Clinical and laboratory predictors of diagnostic delay in childhood Takayasu arteritis and polyarteritis nodosa: a retrospective cohort study

Objectives Due to their non-specific clinical presentation and low prevalence, diagnostic delays are common in Takayasu arteritis (TA) and childhood Polyarteritis Nodosa (cPAN), and may result in preventable organ damage. However, data on specific factors contributing to diagnostic delay in pediatric vasculitis remain limited. Objectives were to identify clinical, demographic, and laboratory predictors of diagnostic delay in children with TA or cPAN, and to determine the characteristics associated with a delay of > 30 days. Methods This retrospective cohort study included patients diagnosed with TA or cPAN at a single tertiary pediatric rheumatology center between 2010 and 2025. Demographic data, presenting symptoms, laboratory findings, and diagnostic timelines were extracted from medical records. Diagnostic delay was analyzed using non-parametric tests and logistic regression. As there is no universally accepted definition of prolonged diagnostic delay in pediatric vasculitis, this study explicitly adopted a 30-day threshold to distinguish between early and delayed diagnoses for the purpose of comparative analysis. Classification criteria from EULAR/PRINTO/PRES were used to confirm diagnoses 1. Results A total of 46 patients (67.4% female; mean age at diagnosis: 11.1 years) were included. Median diagnostic delay was 13 weeks. Using the ≥30-day threshold, 16 of the 46 patients (34.8%) met the definition of prolonged diagnostic delay. Although only one-third of patients met this criterion, the duration of delay varied widely, with several cases exceeding two to three months. Fever and fatigue were significantly associated with prolonged delay (p= 0.009 and p= 0.011, respectively). Age at diagnosis showed a significant positive correlation with delay in the cPAN subgroup. White blood cell (WBC) and platelet counts were negatively correlated with delay, particularly in TA while acute phase reactants did not have an effect. Logistic regression identified fever as the strongest independent predictor of > 30-day diagnostic delay. Conclusions Systemic symptoms such as fever and fatigue may obscure early recognition of vasculitis in children. Greater awareness and structured diagnostic approaches are needed to reduce diagnostic delays and improve outcomes in pediatric vasculitis.