The Movement Disorder Society Task Force for Rating Scales for Parkinson's disease (PD) prepared a critique of the Hoehn and Yahr scale (HY). Strengths of the HY scale include its wide utilization and acceptance. Progressively higher stages correlate with neuroimaging studies of dopaminergic loss, and high correlations exist between the HY scale and some standardized scales of motor impairment, disability, and quality of life. Weaknesses include the scale's mixing of impairment and disability and its non-linearity. Because the HY scale is weighted heavily toward postural instability as the primary index of disease severity, it does not capture completely impairments or disability from other motor features of PD and gives no information on nonmotor problems. Direct clinimetric testing of the HY scale has been very limited, but the scale fulfills at least some criteria for reliability and validity, especially for the midranges of the scale (Stages 2-4). Although a "modified HY scale" that includes 0.5 increments has been adopted widely, no clinimetric data are available on this adaptation. The Task Force recommends that: (1) the HY scale be used in its original form for demographic presentation of patient groups; (2) when the HY scale is used for group description, medians and ranges should be reported and analysis of changes should use nonparametric methods; (3) in research settings, the HY scale is useful primarily for defining inclusion/exclusion criteria; (4) to retain simplicity, clinicians should "rate what you see" and therefore incorporate comorbidities when assigning a HY stage; and (5) because of the wide usage of the modified HY scale with 0.5 increments, this adaptation warrants clinimetric testing. Without such testing, however, the original five-point scales should be maintained.

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Movement Disorder Society Task Force report on the Hoehn and Yahr staging scale: status and recommendations.

Objectives: to briefly outline the development and validation of the Parkinson's Disease Questionnaire (PDQ-39) and then to provide evidence for the use of the measure as either a profile of health status scores or a single index figure. Design: the PDQ-39 was administered in two surveys: a postal survey of patients registered with local branches of the Parkinson's Disease Society of Great Britain (n = 405) and a survey of patients attending neurology clinics for treatment for Parkinson's disease (n = 146). Data from the eight dimensions of the PDQ-39 were factor-analysed. This produced a single factor on the data from both surveys. Outcome measures: the eight dimensions of the PDQ-39 and the new single index score—the Parkinson's disease summary index (PDSI), together with clinical assessments (the Columbia rating scale and the Hoehn and Yahr staging score). Results: in the postal survey 227 patients returned questionnaires (58.2%). All 146 patients approached in the clinic sample agreed to take part. Higher-order principal-components factor analysis was undertaken on the eight dimensions of the PDQ-39 and produced one factor on both datasets. Consequently it was decided that the scores of the eight domains could be summed to produce a single index figure. The psychometric properties of this index were explored using reliability tests and tests of construct validity. The newly derived single index was found to be both internally reliable and valid. Discussion: data from the PDQ-39 can be presented either in profile form or as a single index figure. The profile should be of value in studies aimed at determining the impact of treatment regimes upon particular aspects of functioning and well-being in patients with Parkinson's disease, while the PDSI will provide a summary score of the impact of the illness on functioning and well-being and will be of use in the evaluation of the overall effect of different treatments. Furthermore, the PDSI reduces the number of statistical comparisons and hence the role of chance when exploring data from the PDQ-39.

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The Parkinson's Disease Questionnaire (PDQ-39): development and validation of a Parkinson's disease summary index score

Parkinson's disease is a common degenerative neurological condition. A number of general health status measures exist but these may not address areas salient to specific diseases. We report here the development and validation of a short 39 item health status questionnaire for use in Parkinson's disease. Questionnaire items, generated from in-depth interviews with people with Parkinson's disease, were developed into a 65 item questionnaire. Data from a postal survey using the 65 item questionnaire were statistically analysed to produce a shorter questionnaire with 39 items and eight scales addressing different dimensions of Parkinson's disease. A second postal survey was conducted in order to assess the reliability and validity of the new 39 item questionnaire. The final questionnaire, referred to here as the 39 item Parkinson's Disease Questionnaire (PDQ-39), proved to have satisfactory internal and test-retest reliability, and construct validity in relation to other measures, reported by respondents with Parkinson's disease.

The development and validation of a short measure of functioning and well being for individuals with Parkinson's disease.

We assessed the clinometric characteristics of rating scales used for the evaluation of motor impairment and disability of patients with Parkinson's disease (PD), conducting a systematic review of PD rating scales published from 1960 to the present. Thirty studies describing clinometrics of 11 rating scales used for PD were identified. Outcome measures included validity (including factor structure), reliability (internal consistency, inter-rater, and intrarater) and responsiveness. We traced three impairment scales (Webster, Columbia University Rating Scale [CURS] and Parkinson's Disease Impairment Scale), four disability scales (Schwab and England, Northwestern University Disability Scale [NUDS], Intermediate Scale for Assessment of PD, and Extensive Disability Scale), and four scales evaluating both impairment and disability (New York University, University of California Los Angeles, Unified Parkinson's Disease Rating Scale [UPDRS], and Short Parkinson Evaluation Scale). The scales showed large differences in the extent of representation of items related to signs considered responsive to dopaminergic treatment or to those signs that appear late in the disease course and lack responsiveness to treatment. Regardless of the scale, there was a conspicuous lack of consistency concerning inter-rater reliability of bradykinesia, tremor, and rigidity. Overall disability items displayed moderate to good inter-rater reliability. The available evidence shows that CURS, NUDS, and UPDRS have moderate to good reliability and validity. In contrast to their widespread clinical use for assessment of impairment and disability in PD, the majority of the rating scales have either not been subjected to an extensive clinometric evaluation or have demonstrated clinometric shortcomings. The CURS, NUDS, and UPDRS are the most evaluated, valid, and reliable scales currently available.

Systematic evaluation of rating scales for impairment and disability in Parkinson's disease.

The Parkinson's Disease Questionnaire (PDQ-39) is a disease specific measure of health status which covers eight dimensions of ill-health, and contains 39 questions. The development of the question...

The PDQ-8: Development and validation of a short-form parkinson's disease questionnaire

Inter- and intrarater reliability in scoring the signs of Parkinson's disease using the original Columbia scale and a modified version of this, the Sydney scale, were assessed in five neurologists participating in a long-term study of Parkinson's disease. Scoring was done on video recordings of 41 patients whose disability ranged from mild to severe. Although all the neurologists were familiar with the scales and had received training designed to produce uniformity of scoring, interrater reliability was poor. The mean score for the Columbia scale varied from 18.6 to 30 and for the Sydney scale from 15.2 to 23.2. By contrast, intrarater reliability was good. This study highlights the limitations of clinical rating scales in Parkinson's disease when more than one rater is used. In designing clinical trials, every effort should be made to ensure that the same patient is always assessed by the same rater.

A. Wilson

Papers

Reliability of the Columbia scale for assessing signs of Parkinson's disease.