Associations between synovitis and radiographic osteoarthritis progression in the first carpometacarpal and interphalangeal joints: results from the Nor-Hand study.

OBJECTIVES: To determine whether baseline synovitis detected by ultrasound or MRI predicts radiographic osteoarthritis (OA) progression in the first carpometacarpal (CMC1) and interphalangeal joints. METHODS: We included 201 participants with hand OA from the Nor-Hand cohort. The CMC1 and interphalangeal joints were examined by ultrasound (both hands) and MRI (dominant hand) at baseline. Grey-scale synovitis, power Doppler activity and MRI-defined synovitis were scored on 0-3 scales. Bilateral hand radiographs at baseline and follow-up were scored by the same reader. We examined whether synovitis at baseline predicted radiographic progression in the same joint defined as ≥1 increase in Kellgren-Lawrence grade, osteophytes or joint space narrowing or incident erosions. CMC1 and interphalangeal joints were analysed separately using logistic regression with generalised estimating equations, adjusted for age, sex, body mass index and follow-up time. RESULTS: Radiographic Kellgren-Lawrence progression occurred in 14.7% of CMC1 joints and 10.2% of interphalangeal joints. Baseline grey-scale synovitis was associated with radiographic progression in the CMC1 and interphalangeal joints with the strongest observed association between grade 3 synovitis and Kellgren-Lawrence progression (OR (95% CI) of 9.3 (2.2 to 39.6) and 23.4 (10.4 to 52.9), respectively). Similar relationships were found for power Doppler activity and MRI-defined synovitis. CONCLUSIONS: Baseline synovitis detected by ultrasound and MRI was associated with radiographic progression in both CMC1 and interphalangeal joints, supporting inflammation as a relevant prognostic feature across hand OA phenotypes. TRIAL REGISTRATION NUMBER: NCT03083548.