What is SSI risk index?

Each operation is scored by the presence or absence of three risk factors at the time of surgery: 1. American Society of Anaesthesiologists’ (ASA) preoperative assessment score of 3 or more (this indicates the patient has a severe underlying systematic disease) 2. Operation is classified as contaminated or dirty 3. Operation lasts for more than a specific period of time (‘T hours’), where T is the 75th percentile of the duration of surgery and depends on the surgical procedure being performed (e.g. hip replacement T time=2 hours) Each of the risk factors described above contributes one point to the risk index score, which ranges from 0 (none of the risk factors present) to 3 (all of the risk factors present