Discordance in bone mineral density between lumbar spine and hip in patients with rheumatoid arthritis: A cross-sectional study.

Objectives: Osteoporosis is a common comorbidity in patients with rheumatoid arthritis (RA). In this study, we investigated the discordance in T-scores between the lumbar spine and hip in patients with RA. Methods: This cross-sectional study included 520 patients with RA with T-scores for the lumbar spine, total hip, and femoral neck. T-score discordance was defined as differences in the WHO T-score categories between the spine and femur. Major discordance indicated osteoporosis at one site and a normal T-score at the other, whereas minor discordance represented a one-category difference. Discordance was also defined as a ≥1.5 difference in T-scores between the two sites. Results: A comparison of the major, minor, and no discordance groups regarding T-scores of the lumbar spine and hip identified significant variables, including age (P < 0.001), body mass index (P = 0.008), duration of RA (P = 0.001), Health Assessment Questionnaire Disability Index (P < 0.001), pharmacotherapy for osteoporosis (P < 0.001), scoliosis (P = 0.006), and vertebral fracture (P = 0.030). Analysis of the presence or absence of a discordance ≥1.5 in T-scores between the lumbar spine and hip, showed that age (P = 0.010), sex (P < 0.001), duration of RA (P = 0.033), and type 2 diabetes mellitus (P = 0.034) were associated with discordance. Conclusions: This study identified factors associated with discordance in bone mineral density between the lumbar spine and hip in patients with RA, highlighting the need for careful interpretation of site-specific measurements, particularly in high-risk patients.