High-Density Lipoprotein Cholesterol and Objective Measures of Lower Extremity Performance in Older Nondisabled Persons: The InChianti Study

A low level of high-density lipoprotein cholesterol (HDL-C) is an important risk factor for atherosclerosis and its clinical complications.1 The importance of HDL as a risk factor for cardiovascular disease and mortality has been further emphasized in the older population, where HDL-C level may have better predictive value than other lipid risk factors.2,3 More recently, the prognostic value of HDL-C levels has been expanded to other common conditions of older people, suggesting that HDL-C may have further clinical relevance in addition to the inverse relationship with atherosclerosis.4 For example, low HDL-C combined with low serum albumin identified older persons with the highest risk of all-cause and noncardiovascular mortality.5 Low HDL-C has been correlated with cognitive impairment and dementia, and at least part of the association might be independent of atherosclerotic disease.6 Furthermore, there is initial evidence that values of HDL-C are inversely correlated with physical disability and motor performance.7 The ability to remain mobile is an essential aspect of quality of life and is critical for the preservation of independence in old age. Objective measures of lower extremity function, including walking speed and muscle strength, are strong predictors of severe disability, hospitalization, institutionalization, and death.8–11 Causes of impaired mobility and lower extremity function that are potentially modifiable include a number of sociodemographic and behavioral characteristics, acute and chronic diseases,12 and several metabolic conditions, including obesity, diabetes mellitus and insulin resistance, a chronic low-grade inflammatory state,13 and a high level of oxidative stress.14 HDL-C is inversely correlated with most of the above-mentioned conditions, and recent studies have reported an antiinflammatory and antioxidant effect of Apolipoprotein A-I–containing lipoproteins,15 suggesting that, through these biological activities, HDL-C may counteract the disablement process in older persons.16 The aim of this study was therefore to evaluate the independent association between HDL-C levels and different objective measures of lower extremity performance in a sample of community-dwelling nondisabled older persons. It was hypothesized that subjects with higher HDL-C levels would have better physical performance, and the study sought to assess the direct and indirect contribution of several clinical and biochemical characteristics correlated with HDL-C levels in explaining the relationship between HDL-C and physical performance.