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Deep brain stimulation shows greater efficacy than best medical care in advanced PD; associated with higher adverse event rates, trial data show

Wednesday, January 21 2009 | Comments
Evidence Grade 1 What's This?
Relative to optimal medical therapy, deep brain stimulation (DBS) extends "on" time and improves motor function and quality of life (QOL) in patients with advanced Parkinson's disease (PD), data from a randomized trial indicate. However, the study findings also reveal a higher rate of adverse events with the surgical intervention.

Researchers randomized 255 patients with PD (Hoehn and Yahr stage >=2 when off medication) to receive best medical therapy managed by movement disorder neurologists (n=134), or DBS of the subthalamic nucleus (n=60) or globus pallidus (n=61).

The intent-to-treat analysis of the primary outcome measure showed that after 6 months of treatment, the DBS group had gained an average of 4.6 hours per day of on time without troubling dyskinesias, compared with 0 hours per day gained in the medical therapy group (between-group mean difference, 4.5 hr/day; 95% CI, 3.7-5.4 hr/d; P<.001).

Results also showed significantly greater improvements with DBS in Unified Parkinson's Disease Rating Scale off-medication motor scores, activities of daily living scores, and complications of therapy scores (P<.001 for all comparisons). In addition, DBS was associated with significantly greater improvements in QOL (P<.001 for between-group difference in overall QOL score).

There were small but statistically significant declines in some cognitive test scores with DBS compared with best medical therapy. Between-group differences were significant for working memory (P=.005), processing speed (P=.006), phonemic fluency (P<.001), and delayed recall (P=.03).

A total of 659 moderate or severe adverse events were documented in the DBS group, compared with 236 such events in the best-medical-therapy group. DBS was associated with significantly higher rates of falls (P<.01), gait disturbances (P=.03), depression (P=.03), and dystonia (P<.01). Other adverse events with DBS included surgical site infection (9.9%) and surgical site pain (9.0%).

The most common neurobehavioral adverse events were depression, confusional state, and anxiety, all of which were more common with DBS than with best medical therapy.

A total 82 serious adverse events (SAEs) occurred in 49 of the DBS-treated patients (40%), including 39 events related to the surgical procedure and 1 death following a cerebral hemorrhage 24 hours after lead implantation. Significantly fewer patients experienced an SAE in the best-medical-therapy group (19 events in 15 patients; 11%; P<.001). The overall incidence risk of experiencing an SAE was 3.8 times higher with DBS than with best medical therapy (95% CI, 2.3-6.3).

In general, the authors noted, the benefits of DBS relative to best medical therapy were similar in younger (aged <70 years) and older patients. However, they added, while the incidence of SAEs did not differ by age, adverse events in general were more common in the older age group.

"The clinical significance of the adverse events and minor neurocognitive changes observed in patients in the DBS group and, more importantly, whether patients who undergo DBS view improvement in motor function and QOL as outweighing adverse events, remain to be explored," the investigators concluded. (Weaver FM, et al. JAMA 2009;301:63-73.)

Medtronic Neuromodulation provided financial support for this study.

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