OSTA for DXA prioritization: US-Korean imaging validation and hip-fracture follow-up in China

Population ageing is increasing demand for osteoporosis assessment, yet access to dual-energy X-ray absorptiometry (DXA) remains uneven. The Osteoporosis Self-assessment Tool for Asians (OSTA) may help prioritize access. To evaluate OSTA ranking, referral workload, and age-specific detection, with separate hip-fracture follow-up in China. We analyzed women aged 50–79 years in US/Korean DXA surveys and the China Health and Retirement Longitudinal Study (CHARLS). Survey-weighted analyses assessed femoral-neck osteoporosis using a common US T-score reference; 1,000 cluster bootstrap replicates quantified discrimination and referral uncertainty, including paired allocation contrasts. Community-cluster Cox and competing-risk models assessed self-reported hip fracture. External areas under the curve were 0.754–0.831. A US threshold targeting 20% referral selected 50.9% and 53.4% in Korea, or 48.7% and 49.4% after age standardization. Pooled target percentiles fixed referral at 20%, but sensitivity at ages 50–59 was 4.6% in both Korean periods. Age-specific allocation reduced overall sensitivity from 52.1% to 34.6% and 50.9% to 39.3%. CHARLS recorded 223 fractures during a median follow-up of 9 years; the highest-risk 20% captured 29.1% of events (adjusted hazard ratio 1.70, 95% confidence interval 1.26–2.29). Controlling workload did not preserve age-specific detection. CHARLS had no DXA data; femoral-neck osteoporosis was not verified in Chinese women. Percentile allocation requires prospective evaluation rather than stand-alone clinical adoption. The CHARLS associations do not establish prognostic information independent of age and weight.