Pos0692 Imaging and Clinical Predictors of Outcome in Chronic Periaortitis

Background: Treatment with glucocorticoids (GC), often combined with immunosuppressants, effectively induces remission in the majority of cases (75-95%) of chronic periaortitis (CP) [1]. However, a significant proportion of patients (up to 75%) experience relapses. The predictors of remission and relapse in patients with CP have never been explored. Objectives: The aim of this study was to identify predictors of remission and relapse in a large cohort of patients with CP. Methods: We retrospectively reviewed the charts of consecutive adult CP patients referred to three Italian referral centres between January 2006 and February 2021. To be included, patients were required to have baseline and post-treatment CT, 18F-FDG PET, or MRI scans, and to have undergone a 9-to-12-month treatment protocol with glucocorticoids, with or without other immunosuppressants. Statistical Analysis: Logistic univariate and multivariate regression models were employed to assess remission probability based on baseline demographic and clinical parameters. Risk of relapse, at baseline, month 4, and end of treatment (EOT), was evaluated with Cox univariate and multivariate regression models. Measurement of vascular uptake at 18F-FDG PET was graded using a 4-point (0 to 3) semiquantitative scale. Metabolic responses were classified as complete, partial, stable or progressive disease according to PERCIST criteria [2]. Remission was defined as the disappearance of disease-related symptoms, normalization of ESR and CRP and a decrease/stabilization of the mass on imaging. Relapse was defined as recurrence of disease-related symptoms or enlargement of the mass on imaging. Results: One hundred and fifteen patients, with a mean follow-up of 33 (17-57) months, were included in this study. Baseline characteristics and treatments are reported in Table 1. Of the 115 patients, 101 (87%) achieved remission, with a median time to remission of 4 (3-5) months. Among the 101 patients who achieved remission, 42 (42%) experienced a relapse, with a median time to relapse of 14 (8-26) months. Smoking habit (OR 0.34, 95% CI 0.11-0.99, p=0.049) and an atypical CP (i.e., pelvic, pre-sacral) localization (OR 0.11, 95% CI 0.02-0.52, p=0.005) were identified as negative independent predictors of remission. Conversely, PET-CT uptake at baseline (grade 0 vs grade 1-3) emerged as a positive predictor of remission (OR 11.51, 95% CI 1.35-98.20, p=0.025). In terms of predictors of relapse (Figure 1), thoracic vessel involvement and a positive 18FDG-PET at EOT were identified as positive independent predictors of relapse (HR 2.61, 95% CI 1.19-5.68, p=0.016 and HR 3.47, 95% CI 1.54-7.82, p=0.003 respectively). Conclusion: Disease activity on PET-CT at baseline emerges as an independent predictor of remission (when positive at baseline) and of relapse (when positive at EOT). Other factors are also to be considered as prognostic factors for remission (smoking and atypical CP localisation) and relapse (thoracic vessel involvement). These findings may guide treatment choices in patients with CP. REFERENCES: [1] Palmisano A et al, Curr Rheumatol Rep, 2018. [2] Wahl R et al, J Nucl Med, 2009. Table 1. Acknowledgements: NIL. Disclosure of Interests: Milena Bond Abbvie, Galapagos, Abbvie, Alessandra Bettiol: None declared, Eugenia Accorsi Buttini: None declared, Giacomo Emmi: None declared, Augusto Vaglio: None declared.