Osteoporosis Self-Assessment Tool As a Screening Tool for Predicting Osteoporosis in Elderly Chinese Patients With Established Rheumatoid Arthritis

Osteoporosis Self-Assessment Tool for Asians (OSTA) is an indicator for assessing osteoporosis in postmenopausal women. The aim of this study was to investigate the value of OSTA index on predicting osteoporosis in elderly Chinese patients with established rheumatoid arthritis (RA). A total of 320 patients with RA and 158 normal individuals were recruited from January 2015 to October 2017. Bone mineral density (BMD) at the femur and lumbar spine was measured by dual-energy X-ray absorptiometry. RA group and control group were divided into low risk (values≥−1), medium risk (values between −4 and −1), and high risk (values ≤−4) group according to the value of OSTA index. One-way analysis of variance showed that BMD at all detected regions among the 3 groups were obviously different (p < 0.0001). Incidences of osteoporosis among different OSTA groups were 21.76% (47/216), 56.41% (44/78), and 80.77% (21/26), separately (x2 = 67.389, p < 0.0001). In RA group including premenspausal or postmenspausal female subgroup, prevalences of osteoporosis among different OSTA groups were different (p < 0.05–0.0001). We also found a positive linear correlation between OSTA index and BMD (p < 0.0001) both in RA and in control groups. Logistic regression revealed OSTA index (odds ratio = 0.734, p < 0.0001, 95% confidence interval: 0.657–0.819) was a protective factor for occurrence of RA-induced osteoporosis. OSTA had the highest discriminatory power, with an estimated Area Under Curve (AUC) of 0.750 (95% confidence interval 0.694–0.807, p < 0.0001), sensitivity of 76.9% and specificity of 66.5%. Our findings indicated that OSTA index was closely associated with BMD in RA patients, the degree of correlation was much stronger than age or BMI. OSTA index was a predictor for osteoporosis in RA, but it might have little relationship with disease status in RA.