Respiratory function as a marker of bone health and fracture risk in an older population

Identification of those at high risk of osteoporosis and fractures using clinically available tests beyond BMD measures is a major clinical challenge. We examined forced expiratory volume in 1 s (FEV1), an easily obtainable measure of respiratory function, as a clinical measure for fracture prediction. In the context of the European Prospective Investigation into Cancer-Norfolk Study, 8304 women and 6496 men 42-81 yr of age underwent a health check including spirometry and heel quantitative ultrasonography between 1997 and 2000 and were followed up for incident hip fractures until 2007. The main outcome measures were broadband ultrasound attenuation (BUA) of the heel (cross-sectional analysis) and hip fracture risk (prospective analysis). In multivariate regression models, a 1-liter increase in FEV1 was associated with a statistically significant 2.2-dB/MHz increase in BUA, independent of age, smoking, height, body mass index, history of fracture, and use of corticosteroids. Mean FEV1 was significantly lower among 84 women and 36 men with hip fracture compared with other participants. In multivariate proportional-hazard regression models, the relative risk (RR) of hip fracture associated with a 1-liter increase in FEV1 was 0.5 (95% CI, 0.3-0.9; p < 0.001) for both men and women. RR of hip fracture for a 1 SD increase in FEV1 was approximately equivalent to a 0.5 SD increase in BUA among women (1 SD among men) and an 5-yr decrease in age among both men and women. Middle-aged and older people with low respiratory function are at increased risk of osteoporosis and hip fracture. FEV1, an easy, low-cost, and feasible clinical measure, may help improve the identification of high-risk groups.