Study in the Journal of the American Medical Association Shows Medtronic Deep Brain Stimulation Therapy Improved Quality of Life and Motor Function in Advanced Parkinson's Disease

MINNEAPOLIS-(Business Wire)-January 6, 2009 - In the largest published, randomized, controlled study of deep brain stimulation (DBS) for Parkinson's disease, DBS was shown to be more effective than best medical therapy in improving quality of life, periods of good symptom control and motor function in patients with advanced Parkinson's disease. The study, conducted at seven Veterans Affairs and six university hospitals with participation from 255 patients, compared the benefits and risks of DBS and best medical therapy for PD patients who span a wide age range. The findings were published in the January 7, 2009 edition of the Journal of the American Medical Association.

The results from the study showed that compared to patients receiving best medical therapy after six months, patients receiving bilateral DBS of the subthalamic nucleus or globus pallidus with Medtronic Activa^® DBS Therapy plus medication had increased daily time spent in the “on” state (classified as good symptom control and unimpeded motor function), increased time spent without troubling dyskinesia (unintentional movements), increased motor function scores, increased overall quality of life scores and decreased time spent in the “off” state (classified as poor symptom control and motor impairment).

“DBS is often the treatment of choice when Parkinson's disease patients' motor function is not well-controlled with medications, but typical DBS candidates are usually younger and have fewer co-morbidities than many of the patients in this study,” said William J. Marks, Jr., M.D., associate professor of neurology, University of California, San Francisco, Director of the Parkinson's Disease Center at the San Francisco Veterans Affairs Medical Center, and a principal investigator in the study. “These data show that DBS patients consistently score higher on quality of life measures than patients receiving the best medical therapy, even for the oldest subset of patients in the study. I anticipate that the DBS benefits demonstrated in this large-scale study will be very compelling to the neurology community as physicians consider DBS as a treatment option for future patients.”

Key trial results include:

After six months, patients in the DBS group gained an average of 4.6 hours per day of "on" time, compared to no gain for the best medical therapy group. Among DBS patients, "off" time, or periods of poor symptom control and impaired motor function, decreased by 2.4 hours per day compared to no decrease in the best medical therapy group. These results were statistically significant (p ≤ 0.001).
The change in off-medication Unified Parkinson's Disease Rating Scale (UPDRS) motor scores was significantly greater in the DBS group, with patients improving 12.3 points compared to 1.7 points among those in the best medical therapy group (p ≤ 0.001).
DBS patients experienced significant improvements on seven of the eight quality of life (QOL) subscales measured by the Parkinson's Disease Questionnaire-39 (PDQ-39) compared to best medical therapy patients, who had little change in baseline on any subscale except stigma. In the single index score, which combines all eight QOL subscales, the difference between the DBS and best medical therapy groups was statistically significant (p ≤ 0.001).
When comparing the cohort of patients who were 70 years and older (25 percent of study participants) with younger patients, the benefits of DBS versus best medical therapy were similar on most measures.
Medication needs (in daily levodopa equivalents) decreased by 296 milligrams for DBS patients and increased by 15 milligrams over baseline for best medical therapy patients.

In the study, the DBS group experienced a higher risk of serious adverse events (SAEs), occurring in 40 percent of patients compared to 11 percent in the best medical therapy group. Ninety-nine percent of cases were resolved by six months. Eighty-three percent of these SAEs were attributed to the surgical procedure, device, or stimulation therapy. The most common SAE in the DBS group was surgical site infection (9.9 percent). These infections were treated with antibiotic therapy and removal of the device. Some of these patients had been re-implanted by six months of follow up. There was one death secondary to a cerebral hemorrhage within 24 hours of DBS implant. A total of 15 patients (11 percent) in the best medical therapy group experienced SAEs, including nervous system, psychiatric, and cardiac disorders; falls; other infections; and other events.

DBS was associated with small decrements in cognitive test performance at six months. During the six-month follow-up, there were significantly more events (serious and non-serious) for DBS than best medical therapy for gait disturbance, falls, depression, and dystonia.

Patients in the study were mostly male (82 percent), white (96 percent), and married (69 percent), with a mean age of 62.4 years. They had been diagnosed with PD for an average of 12 years. One-quarter were age 70 or older.

About the study

The study collected data from 255 patients from 13 U.S. centers who were randomized to best medical therapy (134 patients) or bilateral DBS (121 patients) plus medication. In the DBS group, patients were further randomized to receive stimulation with Medtronic's Kinetra® neurostimulator at either the subthalamic nucleus (60 patients) or globus pallidus (61 patients). The second phase of the study comparing these two stimulation targets remains blinded until the follow up phase is completed.

Best medical therapy patients were actively managed by movement disorder neurologists and received state-of-the-art care, including adjustments to medication dosages, frequency, and timing and non-medical therapy, including physical, occupational, and speech therapy, as needed.

Patients returned to their study sites at three and six months. Ten days prior to each visit, they were mailed motor diaries to be completed for two consecutive days prior to the visit. At three months, motor function and quality of life assessments were conducted, and the entire battery of tests was repeated at six months. The primary outcome was the baseline to six month change in time spent in the "on" state without troubling dyskinesia.

The study was conducted under FDA Investigational Device Exemption (IDE) regulations and sponsored by the Veterans Affairs (VA) Cooperative Studies Program in partnership with the National Institute of Neurological Disorders and Stroke (NINDS) and Medtronic, Inc.

About DBS Therapy

Medtronic is the pioneer of DBS therapy and it remains the only company with a commercially available DBS system currently approved by the U.S. FDA for management of symptoms of movement disorders not adequately controlled by medications, including Parkinson's disease, essential tremor, and dystonia. Medtronic's Activa^® DBS Therapy, is an adjustable, reversible, and non-drug therapy that uses a surgically implanted medical device, similar to a pacemaker, to deliver carefully controlled electrical pulses to precisely targeted areas of the brain. The stimulation can be programmed and adjusted non-invasively (without surgery) by a trained clinician to find the most appropriate type and amount of stimulation for each patient to maximize symptom control and minimize side effects.

About Parkinson's Disease

About 1.5 million Americans currently have PD, with 60,000 new cases diagnosed each year. Although symptoms vary from person to person, PD is generally characterized by two of four major features: shaking while a limb is at rest, slowness of movement, rigidity or the limbs, or poor balance. Common treatments include medication such as levodopa, which converts to dopamine in the brain. There is no known cure for PD.

About Medtronic

Medtronic, Inc. (www.medtronic.com), headquartered in Minneapolis, is the global leader in medical technology – alleviating pain, restoring health, and extending life for millions of people around the world.

Any forward-looking statements are subject to risks and uncertainties such as those described in Medtronic's Annual Report on Form 10-K for the year ended April 25, 2008. Actual results may differ materially from anticipated results.

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