infection control and hospital epidemiology july 2007, vol. 28, no. 7 original article Validation of Coronary Artery Bypass Graft Surgical Site Infection Surveillance Data From a Statewide Surveillance System in Australia N. Deborah Friedman, MBBS, FRACP; Philip L. Russo, MClinEpid; Ann L. Bull, PhD; Michael J. Richards, MBBS, FRACP, MD; Heath Kelly, MBBS, MPH, FAFPHM objective. To measure the accuracy and determine the positive predictive value (PPV) and negative predictive value (NPV) of data submitted to a statewide surveillance system for identifying surgical site infection (SSI) complicating coronary artery bypass graft (CABG) surgery. design. Retrospective review of hospital medical records comparing SSI data with surveillance data submitted by infection control consultants (ICCs). setting. Victorian Hospital Acquired Infection Surveillance System (VICNISS) Coordinating Centre in Victoria, Australia. patients. All patients reported to have an SSI following CABG surgery and a random sample of approximately 10% of patients reported not to have an SSI following CABG surgery. results. The VICNISS ascertainment rate for CABG procedures in Victoria was 95%. One hundred sixty-nine medical records were reviewed, and reviewers agreed with ICCs about 46 (96%) of the patients reported as infected by the ICCs and 31 (91%) of the patients identified with a sternal SSI by the ICCs. In one-third of SSIs, the depth of SSI documented by ICCs was discordant with that documented by the reviewers. Disagreement about patients with donor site SSI was frequent. When the review findings were used as the reference standard, the PPV for ICC-reported SSI was 96% (95% confidence interval [CI], 86%-99%), and the NPV was 97% (95% CI, 92%-99%). For ICC-reported sternal SSI, the PPV was 91% (95% CI, 76%-98%) and the NPV was 98% (95% CI, 94%-100%). conclusions. There was broad agreement on the number of infected patients and the number of patients with sternal SSI. However, discordance was frequent with respect to the depth of sternal SSI and the identification of donor site SSI. We recommend modifications to the methodology for National Noscomial Infection Surveillance System–based surveillance for SSI following CABG surgery. Infect Control Hosp Epidemiol 2007; 28:812-817 From the Victorian Hospital Acquired Infection Surveillance System Coordinating Centre (N.D.F., P.L.R., A.L.B., M.J.R.) and the Victorian Infectious Diseases Reference Laboratory (H.K.), Melbourne, Victoria, Australia. Received October 11, 2006; accepted November 28, 2006; electronically published May 17, 2007.  2007 by The Society for Healthcare Epidemiology of America. All rights reserved. 0899-823X/2007/2807-0007$15.00. DOI: 10.1086/518455 Surgical site infection (SSI) is the second most common hos- pital-acquired infection (HAI), and adds to length of hos- pitalization. Effective infection control surveillance systems using standard definitions, which return site-specific, risk- adjusted SSI rates, may contribute to the prevention of HAI. 1 Review of surveillance data is necessary to ensure its scientific credibility, to identify methodological problems, and to iden- tify data quality issues at a local level. 2 No previous validation studies have focused solely on SSI complicating coronary ar- tery bypass graft (CABG) procedures. Many different HAI surveillance methods exist for detect- ing SSI, including retrospective chart review, 3 laboratory- based ward surveillance, 4 daily ward rounds with examination of temperature charts and wounds, and ward liaison sur- veillance. 4 The best results have been obtained by reviewing microbiology reports and regular ward liaison surveillance. 4 The Victorian Hospital Acquired Infection Surveillance System (VICNISS) was established in 2002 and collates SSI surveillance data in the state of Victoria, Australia. Six hos- pitals perform a total of approximately 2,000 CABG proce- dures annually, 5 and infection control consultants (ICCs) at these sites have been performing surveillance since 1998. 6 VICNISS reports on SSIs that are detected during the inpa- tient stay or on readmission, but excludes SSIs detected by postdischarge surveillance. The objectives of our study were to measure the accuracy of the recorded data and the completeness of denominator data, and to determine the positive predictive value (PPV) and the negative predictive value (NPV) of SSI surveillance data submitted to VICNISS by ICCs for identifying SSI com- plicating CABG surgery. We also estimated the sensitivity and specificity of the detection of SSI following CABG surgery and examined the convention of using the VICNISS review findings as the reference standard (or de facto “gold standard”).