Osteoprotegerin as a biomarker of geriatric frailty syndrome

The lack of a univocal definition of frailty, a condition frequently found in the elderly population which is correlated with an increased risk of mortality, has prompted the search for clinical and laboratory parameters associated with this condition. Whereas OPG is a protein involved in different pathophysiological conditions including bone, vascular, immune and tumor disease and studies found a positive linear correlation between OPG and age we hypothesized that it may represent a frailty marker in the elderly. We conducted an observational study of 172 elderly subjects, with and without hip fracture, including a multidimensional geriatric evaluation and a laboratory evaluation, aimed to evaluate the association between OPG and frailty. Frailty Score was associated with FT3 and osteoprotegerin (OPG), regardless of fracture event. Excluding subjects with hip fracture, in whom the acute event had a direct effect on bone production of OPG, the Frailty Score showed a linear correlation with circulating levels of osteoprotegerin. In the elderly, an increase in osteoprotegerin levels may reflect a progressive accumulation of organ damage leading to the development of frailty. The correlation between OPG and Frailty Score found in our study points to its potential use as a biomarker for geriatric frailty syndrome.