Determinants of Value in Coronary Artery Bypass Grafting

Abstract

Background Over 180 000 coronary artery bypass grafting (CABG) procedures are performed annually, accounting for $7 to $10 billion in episode expenditures. Assessing tradeoffs between spending and quality contributing to value during 90-day episodes has not been conducted but is essential for success in bundled reimbursement models. We, therefore, identified determinants of variability in hospital 90-day episode value for CABG. Methods Medicare and private payor admissions for isolated CABG from 2014 to 2016 were retrospectively linked to clinical registry data for 33 nonfederal hospitals in Michigan. Hospital composite risk-adjusted complication rates (≥1 National Quality Forum-endorsed, Society of Thoracic Surgeons measure: deep sternal wound infection, renal failure, prolonged ventilation >24 hours, stroke, re-exploration, and operative mortality) and 90-day risk-adjusted, price-standardized episode payments were used to categorize hospitals by value by defining the intersection between complications and spending. Results Among 2573 total patients, those at low- versus high-value hospitals had a higher percentage of prolonged length of stay >14 days (9.3% versus 2.4%, P=0.006), prolonged ventilation (17.6% versus 4.8%, P<0.001), and operative mortality (4.8% versus 0.6%, P=0.001). Mean total episode payments were $51 509 at low-compared with $45 526 at high-value hospitals (P<0.001), driven by higher readmission ($3675 versus $2177, P=0.005), professional ($7462 versus $6090, P<0.001), postacute care ($7315 versus $5947, P=0.031), and index hospitalization payments ($33 474 versus $30 800, P<0.001). Among patients not experiencing a complication or 30-day readmission (1923/2573, 74.7%), low-value hospitals had higher inpatient evaluation and management payments ($1405 versus $752, P<0.001) and higher utilization of inpatient rehabilitation (7% versus 2%, P<0.001), but lower utilization of home health (66% versus 73%, P=0.016) and emergency department services (13% versus 17%, P=0.034). Conclusions To succeed in emerging bundled reimbursement programs for CABG, hospitals and physicians should identify strategies to minimize complications while optimizing inpatient evaluation and management spending and use of inpatient rehabilitation, home health, and emergency department services.

Keywords: coronary artery bypass; hospitalization; inpatient; length of stay; pneumonia.

Figure 1.

Deviation from centered mean in complication rate (x-axis) and total episode payments (y-axis). Plotted dots are weighted by hospital volume of isolated coronary artery bypass grafting procedures. Quadrants are labeled as “high” or “low” spending and complication rates. Complications included any of the following: deep sternal wound infection, renal failure, prolonged ventilation (>24 hours), stroke, surgical re-exploration, and operative mortality. Centers in the high spending and high complication rate quadrant are considered “low-value,” while those in the low spending and low complication rate quadrant are considered “high-value.” Pearson-weighted correlation coefficient=0.51.

Figure 2.

Variation in total and component 90-day episode payments after coronary artery bypass grafting in low- and high-value hospitals among the overall population (n=2573) and only patients who did not experience a complication or get readmitted within 30 days (n=1923). Complications included any of the following: deep sternal wound infection, renal failure, prolonged ventilation (>24 hours), stroke, surgical re-exploration, and operative mortality. Post-acute care payments include inpatient and outpatient rehabilitation, home health, skilled nursing facility, emergency department, and other outpatient facility payments.