Dynamic vascular changes on long-term ultrasound monitoring predict relapse in large-vessel giant cell arteritis.

BACKGROUND: Color duplex ultrasound (CDUS) is increasingly used to assess disease activity in large-vessel giant cell arteritis (LV-GCA), but its role in long-term monitoring and relapse prediction remains unclear. We aimed to evaluate dynamic changes in ultrasound findings during follow-up and their prognostic value for relapse. METHODS: In this retrospective longitudinal study, 43 newly diagnosed LV-GCA patients from a fast-track clinic underwent serial color duplex ultrasound (CDUS) of temporal, axillary, subclavian, and carotid arteries during follow-up. Several semiquantitative ultrasound indices were assessed. The validated OMERACT GCA Ultrasonography Score (OGUS) included temporal and axillary arteries, while two extended indices, OGUS-10LV and OGUS-12LV, were specifically developed for this study to include subclavian and carotid arteries, respectively. Halo count indices (HC8, HC10, HC12) represented the number of arteries showing a halo sign. Patients were stratified by relapse status, and the predictive value of early ultrasound changes was tested using receiver operating characteristic (ROC) analysis. RESULTS: Relapse occurred in 26 of 43 patients (60.5%), within 24 months (mean 10.2 ± 5.7). Non-relapsing patients showed progressive OGUS indices reductions, with differences at 9 months for OGUS and 6 months for OGUS-10LV/12LV. Values < 1 from month 6 were consistently observed only in non-relapsing patients. HC normalization (no halo in any arteries) occurred earlier in non-relapsing patients (HC8: 18 vs. 24 months; HC10: 18 vs. 30; HC12: 36 vs. not reached). ROC analysis identified ΔOGUS-12LV ≤ 0.07 at 6 months as the optimal cutoff for predicting relapse at 12 months (AUC 0.944). CONCLUSIONS: OGUS and its extended variants demonstrate sensitivity to change and prognostic value in LV-GCA. Early dynamic changes predict relapse, while delayed HC normalization characterizes relapsing patients. These findings support imaging remission as a meaningful endpoint and CDUS as a biomarker for individualized monitoring.