Comparison of predictive value of FRAX, trabecular bone score, and bone mineral density for vertebral fractures in systemic sclerosis: A cross-sectional study

Assessing fracture risk is important for managing patients with systemic sclerosis (SSc). Vertebral fracture (VF) is the most common fracture and is associated with future VF and non-VF. We aimed to evaluate the predictive value of FRAX, trabecular bone score (TBS), and bone mineral density (BMD) for VFs, compared to rheumatoid arthritis (RA) patients and postmenopausal women, and to identify risk factors for VFs in SSc. In this cross-sectional study, prevalent VFs, 10-year probability of major osteoporotic fracture by FRAX (FRAX-MOF), TBS, and BMD were assessed in women with SSc (n = 69) and RA (n = 58), and postmenopausal women (n = 38). Risk factors for osteoporosis, modified Rodnan total skin score (mRSS), organ involvement, and patterns of nailfold capillaroscopy (NFC) were also evaluated. The accuracy of BMD (T-score <= -2.5), TBS and FRAX-MOF, with and without TBS adjustment, to detect prevalent VF was assessed by determining the area under the receiver operating characteristic (ROC) curve. Patients with SSc (14.5%) and RA (17.2%) had significantly more VFs than postmenopausal women (0%) (P = .031). Non-significant differences were observed in TBS and BMD of all groups. The FRAX-MOF were higher in RA (9.2%) than SSc group (6.1%) and postmenopausal women (5.5%) (P < .001). Based on the ROC curve, TBS-adjusted FRAX-MOF (0.803) showed largest area under curve (AUC) to detect the prevalent VFs, followed by FRAX-MOF (0.796), TBS (0.765), and BMD (0.588) in the SSc group. In the RA group, FRAX-MOF had the largest AUC (0.896), followed by TBS-adjusted FRAX-MOF (0.863), TBS (0.736), and BMD (0.686). The cutoffs for FRAX-MOF and TBS-adjusted FRAX-MOF for detecting VFs were 8.95% and 9.7% for SSc, and 14.5% and 14% for RA. No association between VFs and SSc subtypes, organ involvement, mRSS or NFC patterns was found. FRAX-MOF, with or without TBS, had better predictive value for VFs than BMD and TBS in SSc. However, FRAX-MOF underestimated the probability of VFs in SSc compared with RA.