301. The cost-effectiveness of antibiotic infection prophylaxis in same-day anterior cervical discectomy and fusion

Abstract

BACKGROUND CONTEXT Outpatient anterior cervical discectomy and fusion (ACDF) is associated with dramatically lower costs than the same procedure in the inpatient setting. Nevertheless, postoperative infection remains a concern due to its devastating medical and economic effects. PURPOSE This studying aimed to assess the cost-effectiveness of standard antibiotic protocols for preventing infection following same-day ACDF. STUDY DESIGN/SETTING Break-even cost analysis. OUTCOME MEASURES This study determined the magnitude by which the rate of infection following same-day ACDF would need to be reduced by in order to make application of standard antibiotic infection prophylaxis cost-effective. METHODS The product cost of 2g of intravenous cephazolin was obtained from our institution s purchasing records. Average retail costs of oral cephalexin (500mg every 6 hours) for 1, 3 and 5 days were obtained from open access pharmacy data. Four total protocols were assessed: preoperative intravenous cephazolin alone, as well as preoperative intravenous cephazolin with either 1, 3 or 5 days of postoperative oral cephalexin. Baseline infection rate following same-day ACDF and average direct costs for treating ACDF infection were obtained from the literature. A break-even analysis [break-even infection rate\u202f=\u202f(initial infection rate - cost of protocol) / cost of treatment] was then utilized to determine the absolute risk reduction (ARR) needed in infection rate to make each protocol cost-effective. RESULTS At $1.64 at our institution, the use of 2g of intravenous cephazolin is economically justified if the initial infection rate (0.20%) of same-day ACDF is lowered by an ARR of 0.02%. Adding one day of oral cephalexin at an average retail price of $11.18 would require an ARR of 0.10% to be cost-effective. At an average retail price $15.68 to add three days of oral cephalexin, an ARR of 0.10% is needed to make the protocol cost-effective. Furthermore, adding five days of oral cephalexin at an average retail price of $20.45 would require an ARR of 0.19% to be economically justified. CONCLUSIONS This break-even analysis demonstrates that preoperative intravenous cephazolin is an economically viable method for preventing infection following same-day ACDF. At our institution s price point, use of preoperative cephazolin is economically justified if is prevents at least one infection for every 5,000 ACDF surgeries. Meanwhile, adding postoperative oral antibiotic prophylaxis to this regimen requires reducing the infection rate by greater than or equal to half the initial rate. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.