Adherence to Guidelines for the Administration of Intraoperative Antibiotics in a Nationwide US Sample.Importance
 Despite widespread adherence to Surgical Care Improvement Project antibiotic measures, prevention of surgical site infections (SSIs) remains a clinical challenge.  Several components of perioperative antibiotic prophylaxis guidelines are incompletely monitored and reported within the Surgical Care Improvement Project program.


 Objectives
 To describe adherence to each component of perioperative antibiotic prophylaxis guidelines in regard to procedure-specific antibiotic choice, weight-adjusted dosing, and timing of first and subsequent administrations in a nationwide, multicenter cohort of patients undergoing noncardiac surgery.


 Design, Setting, and Participants
 This cohort study included adult patients undergoing general, urological, orthopedic, and gynecological surgical procedures involving skin incision between January 1, 2014, and December 31, 2018, across 31 academic and community hospitals identified within the Multicenter Perioperative Outcomes Group registry.  Main Outcomes and Measures
 The primary end point was overall adherence to Infectious Diseases Society of America guidelines, including (1) appropriateness of antibiotic choice, (2) weight-based dose adjustment, (3) timing of administration with respect to surgical incision, and (4) timing of redosing when indicated.  Data were analyzed using mixed-effects regression to investigate patient, clinician, and institutional factors associated with guideline adherence.


 In the final cohort of 414 851 encounters across 31 institutions, 51.8% of patients were women, the mean (SD) age was 57.5 (15.7) years, 1.2% of patients were of Hispanic ethnicity, and 10.2% were Black.  In this cohort, 148 804 encounters (35.9%) did not adhere to guidelines: 19.7% for antibiotic choice, 17.1% for weight-adjusted dosing, 0.6% for timing of first dose, and 26.8% for redosing.  In adjusted analyses, overall nonadherence was associated with emergency surgery (odds ratio [OR], 1.35; 95% CI, 1.29-1.41; P < .001), surgery requiring blood transfusions (OR, 1.30; 95% CI, 1.25-1.36; P < .001), off-hours procedures (OR, 1.08; 95% CI, 1.04-1.13; P < .001), and procedures staffed by a certified registered nurse anesthetist (OR, 1.14; 95% CI, 1.11-1.17; P < .001).  Overall adherence to guidelines for antibiotic administration improved over the study period from 53.1% (95% CI, 52.7%-53.5%) in 2014 to 70.2% (95% CI, 69.8%-70.6%) in 2018 (P < .001).


 Conclusions and Relevance
 In this cohort study, although adherence to perioperative antibiotic administration guidelines improved over the study period, more than one-third of surgical encounters remained discordant with Infectious Diseases Society of America recommendations.  Future quality improvement efforts targeting gaps in practice in relation to guidelines may lead to improved adherence and possibly decreased SSIs.
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