The cost-effectiveness of ertapenem for the treatment of chorioamnionitis after cesarean delivery

Background: Chorioamnionitis affects 1-4% of pregnancies, and patients who undergo cesarean delivery in the setting of chorioamnionitis have an increased risk of endometritis and surgical site infection (SSI). The standard treatment for chorioamnionitis after cesarean delivery is a combination regimen of intravenous ampicillin, gentamicin, and clindamycin with variable duration (single dose to 24 h). However, newer evidence suggests that ertapenem may decrease the risk of postoperative infectious morbidity with the added benefit of a single postpartum dose, compared to between 3 and 10 doses of AGC. Concerns regarding the cost of ertapenem have been cited as a deterrent for this regimen. Objective: The objective of this study was to investigate the cost-effectiveness of single-dose ertapenem compared to existing standard regimens. Methods: A decision analytic cost-effectiveness model was designed from a hospital perspective to compare four strategies for the postpartum management of chorioamnionitis after cesarean delivery: (i) no antibiotics; (ii) a one-time intravenous dose of ampicillin, gentamicin, and clindamycin (AGC-1); (iii) 24-h coverage with intravenous ampicillin, gentamicin, and clindamycin (AGC-24); and (iv) intravenous ertapenem, one dose. Medical costs, rates of SSI and endometritis following cesarean delivery, and costs of postcesarean infection (SSI or endometritis) were abstracted from the literature. Antibiotic drug costs were obtained from the pharmacy department at a private academic hospital. The cost of each regimen was calculated as costs to the hospital and included antibiotics (no antibiotics $0, AGC-1 $66, ertapenem $140, and AGC-24 $208), administration, and labor costs. Effectiveness was quantified as percentage of patients who avoided postcesarean infectious morbidity (endometritis or SSI). Results: The base case cost of each strategy was: AGC-1 $704, ertapenem $733, AGC-24 $846, and no antibiotics $971. Ertapenem had an effectiveness of 88%, AGC-1 and AGC-24 were 87% each, and no antibiotics was 81%. No antibiotics and AGC-24 were more costly and equally or less effective than comparators (dominated strategies). Ertapenem was more costly, but more effective than AGC-1, with an incremental cost-effectiveness ratio of $3738 per infection avoided. In a sensitivity analysis comparing ertapenem to the most commonly used strategy of ACG-24, the ertapenem strategy remained less costly if the rate of endometritis with ertapenem was <11% (base case estimate 8%) or the rate of SSI with ertapenem was <7% (base case estimate 4%). Conclusions: Ertapenem is a cost-saving alternative to 24-h AGC treatment for chorioamnionitis in the setting of cesarean delivery, and may be considered a cost-effective treatment when compared to a one time dose of AGC depending on infection rates.