Bone changes assessed with High-Resolution peripheral Quantitative Computed Tomography (HR-pQCT) in early inflammatory arthritis: a 12-month cohort study

Abstract

Objectives: We sought to determine the sensitivity of high resolution peripheral quantitative computed tomography (HR-pQCT) to detect change and identify erosions in comparison with conventional radiography (CR) in early inflammatory arthritis patients. We also explored which prognostic factors contribute to bone damage assessed by HR-pQCT in the first year of diagnosis. Methods: 46 patients with arthritic symptoms less than one year, and a clinical diagnosis of inflammatory arthritis were prospectively imaged at baseline and 12-months. HR-pQCT scans of the 2nd and 3rd MCP joints and CR of the hands and feet were performed. Joint space width (JSW), total bone mineral density (Tt.BMD), erosion presence and volume were assessed with HR-pQCT. Scan-rescan precision was assessed to define an individual-level least significant change (LSC) criterion. Regression analyses explored prognostic factors for bone damage progression. Results: We observed no significant group-level changes in JSW, Tt.BMD or erosion volume. 20% or fewer joints demonstrated individual-level changes greater than the LSC criterion for mean JSW, Tt.BMD and erosion volume. HR-pQCT detected more erosions than CR in the 2nd and 3rd MCP. Increased symptom duration at diagnosis was associated (p < 0.10) with lower JSW minimum and higher JSW standard deviation. Conclusions: We have demonstrated stability in erosion, bone density and JSW over 12-months in most patients receiving treatment for inflammatory arthritis using a LSC criterion, although patients with longer symptom duration prior to treatment initiation had demonstrable negative effects on JSW estimates. HR-pQCT captures bone damage and progression undetectable by CR in the imaged joints.