A review of health-related quality-of-life concepts and measures for Parkinson's disease

Parkinson's disease affects individuals' health-related quality of life (HQ L). Including standardized HQL assessments in therapeutic clinical trials w ill broaden our understanding of treatment efficacy. Selecting appropriate HQL measures for clinical studies requires consideration of their comprehen siveness, psychometric properties and feasibility. To facilitate selection, this manuscript reviews the HQL areas affected by Parkinson's disease and available Parkinson's disease-specific HQL measures: the Parkinson's Diseas e Questionnaire-39 (PDQ-39) and the Parkinson's Disease Quality-of-Life Que stionnaire (PDQL). Based on a literature review and consultation with HQL e xperts, five clinicians and three patients, 12 areas of HQL were identified as particularly relevant to Parkinson's disease: physical function, mental health/emotional well being, self-image, social function, health-related d istress, cognitive function, communication, sleep and rest, eating, role fu nction, energy/fatigue, and sexual function. The PDQ-39 measures all areas except for self-image and sexual function. The PDQL measures all areas exce pt for eating and role function. Both measures are brief and are designed a nd validated to be self-completed by patients. Both measures demonstrate ad equate internal consistency (PDQ-39: 0.72-0.95; PDQL: 0.80-0.87) and eviden ce of cross-sectional validity with patient-reported measures of similar co ncepts. The PDQ-39 also demonstrates reproducibility (0.68-0.94), significa nt associations with clinical measures and preliminary evidence of responsi veness. Applications of the PDQ-39 and PDQL to clinical trials will contrib ute greatly towards their continued validation and interpretation.