"Although levodopa remains the foundation of Parkinson's disease therapy, the medical community has long recognized that its use can be limited due to the inability to control Parkinson's disease symptoms over time," said investigator Robert A. Hauser, M.D., M.B.A., director of the Parkinson's Disease and Movement Disorders Center of the University of South Florida in Tampa and member of an international consortium of researchers known as the End-of-Dose Wearing Off (EODWO) Working Group. "However, this study shows that end-of-dose 'wearing off' may be a bigger problem for Parkinson's disease patients than physicians and other members of the health care community realize."
Within one to two years, almost 50 percent of PD patients receiving levodopa therapy begin to notice that their medication lasts for shorter periods, causing symptoms to re-emerge before the next dose. This phenomenon is known as "wearing off." Eventually, the effect of a levodopa dose may decrease from eight hours when patients begin levodopa therapy to only one to two hours. "Wearing off" is associated with the re-emergence of motor symptoms (e.g. tremor and problems with balance), non-motor symptoms (e.g. anxiety, fatigue, mood changes, and restlessness), and autonomic nervous system dysfunction (e.g. sweating and hypersalivation).
"To date, the frequency of end-of-dose 'wearing off' in a general neurology practice is unknown, and no specific tools exist to aid clinical diagnoses of its signs and symptoms," said Dr. Hauser. "Because there are new medications available that can help to improve symptom control throughout more of the day, it is important for physicians to have a simple way to identify these symptoms."
A group of 10 international Movement Disorder specialists (the End-of-Dose Wearing Off Working Group) collaborated to assess prospectively whether or not a specifically designed patient questionnaire can identify the same or more subjects suffering from end-of-dose "wearing off" than a clinical assessment. The blinded study used the AliProject, a web-enabled database of patients treated at participating Parkinson's disease research centers in the United States. The clinical database was developed by the Muhammed Ali Parkinson Research Center.
Three hundred patients diagnosed with Parkinson's disease participated in the study. All were age 30 or older, and had Parkinson's disease for less than 5 years. Of the 289 patients who completed the study, 87.5% were on levodopa therapy versus other anti-parkinsonian medications. The duration of levodopa therapy for these patients was 1.96+1.53 years.
Investigators found that the clinical assessment identified "wearing off" in 85 patients (29.4%) compared with 165 patients (57.1%) who self-reported symptoms of "wearing off" on the patient questionnaire. When asked about difficulties associated with these symptoms, 40% of respondents indicated that the symptoms were at least very troublesome. The most commonly listed troublesome symptoms included tremor, balance difficulty, and reduced dexterity.
Parkinson's disease, a chronic and progressive neurological condition, affects approximately 1.5 million Americans. Symptoms include limbs that tremble; slowness of movement; stiffness and rigidity of limbs and gait or balance problems. As the disease progresses, these symptoms usually increase and impact a person's ability to work and function.