The objective is to investigate the association between caregiver burden and the biomarker, soluble urokinase-type plasminogen activator receptor (SuPAR), in healthy volunteers.

Previous studies have reported elevated serum levels of inflammatory markers in caregivers for individuals with neurologic illness. Additionally, SuPAR, a biomarker of systemic inflammation, has been associated with increased morbidity and mortality. The relationship between caregiver burden and SuPAR levels has not yet been explored.

Healthy volunteers were recruited from Rush University Movement Disorder Clinic in an observational cohort study assessing serum immune biomarkers. Caregiver status and burden was assessed using a Short Form Zarit Burden Interview (ZBI-12). For continuous variables, we used a T-test for normally distributed data and a Wilcoxon rank-sum test if not. For categorical variables, we used Chi-squared test or Fisher’s exact test.

Primary and non-primary caregivers were similar in mean age (60.9 vs 64.3 years respectively, p=0.3).  Primary caregivers were 57.14% female vs. 36.6% female in the non-primary caregiver cohort (p=0.26). Groups were similar in education (p=0.43), race (p=1.0), ethnicity (p=0.34), smoking history (p=0.91), smoking status (p=1.0), and rates of family history of autoimmune disease or neurological disease (p= 0.45, and 0.14 respectively). Primary caregivers had elevated SuPAR compared to non-primary caregivers (3.73 vs. 2.72 ng/mL, p=0.01). Primary caregivers also exhibited significantly higher ZBI-12 scores in comparison to non-primary caregivers (18.57 vs. 5.4, p < 0.0001). There was a trend to a positive correlation between SuPAR and ZBI-12 in primary caregivers, though this was not significant (correlation coefficient=0.35, p=0.12).

Healthy volunteers who identified as the primary caretaker of a patient with parkinsonism had elevated SuPAR compared to their healthy non-primary caregiver counterparts. A larger sample size should be used to explore the relationship between SuPAR and other inflammatory markers and caregiver stress in this population.