Related Experiment Videos
Determining minimally important differences for the PDQ-39 Parkinson's disease questionnaire
V Peto1, C Jenkinson, R Fitzpatrick
1Health Services Research Unit, Department of Public Health, Institute of Health Sciences, University of Oxford, Oxford OX3 7LF, UK.
Age and Ageing
|August 18, 2001
Summary
The minimally important difference (MID) for the Parkinson's Disease Questionnaire-39 (PDQ-39) varies across its dimensions. Researchers should select specific PDQ-39 dimensions for sample size calculations based on primary study outcomes.
Area of Science:
- Neurology
- Psychometrics
- Clinical Trials
Background:
- The Parkinson's Disease Questionnaire-39 (PDQ-39) is a widely used measure for assessing quality of life in Parkinson's disease.
- Understanding the minimally important difference (MID) is crucial for interpreting changes in PDQ-39 scores and for designing robust clinical studies.
Purpose of the Study:
- To determine the minimally important differences (MIDs) for each dimension of the PDQ-39.
- To provide essential data for sample size calculations in Parkinson's disease research.
Main Methods:
- A postal survey was conducted with members of the Parkinson's Disease Society, who completed the PDQ-39 twice, 6 months apart.
- Participants reported their perceived change in overall health and specific PDQ-39 domains since baseline.
Main Results:
- Minimally important differences were calculated for each PDQ-39 dimension and the overall index score.
- The MID values demonstrated variability across the different dimensions of the questionnaire.
Conclusions:
- The findings highlight that MIDs differ across PDQ-39 dimensions, influencing the interpretation of score changes.
- Researchers should carefully select the primary PDQ-39 dimension of interest when calculating sample sizes for studies evaluating treatment effects or disease progression.