Assessment of fracture risk in patients with axial spondyloarthritis: A case-control study using the fifth Korean National Health and Nutrition Examination Survey (KNHANES V)

Objectives: Axial spondyloarthritis (axSpA) is associated with low bone mineral density (BMD) and fractures, although the true fracture risk is unknown. The present study examined BMD and estimated the 10-year fracture risk in axSpA patients and matched controls and identified factors associated with a high fracture risk.Method: In total, 240 axSpA patients and 1200 healthy controls from the fifth Korean National Health and Nutrition Examination Survey (KNHANES V), matched using propensity scores, were included. Dual-energy X-ray absorptiometry (DXA) was used to measure lumbar spine and right femur BMD. Ten-year risks of major osteoporotic and hip fractures were calculated using the Fracture Risk Assessment Tool (FRAX) in subjects aged ≥ 40 years. Multivariate linear regression models were used to explore factors associated with the 10-year fracture risk in axSpA patients.Results: Hip and lumbar spine BMDs were lower in axSpA patients than in matched controls. Osteoporosis was present in 17% of axSpA patients and 3% of controls (p < 0.001). Low BMD was present in 22% of axSpA patients and 4% of controls aged < 50 years (p < 0.001). Ten-year major osteoporotic and hip fracture risks were significantly higher among axSpA patients. High 10-year fracture risk was observed in 10% of axSpA patients and 1.7% of controls (p = 0.003). The severity of sacroiliitis was independently associated with both major osteoporotic and hip fracture risks (p = 0.006 and 0.026, respectively).Conclusions: Patients with axSpA presented more frequently with low BMD and a higher calculated 10-year fracture risk than matched individuals. The severity of sacroiliitis was independently associated with a high 10-year fracture risk in axSpA patients.