Epidemiology of Surgical Site Infections With Staphylococcus aureus in Europe: Protocol for a Retrospective, Multicenter Study

Background: Surgical site infections (SSIs) are among the most common hospital acquired infections. While the incidence of SSI in certain indicator procedures is the subject of ongoing surveillance efforts in hospitals and health care systems around the world, SSI rates vary markedly within surgical categories and are poorly represented by routinely monitored indicator procedures (eg, mastectomy or hernia surgery). Therefore, relying on indicator procedures to estimate the burden of SSI is imprecise and introduces bias as hospitals may take special precautions to achieve lower SSI rates. The most common cause of SSI is Staphylococcus aureus (S. aureus), as recently confirmed by a Europe-wide point-prevalence study conducted by the European Centre for Disease Prevention and Control (ECDC). Objective: The primary objective of this study is to determine the overall and procedure-specific incidence of S. aureus SSI in Europe. Secondary objectives are the overall and procedure-specific outcomes as well as the economic burden of S. aureus SSI in Europe. Explorative objectives are to characterize the composition of the surgical patient population and to estimate the number of patients at risk for S. aureus SSI. Methods: A retrospective, multinational, multicenter cohort study (Staphylococcus aureus Surgical Site Infection Multinational Epidemiology in Europe [SALT] study) with a nested case-control part will be conducted. The study will include all surgical procedures at a participating center in order to prevent selection bias and strengthen the understanding of SSI risk by determining the incidence for all common surgical procedures. Data will be assessed in the cohort population, including 150,000 adult patients who underwent any surgical procedure in 2016, and the case-control population. We will match patients establishing S. aureus SSI 1:1 with controls from the same center. Data on demographics, surgery, and microbiology will be exported from electronic files. More detailed data will be captured from the case-control population. The SALT study will include 13 major or academic surgical centers in Europe, comprising 3 in France, 4 in Germany, 2 in Italy, 3 in Spain, and 1 in the United Kingdom. Sites were selected using a feasibility questionnaire. Results: The SALT study is currently recruiting patients. The aim is to complete recruitment in February 2018 and to close the database in September 2018. The final results are expected by the end of 2018. Conclusions: Results of the SALT study will help to better understand the precise risk of certain procedures. They will also provide insight into the overall and procedure-specific incidence and outcome as well as the economic burden of S. aureus SSI in Europe. Findings of the study may help guide the design of clinical trials for S. aureus vaccines.