4CPS-093 Analysis of the impact of the omalizumab shortage in the allergy department

<h3>Background and Importance</h3> Omalizumab is a humanised monoclonal antibody that selectively binds to human immunoglobulin E (IgE) preventing its binding to Fcε in basophils and mast cells, reducing the amount of free IgE available to trigger the allergic cascade. <h3>Aim and Objectives</h3> Analyse the impact of the omalizumab shortage on the allergy department (AP), and measures taken to control it. <h3>Material and Methods</h3> This retrospective study included patients treated with omalizumab prescribed by the AP who needed to be dispensed during the stock-out period (July-September 2024). The variables included were: diagnosis, presence of exacerbations during treatment, initial dose, cost of treatment, therapeutic approach taken (maintaining the regimen, reducing or spacing the dose, changing to another biologic drug, or discontinuation), final dose and cost of the new therapy. <h3>Results</h3> Seventy-one patients were on treatment with omalizumab, 51/71 required medication during the study period. 33/51 had chronic spontaneous urticaria, 14 had severe asthma and 4 were used off-label. Most patients were controlled on omalizumab treatment, except for 4 patients with urticaria and 1 with asthma, who presented exacerbations. Prior to the shortage, 25 patients used the dose indicated in the technical sheet, 23 had a lower dose and/or longer interval, and 3 had been administered a higher dose or shorter interval. Prior to the shortage, the total annual cost was 320.609,5 euros, and the average annual cost was 5874,2 euros/patient. Regarding the therapeutic attitude, in 16 patients the therapeutic interval (TI) was increased by 1–2 weeks (TI between C/5 and C/16 weeks), in 11 it remained the same, in 10 it was necessary to change the biologic drug (4 to dupilumab, 1 to benralizumab, 2 to mepolizumab and 3 to tezepelumab), 8 discontinued treatment and 6 reduced the dose by half (150mg). Finally, the total annual cost was 245.371 euros, and the average cost was 5203,2 euros/patient. <h3>Conclusion and Relevance</h3> Stock-outs are a therapeutic challenge for the multidisciplinary team caring for thepatient. Furthermore, these stock-outs have made it possible to re-evaluate treatmentsand optimise therapy, either by substituting more efficient drugs or by discontinuing them. <h3>References and/or Acknowledgements</h3> <h3>Conflict of Interest</h3> No conflict of interest