BACKGROUND: Hymenoptera venom allergy is a potentially life-threatening allergic reaction. Venom immunotherapy (VIT) is recommended to prevent severe allergic reactions. Field stings indicate the effectiveness of immunotherapy. OBJECTIVE: The aim of this study was to investigate the prevalence of venom-induced anaphylaxis, risk factors, and field sting reactions during or after the completion of VIT. METHODS: In this study, the records of patients who underwent VIT between 2015 and 2023 at one of the largest referral hospitals in Turkey were retrospectively analysed. The protocol followed during the initiation of immunotherapy, adverse reactions, clinical characteristics of the patients (including demographic characteristics, allergic diseases, laboratory findings), and field sting reactions during and after completion of immunotherapy were analysed. RESULTS: A total of 194,526 unique patient files evaluated in the Allergy Outpatient Clinic between 2015 and 2023 were analysed. Of these, 384 patients were admitted with an allergic complaint following a bee sting. Among them, 113 patients (29.4%) were eligible for VIT. A total of 79 patients were included (F/M: 41/38). VIT was performed with honeybee venom in 39 patients, vespid venom in 36 patients, and both venoms in 4 patients. 62.0% (n=49) of the patients had been stung by a bee in the head and neck region. 69.6% (n=55) of the patients had a stage 3 reaction before VIT. The cluster scheme was applied to 54.4% (n=43) of all patients. There was no statistically significant difference in the number of field stings or the use of adrenaline autoinjectors between the VIT groups (p>
0.05). Stage 3-4 reactions developed in 87.8% of patients stung in the head and neck region, compared to 53.3% of patients stung in other regions. During and after VIT, field stings were reviewed both from patient files and by follow-up inquiries during control visits. During VIT, field stings were observed in 19 patients. Systemic allergic reactions developed in 5 patients, and local allergic reactions developed in 6 patients
no allergic complaints were observed in 8 patients. After VIT was discontinued, 56 field sting reactions developed in 25 patients. Local allergic reactions developed in 9 patients, but no systemic allergic reactions were observed. Mastocytosis was diagnosed in a patient whose tryptase level was 42.4 and whose c-kit mutation was positive following haematological evaluation. CONCLUSIONS: This study confirms that the prevalence of venom-induced anaphylaxis was calculated to be 0.058%. Being stung in the head and neck region was identified as a risk factor for the development of stage 3-4 (severe allergic reactions).