Validation of a Clinical Scale for Defining RBD Severity in Participants of the North American Prodromal Synucleinopathy (NAPS) Consortium (P2-7.001)

Objective: The objective of this study is to assess the validity of the REM Sleep Behavior Disorder (RBD) symptom severity scale (RBDSSS) and its correlation to the clinical global impression of severity (CGI-S) in a cohort of participants enrolled in the North American Prodromal Synucleinopathy (NAPS) study.

Background: RBD is a prodromal marker of α-synucleinopathies with no standardized tool for assessing severity in clinical or research practice. Development of a reliable scale is essential to understand risk of phenoconversion, monitor response to treatment and clinical trial design.

Design/Methods: Participants and their bedpartners enrolled in the NAPS cohort filled out an 8-item questionnaire (RBDSSS), developed by the International RBD Study Group, assessing frequency and severity of dreams, vocalizations, movements, and injuries associated with RBD, with higher scores indicating more severe symptoms. The CGI-S is a 7-point scale ranging from normal (1) to most severely ill (7) and was completed by a clinician based on an independent interview with the participant ± their bedpartners. Data were included when both patient (RBDSSS-PT) and bedpartner (RBDSSS-BP) responses were available. Total scores were derived by multiplying assigned point values for frequency and severity (for each question) and summing them for individual RBDSSS-PT scores (total possible=54) and RBDSSS-BP scores (total possible=38).

Results: The cohort (n=212) included in this analysis was predominantly male (n=175) with a mean ± SE age of 65.16 ± 1.46 years. The median (interquartile range) for RBDSSS-PT, RBDSSS-BP and CGI-S was 11 (4–17), 8 (4–14.3) and 3 (3–4), respectively. Nonparametric Spearman’s rank correlation coefficients (r_s) for each variable pair are as follows: RBDSSS-PT vs. RBDSSS-BP, r_s=0.576; RBDSSS-PT vs. CGI-S, r_s=0.641; RBDSSS-BP vs. CGI-S, r_s=0.463 (P<0.0001).

Conclusions: A moderate correlation was observed between RBDSSS-PT and RBDSSS-BP, suggesting good construct validity for the scale. CGI-S correlated moderately with RBDSSS-PT and weakly with RBDSSS-BP.

Disclosure: Ms. Busicescu has nothing to disclose. Dr. Choudhury has nothing to disclose. Dr. Lee-Iannotti has received personal compensation for serving as an employee of Jazz Pharmaceuticals . Dr. Lee-Iannotti has received personal compensation in the range of $5,000-$9,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Jazz Pharmaceuticals . Dr. Lee-Iannotti has received personal compensation in the range of $5,000-$9,999 for serving on a Speakers Bureau for Jazz Pharmaceutical. Dr. Lee-Iannotti has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Harmony Biosciences. Dr. Rangan has nothing to disclose. Dr. Shprecher has received personal compensation for serving as an employee of Banner Health. Dr. Shprecher has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Amneal. Dr. Shprecher has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Forensis. Dr. Shprecher has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Neurocrine. Dr. Shprecher has received personal compensation in the range of $500-$4,999 for serving as a Consultant for US World Meds. Dr. Shprecher has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Emalex. Dr. Shprecher has received personal compensation in the range of $10,000-$49,999 for serving on a Speakers Bureau for Teva. Dr. Shprecher has received personal compensation in the range of $10,000-$49,999 for serving on a Speakers Bureau for Neurocrine. Dr. Shprecher has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Acorda. Dr. Shprecher has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Sunovion. Dr. Shprecher has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for US World Meds. Dr. Shprecher has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Amneal. The institution of Dr. Shprecher has received research support from Arizona Alzheimer's Consortium. The institution of Dr. Shprecher has received research support from MJFF. The institution of Dr. Shprecher has received research support from Abbvie. The institution of Dr. Shprecher has received research support from Acadia. The institution of Dr. Shprecher has received research support from Axovant. The institution of Dr. Shprecher has received research support from Biogen. The institution of Dr. Shprecher has received research support from Eisai. The institution of Dr. Shprecher has received research support from Eli Lilly. The institution of Dr. Shprecher has received research support from Enterin. The institution of Dr. Shprecher has received research support from Neurocrine. The institution of Dr. Shprecher has received research support from Teva. The institution of Dr. Shprecher has received research support from Nuvelution. The institution of Dr. Shprecher has received research support from Theravance. The institution of Dr. Shprecher has received research support from Eisai. The institution of Dr. Shprecher has received research support from Sanofi. The institution of Dr. Shprecher has received research support from Neuraly. Maria Livia Fantini has nothing to disclose. The institution of Dr. Lim has received research support from NIH. The institution of Dr. Lim has received research support from VA. The institution of Dr. Lim has received research support from Department of Defense. 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