Educational level and chronic inflammation in the elderly--the role of obesity: results from the population-based CARLA study.

ABSTRACT

This study aimed to assess the mediating role of anthropometric parameters in the relation of education and inflammation in the elderly. Cross-sectional data from the population-based CARdio-vascular Disease, Living and Ageing in Halle study were used after excluding subjects with a plasma level of high-sensitive C-reactive protein (hsCRP) above 10 mg L(-1) (916 men/760 women remaining). Education was categorized in accordance with International Standard Classification of Education. As inflammation parameters, the soluble tumour necrosis factor type 1 (sTNF-R1), hsCRP and interleukin 6 (IL-6) were taken into account. Anthropometric parameters were the body mass index (BMI), waist-to-hip ratio (WHR) and waist-to-height ratio (WHeR). We used covariate adjusted mixed models to assess associations. Effect measures were the natural indirect effect (NIE), controlled direct effect and total effect (TE). Education was associated with sTNF-R1, hsCRP and IL-6 in men, and sTNF-R1 and hsCRP in women. Anthropometric parameters correlated with all inflammation parameters after covariate adjustment. BMI and WHeR were strong mediators of educational differences in sTNF-R1 (percentage of NIE of TE 28% in men; 33% in women) and hsCRP (percentage of NIE of TE 35% in men; 52% in women), while WHR was the weakest mediator. General obesity mediates roughly one-third of the association of education with chronic inflammation in the elderly.