Browsing by Subject "clinimetrics"

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    It Is as It Was: MDS-UPDRS Part III Scores Cannot Be Combined with Other Parts to Give a Valid Sum.
    (Movement disorders : official journal of the Movement Disorder Society, 2022-12) Goetz, Christopher G; Choi, Dongrak; Guo, Yuanyuan; Stebbins, Glenn T; Mestre, Tiago A; Luo, Sheng

    Background

    Original clinimetric analyses by the Movement Disorder Society-sponsored revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS) developers did not confirm the validity of summing the scores of its parts. Recent studies used the summed score of Part III and other parts as efficacy outcomes.

    Objective

    The aim of this study was to establish whether summing scores of MDS-UPDRS parts can be recommended.

    Methods

    Using 7466 full MDS-UPDRS scores, we applied two-step factor analysis as in the original article to reassess the validity analysis with the threshold criterion set at comparative fit index ≥0.9.

    Results

    All comparative fit indexes of any combination including Part III were lower than 0.90.

    Conclusions

    Summing Part III MDS-UPDRS scores with other parts is not clinimetrically sound. The MDS-UPDRS is a validated four-part scale with corresponding individual part scores and needs to be used within the limits originally presented. © 2022 International Parkinson and Movement Disorder Society.
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    Item Response Theory Analysis of the MDS-UPDRS Motor Examination: Tremor vs. Nontremor Items.
    (Movement disorders : official journal of the Movement Disorder Society, 2020-05-29) Tosin, Michelle Hyczy de Siqueira; Goetz, Christopher G; Luo, Sheng; Choi, Dongrak; Stebbins, Glenn T
    BACKGROUND:In PD, tremor severity behaves differently from other core motor features. However, the most commonly used assessment of overall motor severity, total MDS-UPDRS Motor Examination (Part 3) score, does not account for this distinction. OBJECTIVES:To investigate the Motor Examination (Part 3) using Item Response Theory approaches focusing on sample-independent strategies that assess how well items measure latent models of PD motor severity. METHODS:Data from 6,298 PD patients were analyzed with graded response model Item Response Theory approaches involving two analyses all 33 Part 3 items versus the 10 tremor items and 23 bradykinesia, rigidity, gait, and posture items considered separately. The strength of relationship between items and the latent measure of parkinsonian motor severity (discrimination parameter) and calculated thresholds (location parameters) were assessed using the mirt program implemented in R (R Foundation for Statistical Computing, Vienna, Austria). RESULTS:Analyzing all Part 3 items together, nontremor items demonstrated good discrimination parameters (mean = 1.83 ± 0.37) and range of thresholds (-1.73 to +4.42), but tremor items had poor discrimination (mean = 0.52 ± 0.76) and thresholds (-0.69 to 14.29). Segregating nontremor from tremor items in two independent analyses provided markedly improved discrimination and location parameters for both. CONCLUSIONS:MDS-UPDRS Part 3 tremor and nontremor items have very different relations to the construct of PD severity. Strongly improved clinimetric properties for Part 3 are obtained when tremor and nontremor items are considered separately. We suggest that evaluating PD motor severity, as an operationalized summary measure, is best attained through separate analyses with tremor and nontremor motor scores. © 2020 International Parkinson and Movement Disorder Society.
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    Reply to: Comment on "Summing MDS-UPDRS Parts 1 + 2 (Non-motor and Motor Experience of Daily Living): The Patient's Voice".
    (Movement disorders : official journal of the Movement Disorder Society, 2023-08) Goetz, Christopher G; Zou, Haotian; Stebbins, Glenn T; Schrag, Anette; Mestre, Tiago A; Luo, Sheng
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    Summing MDS-UPDRS Parts 1 + 2 (Non-motor and Motor Experience of Daily Living): The Patient's Voice.
    (Movement disorders : official journal of the Movement Disorder Society, 2023-04) Zou, Haotian; Goetz, Christopher G; Stebbins, Glenn T; Schrag, Anette; Mestre, Tiago A; Luo, Sheng