Respondent burden and patient-perceived validity of the PDQ-39.

OBJECTIVES To evaluate the respondent burden and patient-perceived content validity of the Parkinson's disease (PD)-specific health status questionnaire PDQ-39, and the linguistic validity of its revised Swedish version. MATERIALS AND METHODS Eighteen PD patients completed the revised Swedish version of the PDQ-39. Respondent burden was assessed by recording the time taken to complete the questionnaire. Content and linguistic validity was evaluated qualitatively. RESULTS Patients with mild, moderate and advanced PD needed a mean time of 9.5, 11.3 and 20.1 min, respectively, to complete the PDQ-39. One-third of the patients identified irrelevant items and 50% identified important health-related areas that were missing. Revisions had eliminated previous linguistic problems with the Swedish PDQ-39. CONCLUSIONS Undue respondent burden challenged the appropriateness of the PDQ-39 among patients with more advanced disease. Overall content validity was acceptable but compromised by lack of important content areas. Observations supported the linguistic validity of the revised Swedish PDQ-39.