The OMERACT Giant cell arteritis Ultrasonography Score: a potential predictive outcome to assess the risk of relapse during follow-up.

OBJECTIVE: To determine whether the OMERACT giant cell arteritis (GCA) Ultrasonography (US) Score (OGUS) change after treatment can be used for assessing the probability of relapse.

METHODS: Multicenter retrospective study of GCA patients referred to two US GCA fast-track clinics over 2 years. Patients underwent US evaluation at baseline, 3 and 6 months. EULAR definitions for remission and relapse were checked at 3 and 6 months. OGUS changes at 0-3 months and 0-6 months were compared among patients with and without relapse at 6 months, as well as those with and without remission at 6 months.

RESULTS: A total of 76 patients were included (mean age 77.2 years, 55.3% females). Nineteen (26%) patients relapsed at 6-months, of whom 14(19.1%) showed a minor relapse. EULAR remission at 6 months was achieved by 32(43.8%) patients. The standardized mean difference of OGUS between baseline and 3 and 6 months was -0.25 and -0.38, respectively. OGUS significantly improved between baseline and 6 months (1.18 vs 0.99,p=0.004) and from 3-6 months (1.08 vs 0.99,p=0.04) in non-relapsing patients, whereas no significant changes at 3 (1.17 vs 1.17;p=0.736) and 6 (1.17 vs 1.21;p=0.343) months were observed in those who experienced relapse. Mean 0-6-month OGUS improvement was lower in patients who relapsed (-0.1 vs 0.16,p=0.037). Mean 0-6-month OGUS improvement was greater in patients who achieved remission at 6 months (0.28vs -0.07,p=0.001).

CONCLUSIONS: The absence of OGUS improvement during follow-up in GCA may be used to assess the probability of relapse and the absence of remission at 6 months.