Introduction: Clinical parkinsonism is a core diagnostic feature for mild cognitive impairment with Lewy bodies (MCI-LB) but can be challenging to identify. A five-item scale derived from the Unified Parkinson's Disease Rating Scale (UPDRS) has been recommended for the assessment of parkinsonism in dementia. This study aimed to determine whether the five-item scale is effective to identify parkinsonism in MCI.
Methods: Participants with MCI from two cohorts (n = 146) had a physical examination including the UPDRS and [123I]-FP-CIT SPECT striatal dopaminergic imaging. Participants were classified as having clinical parkinsonism (P+) or no parkinsonism (P-), and with abnormal striatal dopaminergic imaging (D+) or normal imaging (D-). The five-item scale was the sum of UPDRS tremor at rest, bradykinesia, action tremor, facial expression, and rigidity scores. The ability of the scale to differentiate P+D+ and P-D- participants was examined.
Results: The five-item scale had an AUROC of 0.92 in Cohort 1, but the 7/8 cut-off defined for dementia had low sensitivity to identify P+D+ participants (sensitivity 25%, specificity 100%). Optimal sensitivity and specificity was obtained at a 3/4 cut-off (sensitivity 83%, specificity 88%). In Cohort 2, the five-item scale had an AUROC of 0.97, and the 3/4 cut-off derived from Cohort 1 showed sensitivity of 100% and a specificity of 82% to differentiate P+D+ from P-D- participants. The five-item scale was not effective in differentiating D+ from D- participants.
Conclusions: The five-item scale is effective to identify parkinsonism in MCI, but a lower threshold must be used in MCI compared with dementia.
Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests. Alan Thomas reports financial support was provided by Alzheimer's Research UK [ARUK-PG3026–13]; GE Healthcare and the NIHR Newcastle Biomedical Research Centre. GE Healthcare provided funding for FP-CIT imaging for this investigator-led study. Paul C Donaghy reports financial support was provided by the Medical Research Council [grant number MR/W000229/1]. Rishira Fernando reports financial support was provided by a Newcastle University Vacation Scholarship. John O'Brien reports financial support was provided by the NIHR Cambridge Biomedical Research Centre and the Cambridge Centre for Parkinson's Plus. Louise Allan reports financial support was provided by the Peninsula NIHR Applied Research collaboration and the Exeter NIHR Biomedical Research Centre. The views expressed are those of the author(s) and not necessarily those of the NIHR or the Department of Health and Social Care. The funders had no role in study design; in the collection, analysis and interpretation of data; in the writing of the report; or in the decision to submit the article for publication. George Petrides and John-Paul Taylor report a relationship with GE Healthcare that includes: speaking and lecture fees. John O'Brien reports a relationship with TauRx, Novo Nordisk, Biogen, Roche, Lilly and GE Healthcare that includes: consulting or advisory. John O'Brien reports a relationship with Avid/Lilly, Merck and Alliance Medical that includes: funding grants. The other authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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