Title of Project: Did we cause that colon surgical site infection (SSI) or was it PATOS (present at time of surgery)?

Authors:
Anne Macy, Bonita Allen, David Gemmel, Jennifer Yockey, Lillianne Stanitsas

Body of Abstract:
Background: Complex PATOS SSIs are distinct from complex non-PATOS SSIs and are excluded from the SIR (Standard infection ratio) to ensure accurate hospital comparisons. For PATOS, intraoperative infection evidence must be documented within the operative body or findings. Per NHSN guidelines pathology, imaging and cultures alone cannot confirm PATOS; however, these criteria are used to diagnose an SSI.

Methods: Retrospective cohort chart audit analyzed 1379 colon-coded procedures from 27 hospitals from May 2023 to Jan 2024. Charts were audited from three days pre- surgery to 30 days post-surgery following NHSN surveillance guidelines. Data abstraction was performed by a surgical critical care provider and system wide infection preventionists. Inclusion/exclusion adhered to NHSN criteria. Variables included demographics, clinical data and CT imaging done within three days pre-op, pathology, PATOS documentation, plan to re-operate and intra-operative cultures. Data Sources included hospital-wide surveillance data and electronic medical record.

Results: In this series rate of colon SSIs was 13.4%: with PATOS infection excluded the rate was 9.7%. Of note, overall mortality was 6.2%. Multiple factors were associated with higher SSI rates: fever, hypotension and lactate >2 (<0.001). CT imaging criteria illustrating free air, abscess, dehiscence, anastomotic leak, and inflammation as well as the number of CT findings were also significant (< 0.001). While CT findings of ischemic bowel (0.014) was significant, phlegmon was not (0.335). Pathological findings of perforation, necrosis, and number of pathological findings excluding cancer were associated with SSIs (<0.001). In addition, cancer (0.012), purulence (0.013), Inflammation (0.040) and bowel ischemia (0.004) were also associated with SSIs. Although the rate of intra-op positive cultures was higher among SSIs, 10.3% vs 7.0%, it was not significant (0.119). Plan to re-operate (<0.001) was associated with higher rates of SSI. Although PATOS documentation (p <0.001) was significant several patients had either a CT finding or pathological finding (excluding cancer alone) without documentation of PATOS, which if included as PATOS, decreased the SSI rate to 5.3%. Multivariate logistic regression was used to control for NHSN factors that increase SSIs for colon operations: diabetes, ASA, Male, Age, BMI >/=30, non-primary closure, and oncology hospitals. Only closure technique, BMI and Age were associated with SSIs.

Conclusions: Currently accepted NHSN PATOS documentation underestimates the number of patients that have features that significantly increase risk that infection was PATOS.