Parkinson’s Disease Questionnaire – Exercise (PDQ-Exercise)

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The Parkinson’s Disease Questionnaire – Exercise (PDQ-Exercise) is the first Exercise-Specific Parkinson’s Disease Questionnaire.

A 7-item short questionnaire that can be administered as a stand-alone measure of quality of life in studies and clinical trials centred around exercise therapy or as a complement to the Parkinson’s Disease Questionnaire (PDQ). It was developed entirely on internal funding by the Health Services Research Unit, University of Oxford.

Background

Treatment for Parkinson’s disease (PD) has traditionally depended largely on pharmacological intervention. However, exercise is now also recognized as a significant and key component in the management of the condition. Despite the increasing prominence of exercise therapy in PD management, no self-report, Parkinson’s-specific measure of exercise existed, that was solely aimed at measuring these elements with adequate sensitivity. The PDQ-Exercise may help identify specific interventions and/or PD population groups for which exercise interventions will have the highest impact, levels of adherence, and compliance.

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Development

The PDQ-Exercise was developed in line with current best practice as provided by the United States Food and Drug Administration (FDA) and the European Medicines Agency (EMA) which place People with Parkinson’s (PwP) at the heart of the development process.

The study leading to the creation of the PDQ-Exercise comprises three phases: item generation interviews (20 PwP), pretesting (14 PwP), and a validation survey (398 PwP). Patients were recruited via Parkinson’s UK. Item generation interviews were face to face and qualitative to identify items of relevance that did not previously exist in the PDQ 39, pretesting helped further refine the items to generate a list of 9 that were put to the larger validation survey sample of patients.

Before the identification of the factor structure of PDQ-Exercise, floor and ceiling effects for each of the nine newly generated items were calculated, resulting in the removal of two items. The reliability of the PDQ-Exercise is demonstrated by ITCs that confirm individual item scores relate to the overall score. The validity of the new measure is established through the assessment of correlations with the PDQ-8 and the three domains of the Ox-PAQ.

Additional psychometric properties, such as test– retest reliability and sensitivity to change (thus allowing its use over time), are currently being assessed and will be reported in due course.

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Scoring System

The PDQ-Exercise is calculated as a single domain scale ranging from 0-100. Higher scores indicate greater problems with exercise related issues.

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Complementary PRO Measures

During the Item Generation Interviews patients were asked to complete the Thirty-Nine-Item Parkinson’s Disease Questionnaire (PDQ-39) electronically: The PDQ-39 comprises 39 items across 8 domains: mobility, activities of daily living, emotional well-being, stigma, social support, cognitions, communication, and bodily discomfort. The measure demonstrates excellent validity, reliability, and sensitivity to change. During the Validation Survey patients completed the PDQ-8 and the Ox-PAQ: The PDQ-8 is a short-form version of the PDQ-39, with one item from each of the eight domains of the parent measure. The measure generates a single index score on a scale of 0 to 100. Oxford Participation and Activities Questionnaire (Ox-PAQ) is a 23-item measure of activity and participation across three domains: routine activities, emotional well-being, and social engagement. The measure demonstrates sound validity, reliability, and sensitivity to change.

Users can cover quality of life in wider scope studies by utilising an appropriate combination of these measures although specific correlation data is not yet available.

 

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Administration Methods

Although validated in electronic format, previous postal surveys using the PDQ-39 indicate that the PDQ-Exercise could legitimately be administered in paper-based format.

 

Pen and Paper ePRO/eCOA – Computer-based administration

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