Interaction of HDL cholesterol concentrations on the relationship between physical function and inflammation in community-dwelling older persons

Background: the existence of a relationship among inflammation, high-density lipoprotein cholesterol (HDL-C) and physical function has been suggested. Objective: the aim of the study is to investigate the possible interaction of HDL-C on inflammation and physical function. Design: cross-sectional study. Setting: town of Tuscania (Italy). Subjects: all the 329 community-dwelling older persons aged ≥75years (mean age 79.8±5.2years, women 56.2%). Methods: HDL-C, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and interleukin-6 (IL-6) were measured. Activities of daily living (ADL), instrumental ADL (IADL) and 4-m walking speed were assessed. Linear regression models were performed. Results: given the multiple significant interactions, models were stratified according to HDL-C concentrations. In participants with normal HDL-C concentrations, only IL-6 showed a significant association with IADL (β=−0.439, SE=0.176, P= 0.01). In participants with low HDL-C concentrations, all three inflammatory biomarkers were significantly associated with 4-m walking speed and IADL. IL-6 was also significantly associated with ADL (β=−0.755, SE=0.259, P=0.006), whereas borderline significances were reported for CRP and ESR. Conclusions: the association between inflammation and physical function is particularly enhanced in elders with low HDLC concentrations. Though HDL-C may merely act as a wellbeing index, HDL-C concentrations should be considered in studies evaluating inflammation and physical function.