SALT LAKE CITY — Deep brain stimulation surgery proved far more effective than medical therapy in a large, randomized Parkinson's disease trial in the United Kingdom, adding to mounting evidence that surgery is the best option for many patients with advanced disease.
The PD SURG trial randomized 366 patients with advanced disease to receive subthalamic nucleus deep brain stimulation (183 patients) or medical therapy (also 183) at centers located throughout the United Kingdom.
Interim results were reported at the annual meeting of the American Neurological Association by Dr. Adrian Williams, professor of clinical neurology at Queen Elizabeth Hospital, Birmingham (England) and coordinator of the trial.
“For 25%–30% of the patients, there was a very, very significant improvement in quality of life,” he said in an interview at the meeting.
Patients enrolled in the trial had quite extensive disease, with 11 years' mean disease duration. Their main reasons for considering surgery were dyskinesia and severe off-periods, said Dr. Williams.
At 1 year, overall PDQ-39 (Parkinson's Disease Questionnaire) scores were unchanged in patients receiving medication alone, but improved 5.8 points on the 156-point scale in those who received surgery, a highly significant difference (P = .0002).
Within this scale, activities of daily living showed a particularly pronounced improvement in patients who underwent surgery, improving, on average 12 points among surgical patients but less than 1 point among patients receiving medical therapy, Dr. Williams noted.
A similarly significant, 8.5-point difference in scores on the 0- to 176-point Unified Parkinson's Disease Rating Scale (UPDRS) favored patients in the surgical arm.
A subset of patients had a dramatic response to surgery, Dr. Williams said.
Nearly a quarter of patients who underwent surgery showed 16-point or greater reductions in their overall PDQ-39 scores, compared with 2% of patients receiving medical therapy. These patients, he said, “tended to be a bit younger, with slightly more aggressive disease.”
Their motor involvement tended to be profound at the onset of the study.
As in previous studies, some patients failed to show much improvement following surgery, suggesting the need for identifying clear predictive factors that can tailor interventions to those most likely to benefit, Dr. Williams said.
Surgery was not without risks, with 1% of patients dying and 1% suffering strokes in the surgery arm.
The cost of surgery was about double that of a years' worth of drug therapy, but the magnitude of improvement of some patients would certainly justify the cost.
Dr. Williams stressed the “real world” design of the trial, which attempted true randomization at regional centers rather than “cherry picking by patient or by surgeon.” For ethical reasons, patients assigned to the medication arm of the study were offered surgery after 1 year.
The PD SURG trial was supported by the U.K. Medical Research Council and the Parkinson's Disease Society.
The study results parallel findings in two smaller, National Institutes of Health- sponsored trials, one performed with the Department of Veterans Affairs and one coordinated by researchers at the University of Florida, Gainesville.