Bone erosions detected by ultrasound are prognostic for clinical arthritis development in patients with ACPA and musculoskeletal pain

BackgroundTo assess the prognostic value of ultrasound for clinical arthritis development among anti-citrullinated peptide antibody (ACPA)-positive patients with musculoskeletal (MSK) pain.MethodsWe prospectively followed 82 ACPA-positive patients with MSK pain without clinical signs of arthritis at baseline. Ultrasound examination at baseline assessed synovial hypertrophy (SH), and inflammatory activity by power Doppler (PD) in 36 small joints and 6 tendons, and erosions in 18 joints. We applied Cox regression analyses to examine associations with clinical arthritis development during follow-up (median, 69 months; range, 24–90 months). We also compared the ultrasound findings among the patients to a control group of 100 blood donors without MSK pain.ResultsClinical arthritis developed in 39/82 patients (48%) after a median of 6 months (range, 1–71 months). One or more ultrasound erosions occurred in 13/82 patients (16%), with none in control subjects (p < 0.001). Clinical arthritis development was more common among patients with baseline ultrasound erosions than those without (77% vs 42%, p = 0.032), and remained significant in a multivariable Cox regression analysis that included previously described prognostic factors (HR 3.9, 95% CI 1.6–9.4, p = 0.003). Ultrasound-detected tenosynovitis was more frequent among the patients and associated with clinical arthritis development in a univariable analysis (HR 2.5, 95% CI 1.1–5.7, p = 0.031), but did not remain statistically significant in multivariable analysis. Neither SH nor PD was associated with arthritis development.ConclusionsBone erosions detected by ultrasound are independent predictors of clinical arthritis development in an ACPA-positive at-risk population.Trial registrationRegional Ethics Committee in Linköping, Sweden, Dnr M220-09. Registered 16 December 2009, https://etikprovningsmyndigheten.se/