Background Cerebral hyperperfusion syndrome (CHS) is a common complication after revascularization surgery for moyamoya disease (MMD). Previous studies on its risk factors have yielded controversial results.

Objective To screen the risk factors and construct a nomogram model for predicting the risk of CHS after combined bypass surgery in adult patients with MMD.

Methods A retrospective analysis was conducted on 391 adult patients with MMD who underwent combined bypass surgery in Neurosurgery Department of Tianyou Hospital affiliated to Tongji University from September 2020 to December 2023. The dataset was divided into training and validation datasets according to different time periods. Based on whether CHS occurred after surgery, the training set data was divided into CHS group and non-CHS group. A comparison and analysis were conducted to identify the risk factors for the development of CHS in adult patients with MMD after surgery. Univariate and multivariate Logistic regression analysis were performed to screen the best predictive variables and construct a clinical prediction model. Utilizing the bootstrap method and time series data for internal validation of the model, we assessed the model through the Hosmer-Lemeshow goodness-of-fit test, calibration curves and the receiver operating characteristic (ROC) curve.

Results Multivariable regression results showed that age, surgical side and preoperative mean arterial pressure were significant risk factors, thus leading to the construction of a nomogram based on these variables. Validation using the bootstrap method demonstrated strong consistency between the predicted probabilities and the actual occurrence probabilities (χ²=14.793, P=0.063), with the area under the ROC curve (AUC) of the model being 0.956 (95% CI: 0.915 - 0.997). Further validation of the model using other time series dataset revealed no statistically significant predictive bias between the predicted probabilities and actual observed values (χ²=8.593, P=0.378), with the AUC being 0.924 (95% CI: 0.854 - 0.995). Both validation methods indicated that the predictive model exhibited strong predictive performance.

Conclusion Age, side of surgery and preoperative MAP are the main predictive factors for CHS determination after combined bypass surgery in adult patients with MMD, among which preoperative MAP is a controllable risk factor. The nomogram prediction model constructed through the risk factors has high predictive value.