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Abstract Details

Composite Measures of Prodromal Parkinson’s Disease and the Probability of Phenoconversion at 3 Years
Movement Disorders
S37 - Movement Disorders: Phenotyping and Biomarkers (1:24 PM-1:36 PM)
003
Features suggestive of prodromal PD are individually insufficient for early disease detection. Using composite measures may improve predictive validity and capture a more representative patient population.   
To assess the ability of composite measures of prodromal Parkinson’s disease (PD) to predict phenoconversion at 3 years. 
The study population comprised 19,757 individuals without PD at baseline (2014-2015). Two composite measures were created: i) the co-occurrence of probable REM sleep behavior disorder (pRBD), constipation and hyposmia, 3 major features of prodromal PD, and ii) a probability score which incorporated information on 8 risk (e.g., sex, physical inactivity) and 7 prodromal markers following the MDS research criteria. For each composite measure we calculated the positive predictive value (PPV) of being diagnosed with PD within 3 years. We additionally calculated the PPV for pRBD, constipation and hyposmia independently, and that of all 3 features along with parkinsonism. We repeated analyses restricting to participants <70 years old.
Between 2014-15 and 2017-18, we identified a total of 86 incident PD cases.  The PPV of being diagnosed with PD within 3 years was 2.48% for those with the 3 prodromal features, 2.62% for those with possible prodromal PD (score≥0.5) and 4.55% for those with probable prodromal PD (score≥0.8). The PPV of individual features was lower than those of the composite measures. Parkinsonism plus the co-occurrence of 3 features resulted in the highest PPV (11.8%). Measures based on the presence of 3 features performed somewhat better among men than women. The PPVs of measures based on the MDS score or parkinsonism were higher among those aged <70 years.

The ability to predict phenoconversion at 3 years was comparable between the two composite measures evaluated. The performance of composite measures was superior to that of individual features. Longer follow-up may be needed to better understand the validity of these measures.

Authors/Disclosures
Mario H. Torres (Harvard T.H. Chan School of Public Health)
PRESENTER
Mr. Torres has nothing to disclose.
Katherine C. Hughes, PhD (Optum) Dr. Hughes has received personal compensation for serving as an employee of Optum.
Kjetil Bjornevik, MD, PhD (Harvard T.H. Chan School of Public Health) The institution of Dr. Bjornevik has received research support from Michael J. Fox Foundation. The institution of Dr. Bjornevik has received research support from National Multiple Sclerosis Society. The institution of Dr. Bjornevik has received research support from Department of Defense.
Marianna Cortese, MD, PhD (Harvard T.H. Chan School of Public Health) Dr. Cortese has received personal compensation in the range of $500-$4,999 for serving as a speaker at educational event with Roche.
Albert Hung, MD, PhD (Massachusetts General Hospital) The institution of Dr. Hung has received research support from Parkinson's Foundation. The institution of Dr. Hung has received research support from Rho, Inc..
Michael Schwarzschild, MD, PhD (Massachusetts General Hospital) The institution of Dr. Schwarzschild has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Bial Biotech (indirectly, as a service of the Parkinson Study Group service). The institution of Dr. Schwarzschild has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Biogen (indirectly, as a service of the Parkinson Study Group service). The institution of Dr. Schwarzschild has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for UCB (indirectly, as a service of the Parkinson Study Group service). Dr. Schwarzschild has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Eli Lilly. The institution of Dr. Schwarzschild has received research support from NIH. The institution of Dr. Schwarzschild has received research support from Parkinson's Foundation. The institution of Dr. Schwarzschild has received research support from Michael J Fox Foundation. The institution of Dr. Schwarzschild has received research support from Farmer Family Foundation. Dr. Schwarzschild has a non-compensated relationship as a Chair, Executive Committee with the Parkinson Study Group that is relevant to AAN interests or activities.
Alberto Ascherio, MD, PhD The institution of Dr. Ascherio has received research support from NIH and US Department of Defense .