A Simplified Cost-Utility Analysis of Inpatient Flap Monitoring after Microsurgical Breast Reconstruction and Implications for Hospital Length of Stay.

Background: The number of free flap take-backs and successful salvages following microsurgical breast reconstruction decreases as time from surgery increases. As a result, the cost of extended inpatient monitoring to achieve a successful flap salvage rises rapidly with each postoperative day. This study introduces a simplified cost-utility model of inpatient flap monitoring and identifies when cost-utility exceeds the thresholds established for other medical treatments.

Methods: A retrospective review of a prospectively maintained database was performed of patients who underwent microsurgical breast reconstruction to identify flap take-back and salvage rates by postoperative day. The number of patients and flaps that needed to be kept on an inpatient basis each day for monitoring to salvage a single failing flap was determined. Quality-of-life measures and incremental cost-effectiveness ratios for inpatient flap monitoring following microsurgical breast reconstruction were calculated and plotted against a $100,000/quality-adjusted life-year threshold.

Results: A total of 1813 patients (2847 flaps) were included. Overall flap take-back and salvage rates were 2.4 percent and 52.3 percent, respectively. Of the flaps taken back, the daily take-back and salvage rates were 56.8 and 60.0 percent (postoperative day 0 to 1), 13.6 and 83.3 percent (postoperative day 2), 11.4 and 40.0 percent (postoperative day 3), 9.1 and 25.0 percent (postoperative day 4), and 9.1 and 0.0 percent (>postoperative day 4), respectively. To salvage a single failing flap each day, the number of flaps that needed to be monitored were 121 (postoperative day 0 to 1), 363 (postoperative day 2), 907 (postoperative day 3), 1813 (postoperative day 4), and innumerable for days beyond postoperative day 4. The incremental cost-effectiveness ratio of inpatient flap monitoring begins to exceed a willingness-to-pay threshold of $100,000/quality-adjusted life-year by postoperative day 2.

Conclusion: The health care cost associated with inpatient flap monitoring following microsurgical breast reconstruction begins to rise rapidly after postoperative day 2.