International Rhinologic Society Rhinology 0300-0729 2025 11 30 Olfactory outcomes following biological therapy in chronic rhinosinusitis: a systematic review and meta-analysis EN D. Patel Luton and Dunstable Hospital, Bedfordshire Hospitals NHS Foundation Trust, Luton, UK J.S. Morris University Hospital of Wales, Cardiff and Vale Health Board, Cardiff, Wales, UK V. Acharya Royal National ENT and Eastman Dental Hospitals, University College London Hospitals NHS Foundation Trust, London, UK P. Andrews Royal National ENT and Eastman Dental Hospitals, University College London Hospitals NHS Foundation Trust, London, UK Journal Article 3342 10.4193/Rhin24.573 Background: Anosmia is a common, debilitating, and often treatment-resistant symptom of CRS. Biological therapies are a novel and promising treatment for severe and uncontrolled CRS, however, the impact of biological therapy specifically on olfatory dysfunction has not yet been evaluated through systematic review. Methodology: Systematic searches of Ovid MEDLINE, EMBASE and Cochrane Library were performed on 25/05/2024, assessing olfactory outcomes following treatment with biologics. Random-effects meta-analyses were conducted to generate restricted maximum-likelihood estimates for the absolute improvement in each outcome of interest. Results: Systematic searches yielded 801 papers, of which 37 studies comprising of 3284 patients treated with biologics and 1138 controls. In the RCT-only analysis, biologics conferred significat improvements versus control in UPSIT and VAS olfaction (measured as a 0-10 Likert scale). Across all papers, Dupilumab showed significat improvements versus Omalizumab in UPSIT and VAS. Conclusions: Biological therapies are effective in improving olfactory dysfunction secondary to treatment-resistant CRS, with VAS olfaction gains being demonstrated up to 12 months after treatment. Dupilumab shows initial promise over omalizumab; however, cost-effectiveness of biological therapies may limit widespread clinical usage currently.