This study aimed to evaluate the prognostic value of inflammatory biomarkers in adult patients with dural arteriovenous fistulas (DAVFs) undergoing endovascular treatment.In this retrospective study, 471 adult DAVF patients treated with endovascular therapy were included. Neutrophil-to-lymphocyte ratio (NLR), systemic inflammation response index (SIRI), and systemic immune-inflammation index (SII) were measured on admission. Poor outcome was defined as modified Rankin Scale (mRS) >2 at last follow-up. Aggressive clinical presentation (intracranial hemorrhage or non-hemorrhagic neurological deficits) and treatment-related variables were compared across outcome groups. Propensity score matching (PSM), multivariable logistic regression, subgroup analysis, and mediation models were used to validate findings.Of 471 eligible patients, 44 had poor outcomes (mRS >2) after treatment. Multivariable analysis revealed that elevated NLR, SIRI, and SII were significantly associated with poor prognosis, with odds ratios of 1.56, 1.29, and 1.28, respectively. Subgroup analyses demonstrated consistent prognostic impact of NLR, SIRI, and SII. Patients with aggressive clinical presentations exhibited significantly higher inflammation markers. The poor prognosis group had more staged treatments and hemorrhagic complications. However, mediation analysis showed no significant indirect effects through these variables, suggesting that inflammation may be directly associated with poor prognosis.Elevated NLR, SIRI, and SII on admission are associated with poor prognosis in DAVF patients. Future prospective studies incorporating serial biomarker monitoring and angiographic follow-up are warranted to validate these findings and clarify potential causal mechanisms.© Author(s) (or their employer(s)) 2025. No commercial re-use. See rights and permissions. Published by BMJ Group.