PROJECT SUMMARY / ABSTRACT More than 500,000 patients acquire Surgical Site Infections (SSIs) each year, making them the leading cause of hospital-acquired infections. SSIs account for billions of dollars in added health care costs and are associated with up to 11 times higher risk of post-surgical mortality. Despite near universal adherence to Surgical Care Improvement Project (SCIP) guidelines for prophylactic antibiotic administration, SSI rates remain stagnant. As compared to SCIP, the Infectious Disease Society of America (IDSA) provides far more comprehensive guidelines for surgical antibiotic prophylaxis. Beyond the SCIP measures, which focus mostly on antibiotic timing with respect to surgical incision, IDSA guidelines additionally include: 1) more specific antibiotic selection for several surgical procedures, 2) weight-adjusted antibiotic dosing, and 3) timely antibiotic re-dosing during prolonged surgeries. Each of these is a crucial aspect of antibiotic administration and is not addressed by SCIP guidelines that inform the majority of perioperative antibiotic practice. In preliminary work using a national dataset, we found that non-adherence to at least one of the components of IDSA guidelines occurred in over one-third of surgical cases. We also found that IDSA non-adherence is markedly higher during unplanned scenarios such as surgeries involving multiple blood product transfusions and emergency surgeries indicating there may be a situational component to the non-adherence. We believe promoting adherence to IDSA guidelines can markedly reduce SSIs and can be achieved by targeting healthcare provider workflow barriers and knowledge deficits using a provider centered clinical decision support (CDS) tool. We propose to - Aim 1: Measure the association of nonadherence to IDSA guidelines and its components (antibiotic choice, timing, dosing, and intraoperative redosing) with SSI occurrence by analyzing merged data from two robust national registries: the National Surgical Quality Improvement Program (NSQIP), which captures detailed postoperative outcomes, with the Multicenter Perioperative Outcomes Group (MPOG) that captures detailed perioperative data. Additionally, we will examine differences in nonadherence (disparities in care) across several AHRQ priority groups to identify opportunities for SSI reduction within these subgroups. Aim 2: Identify factors associated with deviation from IDSA guidelines in practice through semi structured interviews of perioperative healthcare providers and incorporate these to develop a CDS tool that promotes IDSA adherent antibiotic practices. Aim 3: Assess the real-world performance of the CDS tool and provider feedback using the RE-AIM (Reach, Effectiveness, Adoption, Implementation, Maintenance) framework of implementation evaluation. Public Health Significance: SSIs are common, costly, and largely avoidable. The proposed study will a) help determine relationships between IDSA guideline nonadherence ...