Objective: To investigate the reliability of scores of the motor part of the Unified Parkinson Disease Rating Scale (UPDRS III) rated by an un-blinded specialist nurse compared to scores rated by two blinded movement disorders clinicians.

Background: Blinded scoring of the motor UPDRS is considered a gold standard for objective evaluation of the severity of Parkinson´s disease (PD). However, the reliability of un-blinded scoring by a specialist nurse compared to blinded scoring by clinicians is not known.

Method: A total of 60 scorings of the UPDRS III were performed on patients with advanced PD: 28 scorings were done on 14 patients who underwent a L-dopa challenge (14 in off-medication condition and 14 in on-medication condition) and 32 scorings were done on 8 of the patients at 6 months after bilateral DBS of the caudal zona incerta (8 off-med off-stim; 8 off-med on-stim; 8 on-med off-stim; 8 on-med on-stim). Scorings were performed by an un-blinded specialist nurse, and by two blinded movement disorders clinicians on standardized videos presented in random order.

Results: There were no differences between un-blinded nurse UPDRS III scores and blinded clinicians scores in the 14 patients who underwent L-dopa challenge (39.1±14 vs. 41.3±11, p=ns in off-med, and 21.5±13 vs. 21.2±11, p=ns in on-med condition). In the 8 DBS patients, there were only differences in scores off-med off-stim (blinded 35.4±10, un-blinded 37.7±10, p=0.049) and in on-med on-stim (blinded 19.2±12, un-blinded 14.6±10, p=0.012).

Conclusion: According to a recently published expert consensus, “a five-point UPDRS III difference represents a clinically meaningful difference” (Sanchez-Ferro A et al: Minimal Clinically Important Difference for UPDRS-III in Daily Practice. Mov Disord Clin Pract, 2018). In our patients, differences in UPDRS III scores between un-blinded specialist nurse and blinded clinicians were rare, and when they occurred the differences were below the established minimal clinically pertinent limits. Un-blinded evaluations of UPDRS III by an expert nurse can be considered as valid and reliable.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/how-reliable-are-non-blinded-evaluations-of-motor-updrs-a-comparison-of-blinded-vs-un-blinded-updrs-scores-in-14-patients-with-advanced-parkinsons-disease/