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 > or =75 years (mean age 79.8 +/- 5.2 years, 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 (beta = -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 (beta = -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 HDL-C concentrations. Though HDL-C may merely act as a wellbeing index, HDL-C concentrations should be considered in studies evaluating inflammation and physical function.