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

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.