The Relationship Between Circulating Interleukin-6 Levels and Future Health Service Use in Dementia Caregivers

Objective Older adults are among the most frequent users of emergency departments (EDs). Nonspecific symptoms, such as fatigue and widespread pain, are among the most common symptoms in patients admitted at the ED. Interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-alpha) are inflammation biomarkers associated with chronic stress (i.e., dementia caregiving) and nonspecific symptoms. This study aimed to determine whether IL-6 and TNF-alpha were prospectively associated with ED risk in dementia caregivers (CGs). Methods Participants were 85 dementia CGs, who reported during three assessments (3, 9, and 15 months after enrollment) if they had visited an ED for any reason. Cox proportional hazards models were used to examine the relations between resting circulating levels of IL-6 and TNF-alpha obtained at enrollment and subsequent risk for an ED visit, adjusting for age, sex, use of ED 1 month before enrollment, physical and mental health well-being, body mass index, and CG demands. Results (log) IL-6 significantly predicted ED visits during the 15-month follow-up (B = 1.96, SE = 0.82, p = .017). For every (log) picogram per milliliter increase in IL-6, the risk of visiting an ED was 7.10 times greater. TNF-alpha was not associated with subsequent ED visits. Exploratory analyses suggested that CGs with levels of IL-6 above the 80th percentile and experiencing high CG demands were at highest risk of an ED visit. Conclusions IL-6 levels and CG demands may be useful for predicting vulnerability for future ED visits. Although further studies should be conducted to replicate and extend these findings, interventions that successfully modify inflammation markers, including the underlying pathophysiology related to stress and/or comorbid illnesses, may be useful in preventing costly and detrimental outcomes in this population.