Development and Internal Validation of a Simplified Clinical Risk Score for Systemic Complications After Spine Surgery Using a Nationwide Japanese Registry: JOANR/JSSR-DB.

Introduction: We developed a simplified scoring system (JSSR-DB RC3S) to predict systemic complications after spine surgery using data from the nationwide Japanese Society for Spine Surgery and Related Research Database (JSSR-DB). Methods: This retrospective cohort study included 8,930 spine surgery cases registered between January and March 2024. The target outcome was systemic complications occurring intraoperatively or within 30 days postoperatively. Candidate preoperative variables were screened using least absolute shrinkage and selection operator logistic regression with 5-fold cross-validation, and the five dominant predictors were used to construct the JSSR-DB RC3S. Integer points were assigned using a zero-start scoring approach, followed by score-based recalibration. Internal validation used out-of-fold predictions from 5-fold cross-validation. Results: The incidence rate of systemic complications was 1.7% (156/8,930). The five selected predictors were age, performance status, emergency surgery, degenerative disease, and spinal trauma. The final score ranged from 0 to 22 points. Observed incidence rates increased from 0.23% in the low-risk group (0-2 points) to 6.67% in the high-risk group (14-22 points). The model performance was acceptable, with an area under the curve of 0.740, observed-to-expected ratio of 0.997, and Brier score of 0.0167. Conclusions: The JSSR-DB RC3S is a transparent, clinically interpretable, simplified score for predicting systemic complications after spine surgery, derived from Japanese nationwide registry data. It may support perioperative risk communication in daily practice, and may serve as an introductory implementation of the broader JSSR-DB risk calculator framework.