Opportunistic Screening Using Low-Dose CT and the Prevalence of Osteoporosis in China: A Nationwide, Multicenter Study.

Opportunistic screening for osteoporosis can be performed using low-dose computed tomography (LDCT) imaging obtained for other clinical indications. In this study we explored the CT-derived bone mineral density (BMD) and prevalence of osteoporosis from thoracic LDCT in a large population cohort of Chinese men and women. A total of 69,095 adults (40,733 men and 28,362 women) received a thoracic LDCT scan for the purpose of lung cancer screening between 2018 and 2019, and data were obtained for analysis from the China Biobank Project, a prospective nationwide multicenter population study. Lumbar spine (L1 -L2 ) trabecular volumetric bone mineral density (vBMD) was derived from these scans using quantitative computed tomography (QCT) software and the American College of Radiology QCT diagnostic criteria for osteoporosis were applied. Geographic regional differences in the prevalence of osteoporosis were assessed and the age-standardized, population prevalence of osteoporosis in Chinese men and women was estimated from the 2010 China census. The prevalence of osteoporosis by QCT for the Chinese population aged >50 years was 29.0% for women and 13.5% for men, equating to 49.0 million and 22.8 million, respectively. In women, this rate is comparable to estimates from dual-energy X-ray absorptiometry (DXA), but in men, the prevalence is double. Prevalence varied geographically across China, with higher rates in the southwest and lower rates in the northeast. Trabecular vBMD decreased with age in both men and women. Women had higher peak trabecular vBMD (185.4 mg/cm3 ) than men (176.6 mg/cm3 ) at age 30 to 34 years, but older women had lower trabecular vBMD (62.4 mg/cm3 ) than men (92.1 mg/cm3 ) at age 80 years. We show that LDCT-based opportunistic screening could identify large numbers of patients with low lumbar vBMD, and that future cohort studies are now required to evaluate the clinical utility of such screening in terms of fracture prevention and supporting national health economic analyses. © 2020 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR)..

CT-derived abdominal adiposity: Distributions and better predictive ability than BMI in a nationwide study of 59,429 adults in China.

BACKGROUND: Although abdominal adiposity is associated with an altered cardiometabolic risk profile, the specific contribution of abdominal adipose tissue distribution remains not fully understood. Computed tomography (CT) is a well-established and precise method to measure abdominal adipose tissue distribution. The present study investigated abdominal adiposity assessed by CT in a large-scale Chinese population. METHOD: A total of 59,429 adults who underwent a low dose chest CT for lung cancer screening at one of 13 health checkup centers throughout China were evaluated. Abdominal visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) areas were measured at the center of the 2nd lumbar vertebra with Mindways quantitative CT software using the existing CT dataset without any additional radiation exposure. The ratio of visceral to total adipose tissue (TAT) areas (VAT/TAT ratio) was calculated and expressed as a percentage. Anthropometric indices including body mass index (BMI) and waist circumference were also obtained. RESULTS: BMI, waist circumference, VAT area, SAT area, and the VAT/TAT ratio were 25.0 ±â€¯3.0 kg/m2, 90 ±â€¯8 cm, 194 ±â€¯77 cm2, 85 ±â€¯41 cm2, and 69.5 ±â€¯9.1%, respectively, in men and 23.3 ±â€¯3.1 kg/m2, 79 ±â€¯8 cm, 120 ±â€¯57 cm2, 123 ±â€¯53 cm2, and 48.9 ±â€¯9.7% in women. With increasing age, VAT area and the VAT/TAT ratio increased in both sexes whereas SAT area decreased in men (P < 0.001 for all). After adjustment for BMI and waist circumference, older individuals showed higher VAT area and higher VAT/TAT ratio than younger subjects (P < 0.001 for all). Adjusted VAT areas in participants aged 75 or older was 45 cm2 (95% confidence interval [CI]: 41 cm2, 50 cm2) higher in men and 43 cm2 (95% CI: 37 cm2, 49 cm2) higher in women compared with participants aged 31-44 years. Additionally, differences in VAT area across age groups increased as BMI or waist circumference increased. VAT and SAT areas, but not the VAT/TAT ratio, were positively associated with BMI and waist circumference in every age group. CONCLUSION: In a nationwide study conducted in China, distributions of CT-derived measures of visceral and subcutaneous adiposity were found to vary significantly between sex and age groups. Our study also revealed that the proportion of VAT (an important driver of cardiometabolic risk) could not be predicted from BMI in a Chinese population.