A meta-analysis of studies of deep brain stimulation for persons with Parkinson's disease

Weaver FM, Follett K, Hur K, Stern M. A meta-analysis of studies of deep brain stimulation for persons with Parkinson's disease. Paper presented at: VA HSR&D National Meeting; 2003 Feb 1; Washington, DC.

Objectives: To compare the effectiveness of bilateral deep brain stimulation (DBS) of the subthalamic nucleus (STN) and globus pallidus interna (GPi) on motor function in patients with Parkinson's disease (PD). Methods: A meta-analysis was performed of relevant clinical studies evaluating bilateral STN or Gpi on patient motor function. Thirteen studies of STN and 8 studies of Gpi were identified with follow-up data on motor function. None of the trials were randomized. All studies had pre and post intervention data. Outcomes collected at or close to 6 months post-intervention were examined. Separate analyses of the STN and Gpi studies were conducted using the motor function subscale of the Unified Parkinson's Disease Rating Scale (UPDRS). The outcome of interest was motor function when the patient was receiving stimulation but off medications. Results: The 13 STN studies included 163 subjects. The mean + sd for the motor score at baseline was 55.7 + 13.8 and at six months post-surgery it was 21.0 + 12.3. On average, subjects demonstrated a 62.3% improvement in UPDRS motor score. There were 46 patients included in the 8 Gpi studies. Baseline motor scores averaged 55.7 + 10.3. At follow-up the mean score was 43.4 + 12.1, representing a 38.2% improvement in motor score after surgery. Conclusions: These data suggest that DBS in patients with PD results in improved motor functioning at both sites. However, these results should be interpreted cautiously because they are based on non-randomized study designs with small sample sizes and limited follow-up. These limitations warrant a large randomized trial of DBS at both anatomical sites, including a comparison of DBS to best medical therapy. Impact: One of the greatest unmet therapeutic needs in PD is the effective treatment of motor complications (motor fluctuations and dyskinesias), a virtually universal consequence of longstanding PD and medication therapy. DBS substantially improves function in PD patients experiencing motor complications. A well controlled, large, randomized clinical trial of DBS in PD will determine the most appropriate site of stimulation, the best candidates for the procedure and the comparative value of surgery versus the best medical therapies available.