Choroidal thickness as a biomarker of inflammatory activity in patients with polymyalgia rheumatica receiving anti-IL-6 treatment.

Objective: In corticosteroid-dependent polymyalgia rheumatica (PMR), anti-interleukin-6 (IL-6) therapies are frequently used; however, they may limit the reliability of acute-phase reactants (APRs) as biomarkers of disease activity. Choroidal thickness (CT) may serve as an alternative inflammatory biomarker in these patients. So, the aim of this study is to evaluate changes in CT in patients with PMR initiating anti-IL-6 therapy over 6 months follow-up period, and to assess its correlation and level of agreement with other inflammatory parameters. Methods: It is a prospective, observational, longitudinal pilot study. We included 24 patients with PMR who initiated anti-IL-6 therapy. Assessments were performed at baseline (treatment initiation), and at 1 and 6 months. Each visit included a physical examination, musculoskeletal ultrasound of the shoulders and hips, blood tests (including C-reactive protein [CRP]), and CT measurement by optical coherence tomography (OCT). Disease activity was assessed using the PMR Activity Score (PMR-AS) and its imputed version (PMR-ASimp). Results: Mean baseline CT was 214 ± 71.13 μm. CT decreased significantly at 1 and 6 months after treatment initiation (208.46 ± 70.03 μm, Conclusion: In patients with active PMR, CT was increased at baseline and decreased significantly following initiation of anti-IL-6 therapy. Agreement between changes in CT and changes in CRP and PMR indices was high. These findings suggest that CT may be useful as a potential inflammatory biomarker in PMR, although further studies are needed to confirm this hypothesis.