Risk Factors for Postoperative Infections in Cardiac Surgery Patients: A Retrospective Study

Clinical risk factors for postoperative infection in adult cardiac surgery with cardiopulmonary bypass: a retrospective study

Background

Postoperative infection remains a serious problem for patients undergoing open-heart surgery and is associated with poor prognosis and mortality.

Aim

To determine the incidence, characteristics and associated risk factors for nosocomial infections in adult cardiac surgery patients and to develop a nomogram prediction model.

Methods

Data were retrospectively collected from patients who underwent cardiac surgery with cardiopulmonary bypass (CPB) at a tertiary hospital in 2023. Patients were divided into an infected group (N = 130) and a non-infected group (N = 192). Multivariate logistic regression analysis was used to analyse the independent risk factors for healthcare-associated infections after cardiac surgery under CPB.

Results

Of the 1584 patients, 130 (8.21%) developed postoperative infections (infection group). Lower respiratory tract was the most common site of infection (N = 74, 56.9%), while Gram-negative bacteria were the predominant isolates overall (N = 81, 62.3%). Among the Gram-negative bacteria, Acinetobacter baumannii was the most frequently identified, whereas Staphylococcus aureus was the leading strain among Gram-positive bacteria. Multivariate logistic regression analysis of the 322 patients included in the study revealed that CPB duration, American Society of Anaesthesiologists score, procalcitonin concentration on the first postoperative day, monocyte:lymphocyte ratio, preinfection mechanical ventilation duration, and preinfection central venous catheterization duration were the six independent predictors of postoperative infection. The area under the receiver operating characteristic curve was 0.824 (0.778-0.870), and the model showed good predictive performance.

Conclusion

A nomogram has been developed to predict postoperative infection via commonly available data. This tool could assist clinicians in optimising the perioperative care of patients undergoing cardiac surgery with CPB, but further external validation is needed.

Procalcitonin for the diagnosis of postoperative bacterial infection after adult cardiac surgery: a systematic review and meta-analysis

BACKGROUND AND AIMS

Patients undergoing cardiac surgery are subject to infectious complications that adversely affect outcomes. Rapid identification is essential for adequate treatment. Procalcitonin (PCT) is a noninvasive blood test that could serve this purpose, however its validity in the cardiac surgery population is still debated. We therefore performed a systematic review and meta-analysis to estimate the accuracy of PCT for the diagnosis of postoperative bacterial infection after cardiac surgery.

METHODS

We included studies on adult cardiac surgery patients, providing estimates of test accuracy. Search was performed on PubMed, EmBase and WebOfScience on April 12th, 2023 and rerun on September 15th, 2023, limited to the last 10 years. Study quality was assessed with the QUADAS-2 tool. The pooled measures of performance and diagnostic accuracy, and corresponding 95% Confidence Intervals (CI), were calculated using a bivariate regression model. Due to the variation in reported thresholds, we used a multiple-thresholds within a study random effects model for meta-analysis (diagmeta R-package).

RESULTS

Eleven studies were included in the systematic review, and 10 (2984 patients) in the meta-analysis. All studies were single-center with observational design, five of which with retrospective data collection. Quality assessment highlighted various issues, mainly concerning lack of prespecified thresholds for the index test in all studies. Results of bivariate model analysis using multiple thresholds within a study identified the optimal threshold at 3 ng/mL, with a mean sensitivity of 0.67 (0.47-0.82), mean specificity of 0.73 (95% CI 0.65-0.79), and AUC of 0.75 (IC95% 0.29-0.95). Given its importance for practice, we also evaluated PCT's predictive capability. We found that positive predictive value is at most close to 50%, also with a high prevalence (30%), and the negative predictive value was always > 90% when prevalence was < 20%.

CONCLUSIONS

These results suggest that PCT may be used to help rule out infection after cardiac surgery. The optimal threshold of 3 ng/mL identified in this work should be confirmed with large, well-designed randomized trials that evaluate the test's impact on health outcomes and on the use of antibiotic therapy. PROSPERO Registration number CRD42023415773. Registered 22 April 2023.