A new study published in JAMA Network Open Neurology reports a five-year follow-up of patients with Parkinson’s disease (PD) treated with either medication alone or deep brain stimulation (DBS) of the hypothalamic nuclei (STN).
Study: Neurostimulation for advanced Parkinson’s disease and quality of life at 5 years: a non-randomized controlled trial. Image credit: Pavlova Yulia / Shutterstock.com
What is DBS?
PD is one of the most common and tragically disabling neurological conditions in older adults. DBS-STN has been shown to help patients suffering from advanced stages of PD. However, there is little data to support the long-term effectiveness of this treatment.
Previous research revealed that DBS-STN helped PD patients regain some of their quality of life (QOL) and alleviated some movement-related and non-movement-related symptoms. The effects of this treatment on motor symptoms have been demonstrated in long-term studies with a follow-up of more than five years. However, these studies did not report similar benefits related to improved quality of life.
This led to more recent meta-analyses of the literature for patients with DBS-STN, who claimed better quality of life for up to three years after surgery and then returned to baseline at five years. However, all PD patients experience a declining quality of life in standard medical care.
About the study
The current study compared quality of life between patients treated with either standard medication (MED) or DBS-STN for three or more years.
The hypothesis was that at five years, patients with advanced PD would not show a significant change in their quality of life compared to the deterioration seen in patients in MED. This would lead to better outcomes with DBS-STN, as evidenced by reduced need for medication or improved motor symptoms, as well as higher QOL. The researchers also investigated relationships between impaired quality of life and other outcomes.
The current observational study involved multiple centers as part of the ongoing Non-Motor International Longitudinal Study (NILS) prospective study. A total of 108 patients participated in the study, 46 and 62 of whom were treated with MED and DBS-STN, respectively.
Both groups were comparable in terms of advanced motor and non-motor symptoms, particularly dyskinesia, tremor resistance to medication, and on/off states. Both patients were prescribed oral or transdermal medications.
The median duration of PD in the study cohort was 7.7 years. However, the DBS-STN group had a longer median duration. At baseline, quality of life in the DBS-STN group was lower and their motor symptoms were worse than those in the MED group.
What did the study show?
A 50% reduction in quality of life was observed in the MED group over five years, while a steady trend was observed in the DBS group. The difference between QOL scores at baseline was 6.6 points favoring the DBS group.
In the MED group, total mobility scores decreased by 4.5 points. In comparison, DBS-STN resulted in an initial improvement in mobility scores, which eventually declined and returned to baseline.
The greatest improvement was in mobility at five years in the DBS-STN group compared with the MED group, with the total mobility score being one unit higher in the former.
The reduction in the overall mobility score in the MED group was attributed to deterioration in activities of daily living (ADL) scores by 25% and motor complications by over 27%. In contrast, the DBS group showed a 47% improvement in motor symptoms.
Quality of life remained higher in the DBS-STN group, mainly due to increased mobility. In addition, this group enjoyed better support from their social contacts, were better able to perform their ADL, had less discomfort and felt less stigma. This highlights the advantages of using DBS in terms of better engine response.
However, the MED group demonstrated better communication ability, as expected from previous studies that revealed that speech intelligibility suffered over time with DBS-STN.
The DBS group had a 62% reduction in their levodopa equivalent daily dose (LEDD) requirements. In comparison, MED Group recorded a 17% increase for LEDDs.
Total electrical energy delivered (TEED) increased by 90% from the one-year to five-year follow-up time point.
Adverse events (AEs) occurred at a significantly high rate in the study, as reported in previous studies, reflecting the need for proper patient assessment of risk-benefit scores prior to surgery. None of the reported AEs were life-threatening, and a third were related to the device or surgery. Psychiatric and neurological AEs were also frequently reported.
What are the consequences;
The study findings demonstrate that DBS-STN improves the quality of life in patients with advanced PD, mainly by promoting their mobility. This clinically significant difference was not observed in DBS patients treated for very early PD without motor complications or dyskinesia.
Higher quality of life was associated with better ADL scores, although not for other symptoms. Therefore, ADL should be discussed when investigating the long-term outcomes of DBS-STN in PD patients. Furthermore, further research is needed to identify preoperative risk factors for poor quality of life outcome in these patients.
Motor symptoms and PD medication requirements were tracked for five years for the first time in this study. Similar to previous studies, the researchers observed that motor symptoms improved significantly at this time point in the DBS group but only at one year in the MED group.
The one-year improvement in the MED group was attributed to the optimization of medication protocols at the start of the study. However, this was followed by dyskinesia and greater variability in motor symptoms until return to baseline. This may be a result of disease progression or complications from long-term dopamine agonist therapy.
The association between changes in quality of life and ADL highlights the relative importance of ADL outcomes for long-term DBS evaluations.“
Improvement in quality of life was limited to advanced PD cases and motor symptoms but not communication outcomes. Overall, the findings of the study should help advise which patients are suitable for DBS-STN and how to follow up postoperatively.
Journal Reference:
- Jost, ST, Aloui, S., Evans, J., et al. (2024). Neurostimulation for advanced Parkinson’s disease and quality of life at 5 years: a non-randomized controlled trial. JAMA Network Open Neurology. doi:10.1001/jamanetworkopen.2023.52177.
