Measuring quality of life in palliative care for Parkinson's disease: A clinimetric comparison

Introduction: Quality of life (QOL) assessments allow for more complete evaluation of patients' lived experiences in relation to chronic conditions, such as Parkinson's disease (PD). In palliative care, such instruments are vital to ensure QOL issues are catalogued and addressed for patients. However, little is known regarding the psychometric properties of quality of life scales for use in palliative care for PD, specifically. Methods: 210 participants with parkinsonian disorders, who participated in a larger palliative intervention clinical trial, completed four quality of life scales (PDQ-39, PROMIS-29, QOL-AD, and McGill QOL) at baseline and post-intervention. Psychometric properties, including internal consistency and concurrent validity, were examined. Factor analyses were performed to evaluate relationships between scale items. Minimal clinically important differences (MCID) and responsiveness were calculated for each scale. Results: All scales demonstrated good internal consistency and concurrent validity. Factor analyses revealed few deviations from the defined subdomains of the scales. Mean absolute MCID values were estimated at 12.7, 10.9, 3.9, and 18.9 for PDQ-39, PROMIS-29, QOL-AD, and McGill QOL, respectively. The PDQ-39 and PROMIS-29 demonstrated higher responsiveness to palliative intervention, while the QOL-AD was more responsive in the control group. Conclusions: The PDQ-39, PROMIS-29, QOL-AD, and McGill QOL are all valid for use in PD palliative care, though subdomains of the scales in this population may differ slightly from those initially defined. We recommend the use of PDQ-39 and PROMIS-29 as outcome measures in clinical trials for palliative care in PD, though the QOL-AD may be superior for tracking disease progression.