The Barts Surgical Infection Risk tool (B-SIR): external validation and comparison with existing tools to predict surgical site infection after cardiac surgery

Rosalie Magboo; Jackie Cooper; Alex Shipolini; George Krasopoulous; Bilal H Kirmani; Enoch Akowuah; Heather Byers; Julie Sanders

doi:10.1016/j.jhin.2024.11.014

The Barts Surgical Infection Risk tool (B-SIR): external validation and comparison with existing tools to predict surgical site infection after cardiac surgery

J Hosp Infect. 2024 Nov 30:S0195-6701(24)00395-5. doi: 10.1016/j.jhin.2024.11.014. Online ahead of print.

Authors

Rosalie Magboo¹, Jackie Cooper², Alex Shipolini³, George Krasopoulous⁴, Bilal H Kirmani⁵, Enoch Akowuah⁶, Heather Byers³, Julie Sanders⁷

Affiliations

¹ St Bartholomew's Hospital, Barts NHS Trust, London, UK; William Harvey Research Institute, Queen Mary University of London, London, UK. Electronic address: Rosalie.renamagboo@nhs.net.
² William Harvey Research Institute, Queen Mary University of London, London, UK.
³ St Bartholomew's Hospital, Barts NHS Trust, London, UK.
⁴ Oxford University Hospital NHS Foundation Trust, Oxford, UK.
⁵ Liverpool Heart and Chest Hospital NHS Foundation Trust, Liverpool, UK.
⁶ James Cook University Hospital, Middlesbrough, UK.
⁷ St Bartholomew's Hospital, Barts NHS Trust, London, UK; William Harvey Research Institute, Queen Mary University of London, London, UK.

PMID: 39622473
DOI: 10.1016/j.jhin.2024.11.014

Abstract

Objective: We previously developed and internally validated the Barts Surgical Infection Risk (B-SIR). We sought to explore the external validity of the B-SIR tool and compare with the Australian Clinical Risk Index (ACRI) and Brompton and Harefield Infection Score (BHIS).

Study design and setting: This multicentre retrospective analysis of prospectively collected local data included adult (≥18years) patients undergoing cardiac surgery between January 2018 and December 2019. Pre-pandemic data was used as a reflection of standard practice. Area under the curve (AUC) was used to validate and compare the predictive power of the scores and calibration was assessed using Hosmer-Lemeshow test and calibration plots.

Results: From three centres, 6,022 patients were included in the complete case analysis. The mean age was 66 years, 75% were men and 3.19% developed SSI. The B-SIR has an AUC of 0.686 (95% CI: 0.649 to 0.723) similar to the developmental study (AUC=0.682; 95% CI: 0.652 to 0.713). This is significantly higher than BHIS AUC=0.610 (95% CI: 0.045 to 0.109; p<0.001) and ACRI AUC=0.614 (95% CI: 0.041 to 0.103; p<0.001). After re-calibration using a correction factor, the B-SIR model gave accurate risk predictions (Hosmer-Lemeshow test p=0.423). Multiple imputation result (AUC=0.676; 95%CI: 0.639 to 0.712) is similar to development data and is higher than ACRI and BHIS.

Conclusion: External B-SIR validation indicates B-SIR predicts SSI after cardiac surgery better than ACRI and BHIS risk tools. This suggests B-SIR could be useful to use routinely in practice.

Keywords: cardiac surgery; external validation; prediction model; risk assessment; risk tool; surgical site infection.