Association Between Diagnostic Delay and Short-Term Outcomes in Patients with Radiographic Axial Spondyloarthritis: Results from the Regisponser-AS Registry

<b>Objectives</b>: To evaluate whether the diagnostic delay in patients with radiographic axial spondyloarthritis (r-axSpA) is associated with poorer short-term outcomes after two years of follow-up. <b>Methods</b>: This was an observational, longitudinal, and prospective study including patients with r-axSpA from the national multicentre Spanish REGISPONSER-AS registry. Patients were divided into two groups according to the mean diagnostic delay (<5 years, ≥5 years). Binary logistic regression models adjusted for disease duration were constructed and used to evaluate the association between diagnostic delay and disease outcomes at two years. The retention rate for first-line treatment with anti-TNF across the groups was evaluated using a log-rank test. <b>Results:</b> A total of 565 patents were included. The mean diagnostic delay was 5.6 ± 6.2 years, with 325 patients experiencing a delay of <5 years and 240 patients experiencing a delay of ≥5 years. A diagnostic delay of ≥5 years was associated, after 2 years, with a higher prevalence of inflammatory bowel disease (IBD) (OR 2.01 (95%CI 1.06-3.83)), a lower prevalence of synovitis (OR 0.68 (95%CI 0.47-0.98)) and dactylitis (OR 0.24 (95%CI 0.11-0.55)), and worse disease activity after adjusting by disease duration. However, no impact was observed on quality of life, structural damage, or work disability, probably due to the short follow-up period. Finally, no differences between the groups were found with regard to the retention rate for first-line anti-TNF treatment. <b>Conclusions</b>: Diagnostic delay is associated with poorer short-term outcomes in terms of structural damage, dactylitis, and disability in patients with r-axSpA.