Risk factors for surgical site infections in a free-standing outpatient setting

More information about risk factors for surgical site infections in outpatient settings is necessary for creation of surveillance systems in this field.

The aim of this study was to determine the incidence of surgical site infections (SSI) in an outpatient setting and to investigate whether the risk index of the National Nosocomial Infections Surveillance (NNIS) System is appropriate for outpatient settings.

A retrospective cohort design was used to investigate SSI following all hernia repairs and varicose veins operations over a 9-year period in a freestanding outpatient setting. The exposure variables studied were age, sex, and American Society of Anesthesiologists (ASA) score of the patient; duration of operation; performing surgeon's name; type of operation; type of anesthesia; and follow-up period. An univariable and a multivariable analysis were performed to determine risk factors for SSI.

A total of 1095 operations were performed: 714 on varicose veins and 381 on hernia repairs. The median follow-up period was 43 days. The crude SSI rate was 1.2% (varicose veins operations, 1.5%; hernia repair operations, 0.5%). According to the results of the logistic regression model, only 1 factor remained significant: Patients with spinal anesthesia were 11 times as likely to develop a SSI as patients with any other type of anesthesia (95% CI, 2.15-200.5).

The NNIS risk index was not suitable for assessing SSI rates in this outpatient setting and for these specific procedures.