Sclerostin in Institutionalized Elderly Women: Associations with Quantitative Bone Ultrasound, Bone Turnover, Fractures, and Mortality

Objectives To evaluate the association between levels of circulating sclerostin (an emerging biomarker and important regulator of bone formation) and laboratory parameters of bone and mineral metabolism, bone mineral density and quality measured using quantitative ultrasound (QUS), fracture risk, and mortality. Design Prospective cohort study. Setting Austrian nursing homes (N=95). Participants Female nursing home residents aged 70 and older (mean 84 +/- 6; N=539). Measurements Serum sclerostin, bone turnover markers, and bone mineral density and quality were measured at baseline. Participants were followed for clinical fractures and all-cause mortality. Results Partial correlation analysis adjusted for age, weight, and renal function revealed a significant positive correlation between sclerostin levels and calcaneal stiffness and radial and phalangeal speed of sound (all P<.01) and a significant negative correlation between sclerostin levels and osteocalcin, serum C-terminal telopeptide of type I collagen, and parathyroid hormone (PTH; P<.05). After a mean follow-up of 27 +/- 8months, 139 participants (26%) had died and 64 had a hip or other nonvertebral fracture (12%). Sclerostin was not predictive of mortality. In women with a negative fracture history, it was significantly but not linearly associated with fracture risk. Conclusion In institutionalized elderly women, there is a significant relationship between serum sclerostin levels and QUS indices, bone turnover, and PTH, but sclerostin was not strongly associated with important clinical outcomes. Thus, it remains unclear whether sclerostin is a clinically useful predictor of fractures or mortality, at least in this setting.