The tool may help select those who will benefit the most from the procedure, guiding patients and physicians in the decision-making process.
The study, “Quality of Life Improvement Following Deep Brain Parkinson’s Disease: Development of a Prognostic Model,” was published in the journal Neurosurgery.
Deep brain stimulation (DBS), an established treatment for Parkinson’s disease, is a neurosurgical procedure that involves implanting a medical device called a neurostimulator in the brain, which will send electrical impulses to specific brain regions.
While several studies have discussed the potential benefits of using deep brain stimulation, others have reported DBS-associated complications, making it hard for patients to decide whether they should undergo the procedure.
One of the most important markers of success after a surgical procedure is the evaluation of a patient’s quality of life (QoL). Researchers have become very interested in determining the factors that can best predict QoL improvements after DBS surgery.
Investigators attempted to develop a model that can help predict improvement in QoL after surgery for deep brain stimulation.
Specifically, they made use of preoperative patient characteristics and imaging data that would be available in most centers that regularly perform deep brain stimulation.
QoL was measured using the Parkinson’s Disease Questionnaire-39 (PDQ-39). Then, potential predictive factors — such as patient demographics, clinical presentation, imaging scans, and motor and psychological testing — were analyzed for their impact on QoL scores post-surgery.
Among the 67 patients in the study, 36 (53.7%) experienced an improved quality of life following surgery. Researchers discovered that there were five variables that significantly contributed to the QoL outcome.
The first was the number of years since the onset of symptoms. An analysis showed that for every additional year since symptoms onset, patients demonstrated an 11% greater chance of improvement in QoL.
The second variable was bilateral DBS implantation. Essentially, patients who underwent deep brain stimulation implants in both hemispheres of the brain were six times more likely to have an improvement in QoL compared to those who only underwent right-sided DBS.
The third was the UPDRS-III total score, which assesses the motor signs of Parkinson’s disease. Researchers showed that for every extra 1% “on” vs. “off” medication change in UPDRS-III total score, the odds of quality of life improvement increased by 4.5%.
“On” in UPDRS-III refers to patients who are receiving medication and have a good response, while “off” refers to times when patients have a poor response in spite of taking medications. Therefore, patients who are responsive to medication are more likely to experience an improvement in QoL after deep brain stimulation.
The fourth variable was the levodopa-equivalent daily dose. Results showed that for every every additional 100 units of levodopa-equivalent daily dose that a patient was prescribed preoperatively, the improvement in QoL increased by 12.4%
Finally, for every one-point increase in the preoperative PDQ-39 score — which indicates worse QoL — patients experienced a 7.3% increase in odds of improvement after DBS.
To develop the predictive model, researchers used three of these factors: change in PDQ-39, percent change in UPRS-III, and years since symptom onset. These three factors were able to collectively predict improvement in QoL after DBS with an 81% accuracy.
“Our data may serve as the foundation to further refine a clinically relevant prognostic tool that would assist the decision-making process for clinicians and DBS multidisciplinary teams assessing patient candidacy for surgery,” investigators wrote.