Risk factors for higher cost in congenital heart operations

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.

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.

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.

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.