Measuring the impact of Parkinson's disease with the Parkinson's disease quality of life questionnaire

Objectives: to assess the validity of the Parkinson's Disease Quality of Life (PDQL) questionnaire, a patient-specific multi-dimensional quality of life measure, in a community-based sample of patients with Parkinson's disease (PD) using standardized measures of disease severity, depressive symptomatology and cognitive function. Design: a group of 194 patients with probable PD were randomly selected from a community-based register and were invited to self-complete the 37-item PDQL. Disease severity was measured by the disease-specific Webster scale, cognition by the CAMCOG neuropsychological test and depressive symptomatology by the self-report 15-item GDS-15 geriatric depression scale. Results: a total of 136 patients returned completed PDQL questionnaires. Significant differences (P < 0.05) emerged between the pooled PDQL score of patients grouped on the basis of disease severity. Depressive symptoms and cognition were also associated with poorer perceived quality of life as measured by the PDQL. Conclusions: the results of this study are indicative of the validity of the PDQL as an important additional measurement which reflects the impact of PD from the patient perspective. It shows poorer quality of life to be associated with increasing age, disease severity, more severe depressive symptomatology and impaired cognitive functioning. However, the responsiveness of this instrument in the evaluation of care in PD remains to be determined.