Subthalamic nucleus deep brain stimulation (STN-DBS) provides lasting benefits for patients with moderate-to-advanced Parkinson’s disease (PD), with sustained improvements in movement and quality of life, new long-term data from the INTREPID trial showed.

“Although STN-DBS outcomes declined slightly, possibly due to the progressive nature of the disease, patients with PD sustained significant improvement in motor and activities of daily living scores, along with a stable reduction in anti-parkinsonian medication over the 5-year follow-up period,” the authors wrote.

The 5-year outcomes were published online on September 15 in JAMA Neurology.

Long-Term Motor Benefits

The randomized, double-blind, sham-controlled trial was conducted at 23 movement disorder centers across the US. Study participants had bilateral idiopathic PD with more than 5 years of motor symptoms, more than 6 hours a day of poor motor function, modified Hoehn and Yahr scores higher than 2, a Unified Parkinson’s Disease Rating Scale (UPDRS-III) score of 30 or higher off medication, and 33% or greater improvement on UPDRS-III on medication.

A total of 191 patients (mean age, 60 years; 73% men) received bilateral active STN-DBS or subtherapeutic stimulation using the Vercise DBS system (Boston Scientific) for 12 weeks.

After 12 weeks, all participants transitioned into active, open-label treatment for up to 5 years. A total of 137 (72%) patients completed the 5-year follow-up.

Motor function without medication as measured by UPDRS-III improved from a mean of 42.8 at baseline to 21.1 at 1 year (51% improvement; P < .001) and 27.6 at 5 years (36% improvement from baseline; P < .001), the researchers reported.

Activities of daily living scores off medication improved by 41% at 1 year (from mean of 20.6 to 12.4; P < .001) and 22% at 5 years (mean score, 16.4; P < .001). Dyskinesia scores dropped by 75% at 1 year and remained 70% lower at 5 years.

Medication use also declined. Levodopa equivalent daily dose decreased by 28% at 1 year and stayed at that level through year 5, reducing drug-related complications while maintaining symptom control.

Overall, the 5-year results mirror results reported at 2 years, as previously reported by the Medscape Medical News.

The most common serious adverse event was infection, occurring in nine participants, most requiring surgical intervention. Ten deaths occurred during the study; none were attributed to DBS. Overall, the procedure was deemed safe and consistent with prior reports.

Patient satisfaction with treatment, assessed over the 5-year period, was high at 94%.

“Collectively, our results illustrate that while the degree of improvement in UPDRS-III scores may diminish over time (probably due to disease regression), STN-DBS continues to provide significant long-term motor benefits for PD patients,” the researchers concluded.

“This therapy not only enhances quality of life in the short term but also maintains its efficacy in managing motor symptoms and reduces the need for anti-parkinsonian medication and dyskinesia while improving ADLs [activities of daily living] over many years,” they added.

Boston Scientific funded the INTREPID trial and provided the DBS system used. Philip A. Starr reported receiving personal fees from Boston Scientific during the conduct of the study, grants from Boston Scientific, and fellowship funding from Medtronic outside the submitted work, and holding a patent relevant to DBS.