J. J. Cedarbaum1, L. Ly1, R. Anand1, A. Hjelmaas1, Y. Chen1, S. Collins1, S. Regenbogen1 1University Of Michigan,University Of Michigan Health System,Ann Arbor, MI, USA
Introduction:
Obesity is a substantial risk factor for surgical site infections (SSIs). Antibiotic prophylaxis guidelines recommend weight-based dosing as one way to mitigate this risk. However, there is little clinical evidence to support this practice, and data on compliance is rarely collected in clinical registries. Using data from a population-based, statewide collaborative, we sought to evaluate the association between appropriate weight-based perioperative antibiotic dosing and the risk of SSI after colectomy.
Methods:
From a retrospective cohort from 73 hospitals in the Michigan Surgical Quality Collaborative (MSQC), we included all patients who underwent elective colectomy between 2012 and 2015. The primary outcome was the development of SSI within 30 days of surgery. SSI rates were compared between patients who did and did not receive compliant weight-based dosing.
Results:
Of the 4,801 patients included, 4,627 (96%) had appropriate weight-based dosing of perioperative antibiotics. Patients who received proper weight-based dosing had an overall SSI rate of 6.2% while those who did not receive weight-based dosing had an observed SSI rate of 9.8% (p=0.15). When evaluating only patients requiring dose-adjustment (those weighing in excess of 80kg, N=2,179), observed SSI rates were 6.9% with compliant weight-based dosing, versus 9.8% for non-compliant dosing (p=0.17). In post-hoc power analysis, there was only 30% power to detect this magnitude of difference in SSI rates for the >80kg subset.
Conclusion:
Weight-based dosing is already commonly used among MSQC hospitals. As a result of the small proportion of patients in the non-compliant dosing group, we did not detect a statistically significant reduction in the incidence of SSI among those with appropriate antibiotic dosing, although the relative risk of SSI was 30% less. As additional data on weight-based dosing compliance becomes available in MSQC we will return to this important question in order to make a more convincing determination as to the efficacy of this practice.
