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Background: Patients with rheumatoid arthritis (RA) are at increased risk of fractures. Although their decline in bone mineral density (BMD) is well-established, data regarding the alterations in bone microarchitecture are limited. In this study, we aimed to evaluate bone microarchitecture, geometry, and volumetric BMD among patients with RA in mainland China using high-resolution peripheral quantitative computed tomography (HRpQCT)., Methods: In this cross-sectional study, patients with RA were recruited from the Peking Union Medical College Hospital site of the Chinese Registry of rhEumatoiD arthrITis (CREDIT). Each participant underwent HRpQCT scanning (Scanco XtremeCT II), thoracolumbar X-ray and dual-energy X-ray absorptiometry. The primary outcomes were HRpQCT-related measures at distal radius and tibia. Data regarding demographic features, RA-related characteristics, and history of fragility fractures were collected. Correlation between HRpQCT parameters and potentially related factors were analyzed using linear regression analysis. A group of age- and sex-matched healthy controls was included for comparison., Results: A total of 81 patients with RA [69 women, aged 57.9 ± 8.7 years, disease duration 5.7 (IQR 1.4-11.2) years] and 81 matched healthy controls were included. Compared with controls, patients with RA had significantly larger bone area and lower total and trabecular vBMD at both the distal radius and tibia. Lower cortical bone thickness was also shown at the distal tibia. Among patients with RA, advanced age, low BMI, female sex, disease duration, and activity were associated with decreased vBMD and impaired bone microstructure. Female reproductive factors including menopause, late menarche, breast feeding, and early childbirth also showed negative correlation with these parameters. Compared to patients with RA without fractures, patients with fragility fractures (n = 11) showed lower trabecular and cortical vBMD, thinner cortical bone, impaired trabecular microstructure, and a trend of declined bone strength. Current glucocorticoid intake was related to decreased vBMD, trabecular number, increased trabecular separation, and inhomogeneity., Conclusions: In this study, we observed alterations in bone mineral density, geometry, and microarchitecture among patients with RA compared to healthy individuals, which may impair bone strength and lead to increased risk of fractures. Both traditional risk factors for osteoporosis and RA-associated factors need to be considered in the assessment of the bone quality.

High-resolution peripheral quantitative computed tomography (HR-pQCT) is an advanced 3D imaging technology that has the potential to contribute to fracture risk assessment and early diagnosis of osteoporosis. However, to date no studies have sought to establish normative reference ranges for HR-pQCT measures among individuals from the Chinese mainland, significantly restricting its use. In this study, we collected HR-pQCT scans from 863 healthy Chinese men and women aged 20 to 80 years using the latest-generation scanner (Scanco XtremeCT II, Scanco Medical AG, Brüttisellen, Switzerland). Parameters including volumetric bone mineral density, bone geometry, bone microarchitecture, and bone strength were evaluated. Age-, site-, and sex-specific centile curves were established using generalized additive models for location, scale, and shape with age as the only explanatory variable. Based on established models, age-related variations for different parameters were also quantified. For clinical purposes, the expected values of HR-pQCT parameters for a defined age and a defined percentile or Z-score were provided. We found that the majority of trabecular and bone strength parameters reached their peak at 20 years of age, regardless of sex and site, then declined steadily thereafter. However, most of the cortical bone loss was observed after the age of 50 years. Among the measures, cortical porosity changed most dramatically, and overall, changes were more notable at the radius than the tibia and among women compared with men. Establishing such normative HR-pQCT reference data will provide an important basis for clinical and research applications in mainland China aimed at elucidating microstructural bone damage driven by different disease states or nutritional status. © 2020 American Society for Bone and Mineral Research., (© 2020 American Society for Bone and Mineral Research.)

Asian women have lower rates of hip and forearm fractures compared to other racial groups despite lower areal bone mineral density (aBMD). We have demonstrated microarchitectural differences, including greater cortical thickness (Ct.Th) and cortical volumetric BMD (Ct.BMD), in Chinese American versus white women. Yet it is not known whether greater Ct.BMD in Chinese American women is a result of greater tissue mineral density (TMD) or reduced cortical porosity (Ct.Po). Using an advanced segmentation algorithm based on high-resolution peripheral quantitative computed tomography (HR-pQCT) images, we tested the hypothesis that Chinese American women have better cortical skeletal integrity owing to lower Ct.Po and higher Ct.TMD compared with white women. A total of 78 Chinese American women (49 premenopausal and 29 postmenopausal) and 114 white women (46 premenopausal and 68 postmenopausal) were studied. Premenopausal Chinese American versus white women had greater Ct.Th, Ct.BMD, and Ct.TMD at both the radius and tibia, and decreased Ct.Po (p < 0.05). A similar pattern was observed between postmenopausal Chinese American and white women. As expected, postmenopausal versus premenopausal women had lower Ct.BMD at the radius and tibia in both races (p < 0.001). Ct.Po largely increased between premenopausal and postmenopausal women, whereas Ct.TMD decreased by 3% to 8% (p < 0.001) in both races. Age-related differences in Ct.Po and Ct.TMD did not differ by race. In summary, both reduced Ct.Po and greater Ct.TMD explain higher Ct.BMD in Chinese American versus white women. Thicker and preserved cortical bone structure in Chinese American women may contribute to greater resistance to fracture compared to white women., (© 2014 American Society for Bone and Mineral Research.)