A systematic review of the impact of subthalamic nucleus stimulation on the quality of life of patients with Parkinson's disease

The objective of this paper is to systematically and critically review the available literature on the effects of subthalamic nucleus (STN) stimulation on the quality of life (QoL) of patients with Parkinson's disease (PD). A systematic review of the literature published from 1993 to May 2013 was conducted using PubMed, Cochrane Library, MEDLINE, EBSCO host, CINAHL, and CEPS+CETD, in addition to hand searching selected periodicals and checking reference lists. The review included randomized and nonrandomized controlled trials, published in English, comparing STN stimulation with the best medical therapy on the QoL of patients with PD. The time over which QoL was evaluated ranged from baseline to 24 months. Two reviewers independently assessed the study quality and the extracted data. Of the over 273 potential studies examined, we identified seven pertinent articles published between 2002 and 2013 involving 1193 participants. Six of the seven studies were randomized controlled trials (RCTs). Almost all reported statistically significant outcomes. All the studies using QoL outcome variables included the Parkinson's Disease Questionnaire-39 (PDQ-39) (n=7) and two also used the Short Form-36 (SF-36) questionnaire (n=2). There was significant improvement in QoL (PDQ-39) up to 6 months following STN-deep brain stimulation (DBS) in three RCTs and in one nonrandomized trial and up to 12, 18, and 24 months postoperatively in one RCT each, compared with no improvement in the medical therapy groups. There was a 22% improvement in the physical summary score on the SF-36 questionnaire versus no change in the drug-only group. The quality of the trials was limited by the potential for bias associated with inadequate concealment, no reported intention-to-treat analysis, and small sample size. Moreover, there were problems in some studies with confounding factors. The main points to emerge from this review of studies on STN-DBS in patients with PD demonstrate an overall positive effect on QoL. Based on these studies, the benefits may last for 2 years. The review clearly highlights the need for well-designed, methodologically standardized outcome measurement research into the effectiveness of STN stimulation in PD. © 2013.