Cross-cultural evaluation of the Parkinson's Disease Questionnaire: tests of data quality, score reliability, response rate, and scaling assumptions in the United States, Canada, Japan, Italy, and Spain.
Jenkinson C., Fitzpatrick R., Norquist J., Findley L., Hughes K.
BACKGROUND AND OBJECTIVES: Health status measures, used to measure the subjective functioning and well-being of respondents, are increasingly being used in trials of treatments that are undertaken in a variety of countries. To assess comparability of results gained from such cross-cultural studies, it is important for researchers to know the comparability of instruments across cultures. One measure widely used in cross-cultural studies is the Parkinson's Disease Questionnaire (PDQ-39). We evaluated response rate, data quality, score reliability, and scaling assumptions of the instrument in the United States, Canada, Spain, Italy, and Japan. METHODS: Our data were gained from the Global Parkinson's Disease Survey, a cross-national survey, in which the PDQ-39 was interviewer administered to respondents. RESULTS: Our data suggest that the PDQ-39 is, for the most part, a valid and reliable measure that can be appropriately and meaningfully used in cross-cultural studies. However, one of the dimensions of the measure, Social Support, may not be sufficiently reliable to be used as a primary endpoint in trials. CONCLUSION: The PDQ-39 seems to be sufficiently robust to be used in trials and surveys in cross-cultural studies.