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Abstract Details

Conversion Rate of Essential Tremor to Essential Tremor-Parkinson’s Disease: Data from a Prospective, Longitudinal Study
Movement Disorders
S42 - Movement Disorders: Genetics and Risk Modifiers (5:18 PM-5:30 PM)
010
There has been a longstanding dialogue as to whether ET increases the risk of developing PD. While there are relevant cross-sectional data, there are almost no longitudinal, prospective data. 
We quantified the conversion rate from essential tremor (ET) to ET with Parkinson's disease (ETPD) in a prospective, longitudinal cohort study of ET cases. We compared the observed rate to that reported in the epidemiological literature. 

We enrolled ET cases in a prospective, longitudinal study. A senior movement disorders neurologist evaluated standardized neurological examinations every 18 months.

193 ET cases (mean age = 78.1 ± 9.6 years, range = 55 – 96) had a mean follow-up duration of 4.1 years. Seven (3.6%) converted from ET to ETPD. The incidence of PD among ET cases was 7/792.9 person years [py] (i.e., 882.8/100,000 py). A meta-analysis of the incidence (per 100,000 py) of PD in 14 studies from 13 countries across 4 continents reported an incidence of PD = 61.21 (males, >40 years) and 37.55 (females, >40 years). The incidence/100,000 py in males peaked in the 80 – 89 year old age group (258.47) and in females in the 80 – 89 year old age group (103.48 py). The above published values are 3.4 - 23.5 times lower than the value we observed for ET.

The incidence of PD in an ET cohort is substantially higher than that reported in historical, population-based control groups across numerous countries. Additional prospective, longitudinal data are needed to further explore this association.

Authors/Disclosures
Elan D. Louis, MD, MS, FAAN (University of Texas Southwestern Medical Center)
PRESENTER
Dr. Louis has received personal compensation in the range of $500-$4,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for Wolters Kluwer - Merritt's Textbook of Neurology. Dr. Louis has received personal compensation in the range of $500-$4,999 for serving as an Expert Witness for Legal Firm. The institution of Dr. Louis has received research support from National Institutes of Health. Dr. Louis has received publishing royalties from a publication relating to health care.
Diane Berry, PhD (University of Texas Southwestern Medical Center) Dr. Berry has nothing to disclose.
Ali Ghanem, MD (UT Southwestern Medical Center) Dr. Ghanem has nothing to disclose.
Stephanie Cosentino, PhD (Columbia University Medical Center) Dr. Cosentino has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Association for Frontotemporal Dementia. Dr. Cosentino has received personal compensation in the range of $500-$4,999 for serving as a Consultant for SAGE Pharmaceuticals.