Abstract and Introduction
Abstract
Study Objective: To determine if appropriate timing of vancomycin prophylaxis in patients undergoing cardiovascular surgery results in an economic benefit by assessing the differences in total duration of hospitalization and hospital costs based on infusion start time in relation to first surgical incision.
Design: Prospective, observational study.
Setting: Tertiary care medical center.
Patients: A total of 1666 patients undergoing coronary artery bypass graft (CABG) and/or valve replacement surgery who received prophylactic vancomycin.
Measurements and Main Results: Appropriateness of vancomycin prophylaxis timing, based on national guidelines defining appropriate timing as start time of infusion ranging from 16-120 minutes before surgery start time, was prospectively monitored. The timing of vancomycin administration was grouped as follows: 0-15 minutes (11 patients), 16-60 minutes (156), 61-120 minutes (772), or more than 120 minutes (727) before incision. Antibiotic timing was appropriate in 928 patients and inappropriate in 738 patients. Length of hospital stay and total hospital costs were compared based on appropriateness of therapy by using multivariate linear regression and validated with a Heckman two-stage model. Median numbers of hospitalization and intensive care unit days were significantly fewer in patients given appropriate prophylaxis at an appropriate time (9 and 2 days, respectively) compared with inappropriate time (10 and 3 days, respectively, p<0.001 for both analyses). Hospital costs were significantly lower in patients who had appropriate timing of antibiotic prophylaxis (median $25,321, interquartile range [IQR] $19,429-35,471) compared with inappropriate timing (median $29,475, IQR $21,507-46,488, p<0.001). Multivariate linear regression and a Heckman two-stage model confirmed that appropriate antibiotic prophylaxis timing was associated with decreased hospitalization duration and hospital costs.
Conclusion: In patients undergoing CABG or valve replacement surgery, the administration of vancomycin 16-120 minutes before incision significantly reduced patient hospitalization duration and total hospital costs.
Introduction
Antibiotic prophylaxis is recommended for patients undergoing cardiac surgery to prevent postoperative surgical site infections (SSIs). Cephalosporin antibiotics are recommended because of their in vitro activity against the most commonly isolated organisms, favorable toxicity profile, and cost. Vancomycin can be used for patients with a β-lactam allergy or in hospitals with a high rate of infections caused by methicillin-resistant Staphylococcus species. The guidelines recommend that the antibiotic infusion should begin within 60 minutes before the surgical start time for cephalosporins and within 120 minutes for vancomycin. Clinical evidence to support this recommendation for cephalosporins stems from a study of 2847 patients undergoing clean or clean-contaminated surgery who were prospectively monitored for the timing of antibiotic prophylaxis and the occurrence of SSIs. This study demonstrated that administration of antibiotics during the 2 hours before surgical incision was associated with the lowest rate of SSIs compared with administration of antibiotics postoperatively or at earlier time periods before the surgical incision.
The authors of another study combined the results of two prospective, randomized trials of 221 patients undergoing surgery of the gastrointestinal tract and investigated the role of antibiotic prophylaxis timing. In this study, administration of antibiotics within 16-60 minutes was associated with the lowest rates of infectious complications. A recent study of 2048 patients undergoing coronary artery bypass graft (CABG) or valve replacement surgery showed that a vancomycin infusion started 16-60 minutes before the surgical incision was associated with the lowest rate of SSIs. The rate of SSIs was highest if the vancomycin infusion was started 0-15 minutes before the start of surgery.
There are likely economic benefits from appropriate antibiotic prophylaxis timing. In a cohort study of 479 patients undergoing surgery, total hospital costs were assessed. Median hospital costs were $29,455 for uninfected patients, $52,791 for patients with SSIs caused by methicillin-sensitive S. aureus, and $92,363 for patients with SSIs caused by methicillin-resistant S. aureus. Another study of 201 patients undergoing CABG surgery estimated the cost of a deep chest SSI at $18,938 after controlling for important confounders. However, to our knowledge, no previous study has demonstrated that appropriate antibiotic timing can decrease overall hospitalization costs. Because there is a significant potential to decrease SSIs by improving the timing of antibiotic surgical prophylaxis, we sought to assess the impact of appropriate antibiotic timing on hospital costs and length of hospital stay. We performed a single-center cohort study of patients undergoing cardiac surgery. The goal of our analysis was to determine if appropriate timing of vancomycin prophylaxis in patients undergoing cardiovascular surgery results in an economic benefit by assessing the differences in total duration of hospitalization and hospital costs based on infusion start time in relation to first surgical incision.