Declining venom immunotherapy: patient characteristics and clinical outcomes

A largely unknown proportion of Hymenoptera venom-allergic patients do not undergo venom immunotherapy (VIT) despite positive allergy testing and counselling. We aimed to identify factors associated with the refusal of VIT, and evaluate the natural course of venom allergy in untreated individuals.

Out of 1163 candidates for VIT, 271 (23.3%) declined or postponed treatment for at least 12 months. Complete data from 166 of these patients, who were interviewed and counselled during routine follow-up, were available for retrospective evaluation.

Patients declining VIT were significantly more likely to be female (P = 0.012) and had a lower grade of index sting-induced anaphylaxis (P < 0.001) compared to those who accepted treatment. Main reasons for deciding against VIT were that it was considered too time-consuming (39.8%) or perceived as unnecessary (24.1%). A minority of patients (6.6%) declined VIT due to fear of side effects; 7.2% perceived the VIT-associated risk as high to extremely high. Most (69.9%) reported routinely carrying an epinephrine autoinjector. The re-sting rate was 39.2% over a median follow-up of 5 years. Among 65 re-exposed patients, 13 (20%) reported an anaphylactic sting-reaction, with only two cases classified as severe. In no case did a severe relapse occur following a mild index sting reaction.

In venom-allergic patients hesitant about VIT, treatment choices should be guided by a shared decision-making process considering risk factors for severe anaphylaxis and the degree of sting exposure, together with the patient's personal needs and preferences.