Predictive Validity of National Nosocomial Infection Surveillance (NNIS) and Study on the Efficacy of Nosocomial Infections (SENIC) Risk Indexes for the Incidence of Surgical Site Infections (SSI) in General Surgery at Hospital Universiti Sains Malaysia (HUSM)

Abstract

A827 conducted at HUSM including all patients undergoing general surgery serially between ages 18-75 years during 6 months duration. Patients who died before or during surgery and those who failed to come for follow-up were excluded. Each patient was under constant surveillance from the date of admission until 30 days post-operatively. SSI was defined as per Centers of Disease Control (CDC), USA criteria. Patients were stratified into risk groups according to SENIC and NNIS risk scoring index. Statistical analysis was done using SPSS version 20. Results: Out of total 180 patients enrolled, 23 (12.8%) developed SSI. Abdominal procedures had highest rate of SSI (65.2% of total SSI cases). NNIS index stratified 90 (50%) patients at risk of developing post-operative infection while SENIC identified 136 (75.6%) patients at risk. For NNIS, incidence of SSI in low, medium and high risk patients was 2.2%, 16.4% and 43.5% and for SENIC index it was 4.5%, 9.6% and 24.5% respectively. 15.4% patients had SSI who were stratified at risk by SENIC while NNIS risk group had 23.3% cases of SSI. Surprisingly, sensitivity of both indexing tools came out to be 91.3% (CI: 71.9%-98.9%) which is quite good however specificity was low (26.8%, CI: 20.0%-34.4%) for SENIC and comparatively high for NNIS (56.1%, CI: 47.9%-63.9%). Receiver operating characteristic (ROC) curve for the calculated risk in SENIC and NNIS models was derived and area-under-the-curve was larger for the NNIS model (Area: 0.799, p < 0.001). ConClusions: Both NNIS and SENIC are significant risk indexes and should be utilized concurrently, however NNIS proved to be more reliable index in our settings.