Multiple inflammatory markers and 15-year incident ADL disability in admixed older adults: The Bambui-Epigen Study

Background: The ability of inflammatory markers to predict disability in later life has received growing attention. However, the current evidence came predominantly from Caucasians and the role of genomic ancestry has not been investigated.

Objective: We investigated the prognostic value of multiple citokynes and chemokines for incident disability in admixed older Brazilians and whether genomic African and Native American ancestry affects the association.

Design: Population-based longitudinal study.

Setting: The Bambui-Epigen (Brazil) Cohort Study of Aging.

Subjects: 1171 males and females aged ≥60 years over 15-year of follow-up.

Methods: Outcome examined was incident activity of daily living (ADL) disability assessed annually (10,039 measures were performed). Serum levels of citokynes (IL6, IL12, TNF, IL10, and IL1β) and chemokines (CCL2, CCL5, CXCL8, CXCL9 and CXCL10) were measured at baseline. We used 370,539 Single Nucleotide Polymorphisms (SNPs) to estimate each individual genomic ancestry proportions. Potential confounding variables included a wide range of socio-demographic variables and health indicators. Statistical analyses were based on competing risk framework.

Results: The incidence rate of disability was 57.9 per 1000 person-years. IL6 level at the highest quartile showed an independent association with ADL disability (SRH=1.32; 95% CI: 1.03, 1.70). Other inflammatory markers showed no statistically significant associations with the outcome. Neither genomic African nor Native American ancestry had an effect modifier on the associations (P for interaction >0.05 for all).

Conclusion: Among multi-inflammatory markers, only IL6 had the potential to identify people at increased risk of ADL disability, independently of ethno-racial background.