Surveillance of surgical site infection after colorectal surgery: comprehensiveness and impact of risk factors.

Objective: The incidence of surgical site infection (SSI) is highest after colorectal surgery. We assessed the impact of risk factors for SSI using the population attributable fraction (PAF).

Design: Retrospective cohort study.

Setting: Portuguese hospitals performing regular surveillance.

Patients: We identified patients who underwent colorectal procedures in hospitals that reported colorectal surgeries every year between 2015 and 2019. Among 42 reporting hospitals, 18 hospitals were included.

Methods: Risk-factor incidence was estimated using the National Epidemiological Surveillance platform from 2015 to 2019. This platform follows the methodology recommended by the European Centre for Disease Prevention and Control. American Society of Anaesthesiologists (ASA) physical classification, wound classification, open surgery, urgent operation, antibiotic prophylaxis, operation time, and male sex were included as risk factors. Measures of association were retrieved from published meta-analyses. PAFs were calculated using the Levin formula. To account for interaction between risk factors, communality of risk factors was used in a weighted-sum approach, providing a combined value that serves as a measure of the comprehensiveness of surveillance.

Results: Among 11,219 reported procedures, the cumulative SSI incidence was 16.8%. The proportion of SSI attributed to all risk factors was 61%. Modifiable variables accounted for 31% of procedures; the highest was laparotomy (16.8%), and urgent operations (2.7%) had the lowest value. Nonmodifiable factors accounted for 28.7%; the highest was wound classification (14.3%).

Conclusions: A relevant proportion (39%) of SSI remains unaccounted for by current surveillance. Almost one-third of SSI cases have potentially modifiable factors. Interventions focusing on shorter, less invasive procedures may be optimally effective in reducing the SSI incidence.