In our study, we enrolled 1,349 patients following elective intracranial surgery, observing a morbidity rate of postoperative stroke (PS) at 10.2%, with 6.3% attributed to hemorrhagic stroke and 4.7% to ischemic stroke. We developed nine machine learning (ML) prediction models, among which the logistic regression (LR) model demonstrated superior performance, achieving the highest Area Under the Curve (AUC) value of 0.741. Through feature importance analysis, it was identified that "preoperative plasma albumin level," "ASA classification," "preoperative routine blood hemoglobin level," "plasma albumin/globulin ratio," and "total bilirubin level" emerged as the top five significant features for predicting PS.
In this study, the efficacy of various machine learning (ML) models, including logistic regression (LR), Adaboost, Bagging, Gradient Boosting Decision Tree (GDB), Random Forest (RF), XGBoost, Gaussian Naive Bayes (NB), K-Nearest Neighbors (KNN), and Decision Tree (DT), was assessed using the test set. Our findings indicate that the LR model excelled in predicting postoperative seizures (PS), achieving an Area Under the Curve (AUC) of 0.741. Furthermore, the LR model exhibited an accuracy rate of 0.668, a sensitivity of 0.650, and a specificity of 0.670. Overall, the LR model showed a relatively high level of predictive accuracy, making it the preferred ML model. This preference was supported by its ability to highlight important features and provide some explanation for the variables' influence. For example, the LR model identified "preoperative plasma albumin level" as the most significant feature, suggesting that a lower preoperative plasma albumin level is correlated with an increased risk of PS. Similarly, the prominent rankings of "ASA classification", "preoperative routine hemoglobin level", "plasma albumin/globulin ratio" and "total bilirubin level" can be explained accordingly. Previous studies have consistently demonstrated a correlation between preoperative hemoglobin levels and the incidence and prognosis of PS. Bhupesh et al. found that women with lower preoperative plasma hemoglobin concentrations exhibited increased susceptibility to stroke [13]. Similarly, a Japanese trial revealed that low hemoglobin concentrations were linked to an increased risk of stroke in adults[14]. Moreover, a meta-analysis provided compelling evidence supporting the association between admission anemia and both ischemic and hemorrhagic stroke, as well as elevated mortality rates related to stroke [15]. Another contributing factor to the incidence of PS is the preoperative plasma albumin/globulin ratio. In a recent study, Beamer et al. observed that patients presenting with high clinical risk factors for stroke were significantly more likely to experience subsequent vascular events, which were associated with a lower blood albumin/globulin ratio. [16].
The indicators mentioned were also incorporated into our prediction model, which typically utilizes data routinely collected after admission, underscoring the model's practical feasibility and generalizability within a hospital setting. The predictive factors identified in our model align with the risk factors highlighted in several prior studies, reinforcing its validity. The logistic regression algorithm employed in this study offers distinct advantages over traditional statistical methods, including a transparent model structure and a probability derivation that is robust and open to scrutiny. The parameters within the model elucidate the impact of each feature on the outcome, providing high interpretability. Moreover, the model supports online learning, enabling easy parameter updates without the need for retraining the entire model. Consequently, this model not only integrates the predictive efficiency of key factors but also boasts commendable interpretability.
Currently, there is a paucity of research on PS in the field of neurosurgery. Nonetheless, among the sparse machine learning (ML) studies available, one conducted by Zhang et al. stands out. They discovered that the XGBoost model displayed the highest Area Under the Curve (AUC) of 0.78 for predicting PS in elderly patients. The study identified hypertension, cancer, congestive heart failure, chronic lung disease, and peripheral vascular disease as the top five predictors. [17]. It is important to highlight that the study did not place any restrictions on the types of surgical procedures evaluated, potentially encompassing high-risk interventions for stroke, such as cardiac macrovascular surgery. Additionally, another study identified advanced age, pre-existing valvular heart disease, previous stroke, emergency surgery, and postoperative hypotension as independent risk factors for postoperative stroke (PS). [18]. Patients necessitating emergency surgery exhibit a heightened vulnerability to postoperative complications, including postoperative seizures (PS). Consequently, these patients were excluded from the aforementioned studies to ensure a more focused and controlled analysis of risk factors and outcomes.
The incidence of postoperative stroke (PS) can be linked to a variety of pathologic and physiologic mechanisms. The administration of anesthesia and the execution of the surgical procedure provoke a systemic inflammatory response, leading to alterations in the concentrations of inflammatory mediators and the coagulation status of the blood. These alterations enhance the risk of perioperative thrombosis and intravascular plaque instability, subsequently elevating the probability of stroke in perioperative patients. [19, 20].
Our research represents the inaugural effort to construct a predictive model for postoperative stroke (PS) using a machine learning-based logistic regression (LR) algorithm, specifically designed for patients undergoing elective intracranial surgery. This model is distinguished by its explainability through feature importance analysis. Moreover, by statistically addressing the issue of unbalanced data, we have developed a practical predictive tool that enables clinicians to fine-tune clinical therapy. Nonetheless, our study is not without its limitations. Firstly, the presence of missing values in the original dataset could compromise the stability of our predictive ML model. Secondly, the study's sample size was relatively small, necessitating a larger, multicenter sample to further substantiate the predictive model's validity. Thirdly, this predictive model requires an independent dataset to assess its extrapolation and generalization capabilities accurately. Lastly, anesthesia-related incidents such as persistent intraoperative hypotension/hypertension during the perianesthetic period were not included due to insufficient data availability. Future endeavors will focus on gathering comprehensive external validation datasets to enhance the validity of this model.