Comparison of Surveillance of Surgical Site Infections by a National Surveillance Program and by Institutional Audit.

Background: Reported incidence of surgical site infections (SSI) after colonic surgery varies widely. These variations depend not only on patient- and surgery-related parameters but are influenced by type and quality of follow-up. The aim of the study was to compare SSI assessed by two independent prospective surveillance systems, a national surveillance program based on recommendations of the National Healthcare Safety Network (Swissnoso) versus an international audit system, the ERAS Interactive Audit System (EIAS; Encare, Stockholm, Sweden).

Methods: Comparative study of a consecutive cohort of colonic resections at a single institution from September 2015 to March 2017. Independent prospective SSI monitoring was available from Swissnoso and EIAS. Inter-observer reliability was calculated using Cohen k. Sensitivity, specificity, and accuracy of EIAS in assessing SSI was compared with Swissnoso, considered as gold standard.

Results: The final sample included 143 patients. Of these, 136 (95.1%) were classified into the same category by both systems, identifying 17 patients (12.5%) with SSI and 119 patients (87.5%) without SSI, respectively. Discrepant results were found for the remaining seven patients (4.9%) with four SSI categorization according to Swissnoso but not EIAS, and three SSI categorization in EIAS but not in Swissnoso; all miscategorized patients presented superficial SSI. Sensitivity, specificity, and accuracy of EIAS for SSI recording was 81%, 97.5%, and 95.1%, respectively. Inter-observer agreement was high (Cohen k value of 0.801, p < 0.001). Case-by-case analysis of discrepant findings revealed mainly discrepant interpretation of clinical symptoms and erroneous labeling of non-procedure-related infections.

Conclusions: Surgical site infection recording by two independent systems showed high concordance and good inter-rater reliability.