Partial bone erosion repair is independently associated with functional improvement in early rheumatoid arthritis: a 2-year prospective high-resolution peripheral quantitative CT (HR-pQCT) longitudinal study
Qihan Wu, Sze-Lok Lau, Isaac T Cheng, Tin Yuet Chan, James Griffith, Yan Kitty Kwok, Jack JW Lee, Ka Lai Violet Lee, Ling Qin, Vivian Hung, Chun Kwok Wong, Cheuk Wan Isaac Yim, King Yee Shirley Ying, Wei-Chuan Yu, Ho So, Lai-Shan TamObjective
To determine whether change in bone erosion volume detected by high-resolution peripheral quantitative CT (HR-pQCT) is independently associated with functional outcome in early rheumatoid arthritis (ERA).
Methods
In this prospective study, 101 patients with ERA received 2-year tight-control treatment aiming at Simplified Disease Activity Index (SDAI) remission (SDAI ≤3.3). HR-pQCT of the second to fourth metacarpophalangeal joints was performed at baseline and at month 24 to quantify erosion parameters. Partial erosion repair was defined as a reduction of at least one erosion count or a decrease in total erosion volume exceeding the least significant change; progression was defined conversely. Functional status was assessed using the Health Assessment Questionnaire-Disability Index (HAQ-DI).
Results
After 2 years, disease activity and HAQ-DI improved significantly (all p<0.001) in paired analyses (n=98). Sixteen (16.3%) patients showed partial erosion repair and 38 (38.8%) erosion progression. In the partial erosion repair group, reduction in total erosion volume correlated strongly with HAQ-DI improvement (ρ=0.719, p=0.003). This association remained significant in linear regression analyses (β=0.607, p=0.003) independent of the contribution from change in SDAI (β=0.453, p=0.018). By contrast, among erosion progressors, change in HAQ-DI was primarily driven by improvement in SDAI (β=0.755, p<0.001). Baseline swollen joint count was associated with erosion progression in univariate analysis (OR 1.177, 95% CI 1.026 to 1.349, p=0.020) and after adjustment for sex (OR 1.171, 95% CI 1.019 to 1.346, p=0.026).
Conclusion
HR-pQCT-detected partial repair of bone erosion was independently associated with functional improvement beyond inflammation control.