The Utility of Radiographic Focal Erosions of Hands or Feet in Predicting DXA-defined Osteoporosis of the Hip in Patients with Rheumatoid Arthritis

Introduction: Osteoporosis is a common comorbidity in Rheumatoid Arthritis (RA) patients and can result in estimated double risk of pathological fractures. Bone Mineral Density (BMD) is known to decrease with RA because of mechanisms incorporating traditional as well as disease-specific causes. With the advent of newer disease-modifying antirheumatic agents and bone protection medications, it is becoming important to identify those individuals who are at increased risk of developing osteoporosis among RA patients. Aim: In the current study, we aim to evaluate a multitude of factors including focal erosions on radiographs of hands or feet that can predict osteoporosis in RA patients. Methods: After obtaining IRB approval, 26 patients (20 females & 6 males) with a median age of 62 years (95% CI: 57.4 - 66.0) were retrospectively identified from a Rheumatology clinic database with an established diagnosis of RA but not taking osteoporosis medications. A detailed assessment was accomplished including evaluating a number of disease-specific variables, hands/feet radiographs and Dual-energy X-ray Absorptiometry (DXA). Results: The total hip BMD was lower in RA patients with radiographic erosions (0.862 g/cm2 ± 0.17) compared to those patients without erosions (1.011 g/cm2 ± 0.13). On univariate logistic regression, the presence of radiographic erosions predicted osteoporosis of the hip (p = 0.04). ROC curve demonstrated satisfactory performance of erosions in predicting WHO-defined osteoporosis or osteopenia at the hip (AUC = 0.732). Conclusion: RA patients who show radiographic erosions are more likely to develop hip osteoporosis that may require further intervention.