The measures reflects the percent of patients receiving spine surgery for whom there is medical record evidence of use of evidence-based interventions to prevent surgical site infection (SSI). SSI is a relatively rare but serious complication of surgery, and is preventable to some extent by specific pre-surgical site preparation done by patients the day before surgery. Data from MSSIC suggests significant variability among surgeons and among hospitals in terms of the percent of patients for whom a formal pre-surgical wash preparation is used.