Assessing the validity of proxy caregiver reporting for potential palliative care outcome measures in Parkinson’s disease

Abstract

Background: There is increasing interest in applying palliative care approaches for patients with Parkinson’s disease. Methodological studies are needed to validate palliative care outcome measures for Parkinson’s disease to build this evidence base. As many patients with Parkinson’s disease have cognitive and/or communication issues, proxy outcome measures may improve the inclusivity and relevance of research. Aim: To assess the validity of proxy caregiver reports for several potential palliative care outcome measures. Design: A cross-sectional study of Parkinson’s disease patients and caregivers completed a battery of outcome measures relevant to palliative care including the Memorial Symptom Assessment Scale, Hospital Anxiety and Depression Scale, Prolonged Grief Questionnaire 12, Parkinson Disease Questionnaire 39, Functional Assessment of Chronic Illness Therapy–Spiritual Wellbeing, and Schwab and England. Intraclass correlation coefficients were used to assess agreement. Setting/participants: A total of 50 Parkinson’s disease patient and caregiver dyads recruited at an academic medical center, Veterans Affairs Medical Center, and community support groups. Results: There was moderate to good agreement for Schwab and England, Parkinson Disease Questionnaire 39 total, and majority of Parkinson Disease Questionnaire 39 subscales; moderate to good agreement for the Hospital Anxiety and Depression Scale, Functional Assessment of Chronic Illness Therapy–Spiritual Wellbeing, Prolonged Grief Questionnaire 12, and Memorial Symptom Assessment Scale; and poor to moderate agreement for the Parkinson Disease Questionnaire 39 stigma, social support, and bodily pain subscales. Caregivers tended to attribute higher symptom severity than patients. We did not detect differences in intraclass correlation coefficient based on cognitive status but patients with advanced illness had significantly lower intraclass correlation coefficients for several outcomes. Conclusions: Caution is indicated when considering caregiver proxy reporting for most outcomes assessed, particularly in Parkinson’s disease patients with advanced disease.