Feasibility and linguistic validity of the Swedish version of the PDQ-39.

The Parkinson's Disease Questionnaire - 39 is the most widely used disease-specific health status questionnaire for Parkinson's disease. Evaluations of various language versions have focused on psychometric properties, whereas documented evaluations regarding linguistic validity, respondent burden and questionnaire content are largely lacking. Work with the Swedish Parkinson's Disease Questionnaire - 39 has taken these aspects into account, which has resulted in a linguistically revised version which is currently being evaluated. Initial observations indicate that the revision rectified linguistic but not nonlinguistic problems, and that its feasibility in terms of respondent burden in more advanced disease can be challenged. There are also indications for the need for content improvements. These experiences are discussed along with their implications.