for more than a week before VSD closure were more likely to be in severe congestive heart failure or to have a secondary illness associated with the VSD compared with patients hospitalized for 4 days or less before repair (the majority of whom were undergoing elective repair). Financial risk as well as mean total cost might be low for patients who are admitted to the hospital on the same day as the operation (current practice for elective cases), but might also be related to age and the presence of Down's syndrome. Although all VSD patients in this series survived their operation and were discharged home, some generated considerably more cost during their convalescence. The group of patients who were older than 2 years (mostly elective VSD closure) had a cost risk footprint similar to patients with ASDs (see Fig 2) (low standard deviation and low total cost).

It is also possible to define groups with high and low financial risk among patients undergoing repair for AV canal defects or TOF. The patients with AV canal who carried a higher financial risk were those with long (>7 days) preoperative hospitalization, which includes those who were on a ventilator at the time of the operation (see Fig 2). Two patients in this "high-risk" group had respiratory syncytial virus pneumonia at the time of the operation and were operated on because of deteriorating clinical status. Young age (<5 months old) or the presence of Down's syndrome (common in AV canal patients) did not appear to influence the risk for higher cost.

The patients with TOF who were a high financial risk were those with multiple congenital anomalies, those with a long preoperative hospitalization (>7 days) (see Fig 2), those with TOF with pulmonary atresia (versus simple TOF undergoing primary one-stage repair), and patients who presented for repair with severe, unrelenting hypercyanotic spells. Investigation by our group, which is reported separately, demonstrates that two-stage repair of TOF (initial palliation followed by subsequent elective repair) is significantly more costly than elective, one-stage, primary repair in infancy and offers no benefit (and possibly a slight disadvantage) with respect to outcome [9, 10].

These data can be scrutinized in two different and very important ways. The first is the total institutional cost for each procedure. It is important to emphasize that the figures provided represent actual cost (not charges) at Duke University Medical Center during the time frame of this review. They can provide an indirect measure of service delivery with regard to factors that can be adjusted to lower these costs. During the time frame in which the patients in this study received care, our institution had no "care maps" or "critical pathways" in place to guide the care process. The data from this investigation has provided our own group with important data for "systems improvement," and there has been measureable reduction in cost without decrement in quality of outcome for some groups of patients. However, this analysis is not the focus of this article and is mentioned only because it is an observation that attracts initial attention and immediately stimulates speculation and suggestions for lowering costs. The second, and most intriguing, level of data analysis surrounds the concept of cost as an outcome parameter for which risk factors can be described.

As our data clearly demonstrate, not all VSD, AV canal, or TOF patients are the same from the standpoint of financial risk. It is possible to identify factors, before the operation, that predispose some patients to higher cost, and these are summarized in the lists in the Results section. Review of this information as well as the data in Figure 2 would lead us to believe that all ASD closures, VSD closures in patients older than 2 years of age, and elective AV canal repairs can be performed with the likelihood of low risk for generating high or unexpected costs. Otherwise, it is strikingly apparent that the repair of commonplace congenital heart defects can be associated with considerable variability of cost and this defines congenital heart surgery as a risky (from a cost perspective) undertaking. This is a risk that must, of necessity, be shared by the clinical services, the hospital administration, and, most importantly, the patients and their payor sources.

Despite all attempts to reliably predict financial risk, there will still be the occasional patient with a seemingly straightforward problem who will encounter unexpected complications and who will require additional services, which will translate into increased cost. Nevertheless, the data presented in this review provide information that might help us, our administrative "financial stakeholders," and the managed care payors better understand the reality of the financial burden the care for these patients can create. This analysis can be extended to other types of patients, including noncardiac patients, and future prospective work is currently underway to test this ability to predict financial risk in patients (such as those presented in this review) preoperatively. Although this work is more difficult for the clinician to embrace (compared with the challenges of obtaining good surgical outcomes in complex and challenging patients), it may be very important for our future. It may be as important for us to be able to understand and relate these financial risks to the payor groups and risk sharers of our endeavors, as it is for us to understand and relate the risks for poor outcome to the families and care providers of our patients. Dissemination of this information may help alter practice patterns and may facilitate implementation of risk-adjustments for managed care contracting and for strategic resource allocation.

	Acknowledgments

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

	Footnotes

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
Presented at the Forty-Third Annual Meeting of the Southern Thoracic Surgical Association, Cancun, Mexico, Nov 7–9, 1996.

Address reprint requests to Dr Ungerleider, Duke University Medical Center, Box 3178, Durham, NC 27712 (e-mail: unger{at}002mc.duke.edu).

	References

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 

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5. Dudley RA, Harrell FE Jr, Smith LR, et al. Comparison of analytic models for estimating the effect of clinical factors on the cost of coronary artery bypass graft surgery. J Clin Epidemiol 1993;46:261–71.[Medline]
6. Lahey SJ, Borlase BC, Lavin PT, Levitsky S. Preoperative risk factors that predict hospital length of stay in coronary artery bypass patients: 60 years old. Circulation 1992;86(Suppl 1):1181–5.
7. Higgins RC. Analysis for financial management. Homewood, IL: R.D. Irwin, Inc, 1989:244.
8. Davis JT, Allen HD, Cohen DM. Fiscal impact of a practice pattern for secundum atrial septal defect repair in children. Am J Cardiol 1994;74:512–4.[Medline]
9. Kirklin JW, Blackstone EH, Jonas RA, et al. Morphologic and surgical determinants of outcome events after repair of tetralogy of Fallot and pulmonary stenosis: a two institution study. J Thorac Cardiovasc Surg 1992;103:706–23.[Abstract]
10. Ungerleider RM, Kanter RJ, Bengur AR, et al. Effect of repair strategy on hospital cost for infants with tetralogy of Fallot. Ann Surg (in press).

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This Article Abstract Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Ross M. Ungerleider James Jaggers Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Ungerleider, R. M. Articles by Greeley, W. J. Search for Related Content PubMed PubMed Citation Articles by Ungerleider, R. M. Articles by Greeley, W. J. Related Collections Related Article