Quantification and Impact of Secondary Osteoarthritis in Patients With Anti-Citrullinated Protein Antibody-Positive Rheumatoid Arthritis

Objective. To search for evidence of secondary osteoarthritis (OA) in patients with rheumatoid arthritis (RA) in a cross-sectional and longitudinal setting, and to relate osteophyte formation to functional outcome. Methods. Anti-citrullinated protein antibody (ACPA)-positive RA patients underwent high-resolution peripheral quantitative computed tomography of the hand. Cross-sectional and longitudinal measurements were performed. The number and size (volume) of osteophytes as well as bone erosions were documented. The relationship of osteophytes to bone erosions and to demographic and disease-specific data was evaluated by multiple logistic regression models. Results. A total of 202 ACPA-positive RA patients were enrolled in the cross-sectional part of the study, and a total of 77 ACPA-positive RA patients were enrolled in the longitudinal analysis (interval of 1.5 years between baseline and follow-up assessment). The meanSD number of osteophytes per patient was 1.3 +/- 2.3, and the mean +/- SD osteophyte volume per patient was 2.6 +/- 4.9 mm(3). The total number of erosions was significantly correlated with the total number of osteophytes (P<0.001), and the total volume of erosions was significantly correlated with the total volume of osteophytes (P<0.001). Moreover, the number of osteophytes was related to age (P<0.001) and disease duration (P=0.001), while the volume of osteophytes was related to age (P=0.001), disease duration (P<0.001), and function as measured by the Health Assessment Questionnaire (P=0.013). Multivariate regression analyses showed an independent association between osteophytes and erosions. In the longitudinal analysis, the mean number (P=0.033) and volume (P<0.001) of osteophytes increased significantly in RA patients during their disease course. Conclusion. Age, disease duration, and bone erosions are associated with osteophytes, indicating development of secondary OA in patients with RA.