Development of an Exercise-Specific Parkinson's Disease Questionnaire: The PDQ-Exercise.

Background Exercise is now a significant and key component in the management of Parkinson's disease. However, no self-report, Parkinson's-specific measure of exercise currently exists. Objective To develop a patient-reported outcome measure (PROM) for use in studies and clinical trials that aim to assess the efficacy of exercise therapy for people with Parkinson's (PwP). Methods Participants were recruited via Parkinson's UK. To generate meaningful items, PwP participated in exploratory cognitive interviews. To pretest the items generated, PwP took part in two rounds of cognitive debrief interviews. Items were subsequently tested through an online survey that also included the eight-item Parkinson's Disease Questionnaire (PDQ-8) and Oxford Participation and Activities Questionnaire (Ox-PAQ). Results Twenty PwP were interviewed for item generation. Analyses identified issues related to adopting and maintaining exercise, resulting in the generation of 10 items. Fourteen PwP took part in subsequent cognitive debrief interviews. Following the first 10 interviews, one item was removed, and minor adjustments were made to the wording of two items. Four final interviews verified that no further adjustments were required. Consequently, nine items were included in the validation survey, which was fully completed by 398 PwP. Inspection of floor and ceiling effects resulted in the removal of two further items. A principal component analysis identified a single seven-item factor explaining 61.6% of variance. Further analyses indicated that the measure demonstrates sound reliability and validity. Conclusions Results indicate that the PDQ-Exercise is an acceptable, reliable, and valid PROM. Further assessment of its psychometric properties is in progress. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.