The protocol for the Prospective Urban Rural Epidemiology China Action on Spine and Hip status study.

The Prospective Urban Rural Epidemiology (PURE) China Action on Spine and Hip status (CASH) study focused on the prevalence of osteoporosis and spinal fracture in China. The aim of the PURE CASH study is to determine the prevalence of osteoporosis and spinal fracture, and explore the potential relationship between spinal fracture and bone mineral density (BMD). This study is a prospective large-scale population study with a community-based sampling and recruitment strategy. The aim is to determine the prevalence of osteoporosis and vertebral fracture in this population, to evaluate the association between vertebral fractures and BMD values, and to assess the prediction power of BMD for incident fractures. Participants in the PURE CASH study are all from the PURE study in China, recruited from 12 centers in 7 Chinese provinces. The inclusion criteria are that participants should be aged more than 40 years and able to give informed consent. Exclusion criteria are pregnant women, individuals with metal implants in the lumbar spine, use of medications or the existence of any disease or condition known to have a major influence on BMD, and inability to give informed consent. A total of 3,457 participants undergo a quantitative computed tomography (QCT) scan of the upper abdomen. The scanning parameters are as follows: 120 kVp at all centers, mAs between 75 and 200, FOV 40 cm×40 cm. The BMD values of L1 to L3 are measured, and the average BMD calculated. The American College of Radiology QCT criteria for the diagnosis of osteoporosis is applied to determine the presence of osteoporosis. The scout view images of T4-L4 vertebrae are reviewed by two experienced radiologists for semi-quantification of vertebral fractures according to Genant's method.