Objective: To investigate if patients with Parkinson’s disease (PD) undergoing subthalamic stimulation (STN-DBS) can be clustered in different subtypes based on demographic, motor and non-motor symptoms (NMS) and if these clusters help to identify patients who do not experience postoperative quality of life (QoL) improvement.

Background: STN-DBS is an established treatment in advanced PD improving QoL, motor symptoms, and NMS. However, the clinical presentation of PD is highly heterogeneous and considerable inter-individual variability has been observed for postoperative QoL outcome.

Method: To identify subtypes, we conducted K-means clustering analysis of 22 variables in a prospective, observational, international, multicenter study. Variables included baseline z-scores of disease duration, age at baseline, NMSScale (NMSS) total and domain scores, Hospital Anxiety and Depression Scale (HADS)-anxiety and depression subscores, Scales for Outcomes in PD (SCOPA)-motor examination and subscores, and percentage of motor response in levodopa challenge test. We used Kruskal-Wallis-test (K-W) to analyze differences of PDQuestionnaire (PDQ)-8 changes at 6-month follow-up between subtypes. In a second step, discriminant analysis was applied to identify key features that distinguish subtypes at baseline.

Results: 211 patients were categorized in three clusters. Their postoperative PDQ-8 outcomes differed significantly (P=0.021). Discriminant analysis reduced the number of variables needed for subtyping to seven (disease duration since diagnosis, NMSS total, NMSS mood/apathy, and perceptual problems/hallucinations domains, NMSS item on excessive sweating, HADS-depression, SCOPA-axial symptoms subscore). These variables categorized 91.5% of patients correctly to previously identified clusters. Finally, K-W confirmed group differences of PDQ-8 changes (P=0.007).

Conclusion: Clustering and discriminant analysis applied on a big dataset including 211 patients undergoing STN-DBS identified a short list of seven variables which stratified for differences of QoL outcomes. This approach can help to better understand our patients, define their differences, and provide them with more useful treatment options by tailoring the services to meet the specific needs of the subgroup members in line with the concept of personalized medicine.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/subtyping-parkinsons-disease-quality-of-life-changes-after-subthalamic-stimulation-depend-on-nonmotor-and-motor-symptoms/