Bilateral subthalamic nucleus deep brain stimulation produced durable improvements in motor function, activities of daily living, and dyskinesia in patients with moderate to advanced Parkinson disease, according to 5-year trial data from the INTREPID trial.
In the medication-off, stimulation-on condition improved by 51% at year 1 and remained 36% at year 5 compared with baseline. Activities of daily living improved by 40% at year 1 and 20% at year 5. Dyskinesia scores decreased by 75% at year 1 and 70% at year 5. The levodopa equivalent daily dose declined 28% at year 1 and remained 28% lower at year 5. Quality-of-life scores improved by 32% at year 1, but this benefit declined over time, with only a non-significant 5% improvement remaining at year 5.
Adverse events were frequent but largely nonserious. Across 182 patients, 1,136 events were reported, most often dyskinesia, falls, tremor, and implant-site complications. Infections were the most frequent serious adverse event, reported in 9 patients. Ten deaths occurred during the study period, none related to the intervention. Despite these events, 94% of patients reported satisfaction with treatment at 5 years.
The study enrolled 313 patients across 23 US centers; 193 received STN-DBS implants and 137 completed the 5-year follow-up. Mean age was 60 years, and 73% of patients were men. Eligibility required idiopathic Parkinson disease of at least 5 years’ duration, more than 6 hours per day of poor motor function, and a Unified Parkinson’s Disease Rating Scale part III (UPDRS-III) score of 30 or greater in the medication-off state, with at least a 33% improvement on medication.
Limitations included the open-label design after the initial 12-week blinded phase, diary-based “good on time” data limited to year 1, and advances in DBS technology since study initiation. Researchers noted that diminishing benefits likely reflect disease progression.
“As DBS procedures continue to advance in safety and consistency of benefit, it is likely more patients will consider DBS earlier in the course of their disease,” said senior study author Jerrold L. Vitek, MD, PhD, University of Minnesota and colleagues.
Full disclosures can be found in the study.
Source: JAMA Neurology
