Hospital context in surgical site infection following colorectal surgery: a multi-level logistic regression analysis

Surgical site infections (SSIs) are associated with poor health outcomes. Their incidence is highest after colorectal surgery, with little improvement in recent years. The role of hospital characteristics is undetermined.

To investigate whether SSI incidence after colorectal surgery varies between hospitals, and whether such variance may be explained by hospital characteristics.

Data were retrieved from the electronic platform of the Directorate General of Health, from 2015 to 2019. Hospital characteristics were retrieved from publicly available data on the Portuguese public administration. Analysis considered a two-level hierarchical data structure, with individuals clustered in hospitals. To avoid overfitting, no models were built with more than one hospital characteristic. Cluster-level associations are presented through median odds ratio (MOR) and intraclass cluster coefficient (ICC). Beta coefficients were used to assess the contextual effects.

A total of 11,219 procedures from 18 hospitals were included. The incidence of SSI was 16.8%. The ICC for the null model was 0.09. Procedural variables explained 25% of the variance, and hospital dimension explained another 17%. More than 50% of SSI variance remains unaccounted for. After adjustment, heterogeneity between hospitals (MOR: 1.51; ICC: 0.05) was still found. No hospital characteristic was significantly associated with SSI.

Procedural variables and hospital dimension explain almost half of SSI variance and should be taken into account when implementing prevention strategies. Future research should focus on compliance with preventive bundles and other process indicators in hospitals with significantly less SSI in colorectal surgery.