Supplementary Material for: THE RELATIONSHIP BETWEEN SURGICAL PROCEDURES AND ANGIOEDEMA ATTACKS IN HEREDITARY ANGIOEDEMA

Introduction: Surgical interventions can trigger angioedema attacks in hereditary angioedema (HAE). The aim of this study was to assess the incidence of perioperative angioedema and identify associated risk factors. Methods: This retrospective study included HAE patients diagnosed between 1999 and 2024 at a tertiary adult allergy clinic. Data on surgical procedures and perioperative angioedema were analyzed. Results: Of 102 HAE patients, 28 were excluded due to incomplete data, leaving 74 patients (46 female, 62.2%). Fifty-three patients underwent 94 surgeries, with the most common being gynecological (27, 28.7%), abdominal (27, 28.7%), and otorhinolaryngological (16, 17.0%). Of 54 surgeries before HAE diagnosis, 23 (42.5%) were abdominal. Among 27 abdominal surgeries, 17 (62.9%) occurred in patients with gastrointestinal angioedema prior to diagnosis. Of 40 surgeries after diagnosis, 31 (77.5%) received preoperative short term prophylaxis (STP), mostly plasma-derived C1 esterase inhibitor concentrate (27, 87.1%). Perioperative angioedema occurred in 28 (29.8%) surgeries, with a median recovery of 48 hours. In surgeries after diagnosis, attacks occurred in 7 out of 31 surgeries (22.6%) with STP and 2 out of 9 (22.2%) without. Among gynecological surgeries, 22 cesarean sections were performed. No significant difference in attack frequency was found between cesarean sections with STP (3, 27.3%) and without (2, 18.2%, p=0.611). Conclusion: Our study found that abdominal attacks before HAE diagnosis are consistent with literature, underscoring their importance for early diagnosis. The angioedema rate was similar with or without STP before cesarean section, suggesting STP may not be necessary. Further research is needed to optimize HAE management in surgery.