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

Abstract

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)..

Trial registration: ClinicalTrials.gov NCT03699228.

Keywords: BONE MINERAL DENSITY; LOW-DOSE CT; OPPORTUNISTIC SCREENING; OSTEOPOROSIS; PREVALENCE.

Fig 1

Flowchart of participants. *Data from 13 centers.

Fig 2

Measurement of vBMD of L1 and L2 with Mindways QCT Pro system. (A) Coronal view of a chest LDCT scan. (B) Positioning of sagittal and axial views for subsequent automatic placement of analysis VOIs. (C) Analysis VOIs shown as red ellipse in axial view and yellow rectangle in sagittal view. LDCT = low‐dose CT; VOI = volume of interest.

Fig 3

The mean and SD of BMD variation with age. Women had higher vBMD than men before age 50 whereas older women had lower vBMD than men.

Fig 4

Prevalence of osteoporosis in participants aged 50 years and older. The prevalence increased with age in both men and women. At age 60 years prevalence was already twice as high in women as in men and the ratio increased further at higher ages. Error bars show the 95% confidence intervals.

Fig 5

Box and whisker plots showing distributions of vBMD in men and women across different regions of China.

Fig 6

The prevalence of osteoporosis in the ≥50 years group among different regions measured by QCT. Both men and women from Central or Southwest of China had higher prevalence of osteoporosis than those from Northeast or North of China. Error bars show the 95% confidence intervals.