Isabel HGA, Antonio CG, Álvaro LH, et al. - Given that demand for hip arthroplasty has increased which indicates the increasing number of post surgical complications, researchers here examined risk of surgical site infection (SSI) in a teaching hospital; developed regional, national and international external comparisons; and investigated related SSI-risk factors, especially in accordance to the timing of surgery (urgent/unplanned or elective). From January 2008 to December 2018, they identified 1,808 patients for inclusion in this study. An overall SSI rate of 3.0% was noted in this study population. Per observations, hospital-based infection surveillance is an important component for of surgical site infection control. Timing of surgery caused an effect modification, so independent risk factors in the urgent/unplanned group were surgery duration > 75 th percentile and inadequate preparation; independent risk factors in the elective group were NHSN risk index ≥ 2 and transfusion. Characterization of these factors may aid recognition of areas of quality improvement, including reducing operating times, preventing perioperative blood transfusion, or improving patient preparation before surgery.