Age, emotional burden and deep brain stimulation electrode location shape Parkinson's disease quality of life

Postoperative quality-of-life (QoL) outcomes after subthalamic deep brain stimulation in Parkinson's disease vary widely. Previous studies based on PDQ-39 summary scores have reported opposing relationships between baseline and postoperative QoL, reflecting analytic variability, measurement noise, and limited feature scope. To address these inconsistencies, we analyzed 130 patients using an explainable random-forest classifier with SHAP analysis trained to predict QoL changes exceeding minimal clinically important difference thresholds. Baseline variables included PDQ-39 subscores, along with demographic, motor, cognitive, and affective measures, and electrode coordinates derived from imaging. Predictors of QoL improvement included younger age, greater preoperative disease-related emotional burden, and electrode placement at the motor-associative transition in the right subthalamic nucleus. The model achieved an area under the curve of 0.70 on the held-out test set, with balanced sensitivity and specificity. Identifying interpretable cut-offs for age, emotional burden and electrode location supports individualized counseling and treatment planning, advancing outcome prediction in neuromodulation.