How to Calculate the Risk of Sternal Instability

Objectives: The calculation of the individual patient's risk of sternal instability is useful for the planning of the surgical procedure and for the patient's preoperative informed consent. Patients having an excessive risk may be scheduled for alternative access routes or additional techniques for sternal osteosynthesis. The aim of this study was both to analyze the risk factors for sternal instability and to create a risk score based on the results of this analysis.

Methods: Data of patients scheduled for all-type cardiovascular operations with sternotomy between 2008 and 2017 were analyzed for clinical apparent non-infective sternal dehiscence during the hospital stay. All variables from the logistic regression univariable analysis with a p-value of <0.1 were entered into a backward stepwise multivariable logistic regression analysis. Odds ratio (OR), with 95% confidence interval (CI), was calculated for each variable. Variables were eligible for inclusion at a p-value <0.1. Each of the risk factors was weighted according to its regression coefficient. A scoring system was implemented to weight the individual risk factors resulting in a personal risk score predicting sternal instability.

Result: Sternal dehiscence without infection occurred in 2.5% of seven thousand one hundred patients. The model showed good sensitivity and specificity (area under the receiver-operating characteristic curve, AUC: 0.76) and several predictors of sternal instability were evaluated. Multivariable logistic regression showed the highest odds ratios (ORs) for obesity (BMI >35 kg/m²; OR: 4.23, [CI: 2.4–7.3], p < 0.001), insulin-dependent diabetes mellitus (IDDM; OR: 2.2, CI [1.5–3.2], p = 0.01), and smoking (OR: 2.03, [CI: 1.3–3.08], p = 0.001). After weighting the probability of sternum dehiscence with each factor, a risk score model was proposed with a scale up to 5 points. This resulted in a risk score of up to 18 points, with an estimated risk for sternum complications of up to 74%.

Conclusion: A weighted scoring system based on individual risk factors was specifically created to predict noninfective sternal dehiscence. High-scoring patients should receive additive closure techniques. Further prospective studies are needed for validation.

No conflict of interest has been declared by the author(s).

Publication History

Article published online:
19 February 2021