Bone loss in very early inflammatory back pain in undifferentiated spondyloarthropathy: a 1-year observational study

Objective Bone loss in patients with inflammatory back pain (IBP) suspicious of early undifferentiated spondyloarthropathy is poorly defined. The aim of this study was to examine changes in bone mineral density (BMD) at the hip, lumbar spine and hand in patients with early IBP and to look for possible biomarkers associated with this change. Methods In 30 patients with early IBP, clinical data were collected and BMD assessed using dual energy x-ray absorptiometry at baseline, 6 and 12 months. Further imaging performed included MRI of the sacroiliac joints (SIJs) and spine at baseline and x-rays of the SIJs at baseline and after 8 years. Results After 12 months no significant reduction in hip, spine and hand BMD was seen at the group level. However, hip bone loss was found to be associated with raised baseline C-reactive protein levels, baseline MRI bone marrow oedema of the SIJs and the presence of radiographic sacroiliitis after 8 years. No association was found with change in spine and hand BMD. Conclusion Systemic bone loss in the hip is an early feature of the inflammatory disease process in patients with IBP in undifferentiated spondyloarthropathy and is related to disease activity. These data highlight the importance of aggressive intervention in the early stages of disease in undifferentiated spondyloarthropathy.