Caregiver strain in Parkinson's disease: National Parkinson Foundation Quality Initiative Study

Background: National Parkinson Foundation Quality Improvement Initiatives (NPF-QII) is the first large scale data-driven initiative in Parkinson's disease (PD) aimed at identifying variables predicting best care models and outcomes. Objective: To determine what measures of PD disability, demographics, and patient quality of life are associated with caregiver strain among caregivers of patients with PD. Methods: All PD patients at 18 participating sites are eligible for enrollment into the NPF-QII registry. Dataset includes multidimensional measures of disease severity, health care utilization, PD quality of life questionnaire-39 (PDQ-39) and multidimensional caregiver strain inventory (MCSI). A univariate as well as an adjusted analysis was performed to examine the relationship between caregiver strain and variables of PD disability. Results: The single best factor associated with high caregiver strain was the PDQ-39 total score (c-statistic of continuous variable=0.792, p<0.001) followed by the PDQ-mobility subscore (c=0.776, p<0.001). PDQ-39≥47 was the optimal cut off associated with a high caregiver strain with a sensitivity=83% and specificity=64%. A multiple logistic regression model with stepwise selection showed that in addition to PDQ-39≥47 (OR and 95% confidence interval=5.1 (3.2, 8.2), the following subject characteristics were associated with high caregiver strain: (model p<0.001, c=0.838): Hoehn and Yahr stage >3 (2.0 (1.3, 3.1)), presence of concomitant medications such as antidepressants (2.1 (1.5, 3.1)) and antipsychotics (2.5 (1.5, 4.2)), social worker visits (1.6 (1.2, 2.1)), male gender (2.3 (1.5, 3.5)), and decreased verbal fluency (0.95 (0.92, 0.98)). Conclusions: There is a high prevalence of caregiver strain in PD. PDQ-39 total score has the strongest association with high levels of caregiver strain. These results could guide clinicians in the assessment of caregivers at risk.