Adequacy and implications of antimicrobial prophylaxis for elective surgeries in a tertiary hospital: a cross sectional and retrospective cohort study (ADEQUAP).

Background: Surgical antimicrobial prophylaxis (SAP) is essential for preventing surgical site infections (SSI) but is often improperly administered. This study assessed SAP adequacy and its association with SSI and other nosocomial infections (NI) to identify areas for improvement.

Methods: This cross-sectional and retrospective cohort study included adults undergoing elective cardiovascular, orthopaedic, colorectal surgeries and cystectomy in 2022 at a teaching hospital. SAP was considered adequate if it met all local guideline criteria: indication, drug, dose, timing of administration, redosing and duration. Associations between SAP adequacy and SSI were analyzed using generalized mixed models.

Results: Among 723 patients included (median age 68 years; 57.7% male), 714 (98.8%) received SAP. Overall multidomain adherence to SAP guidelines was 34.6%, with high compliance for regimen (92.8%), dose (97.5%), and timing (98.3%), but lower compliance for redosing (63.4%) and duration (53.9%). Regimen adequacy was significantly lower in patients with beta-lactam allergies (55.6% vs. 94.8%, p < 0.001) and in cystectomy cases compared to other procedures (41.2% vs. 94.1%, p < 0.001). Non-compliant regimens were independently associated with a higher SSI rate (adjusted OR 3.4; 95% CI: 1.8-8.3; p = 0.003), but not with non-SSI NIs. Inadequate SAP was also associated with a length of stay (LOS) exceeding 10 days (RR 4.61; p < 0.001) and higher 90-day mortality (RR 3.37; p = 0.007). Patients who developed an SSI were significantly more likely to develop additional non-SSI NIs (adjusted OR 6.1; 95% CI: 2.8-13.4; p < 0.001). Median LOS was longer in patients with SSI (16.5 vs. 7 days, p < 0.001), and SSI was also associated with increased 90-day mortality (14.7% vs. 2.7%; RR 5.42; p < 0.001).

Conclusion: Non-adherence to SAP guidelines was associated with an increased risk of SSI, prolonged LOS, and greater crude mortality. Key areas for improvement include regimen selection, appropriate redosing, and limiting SAP duration. Patients with beta-lactam allergies were specially at risk of receiving inadequate SAP. Although SAP non-compliance was not independently associated with other NIs, SSIs significantly increased their occurrence.