Idiopathic anaphylactoid reactions. A clinical summary

Area of Science:

• Allergy and Immunology
• Clinical Medicine

Background:

• Anaphylactoid reactions are severe, potentially life-threatening allergic responses.
• Identifying the etiology of anaphylactoid reactions can be challenging.
• This study retrospectively evaluated patients with severe anaphylactoid reactions of unknown cause.

Purpose of the Study:

• To characterize the clinical presentation and outcomes of anaphylactoid reactions in a cohort of patients.
• To assess the effectiveness of treatments and the natural course of these reactions.
• To explore potential diagnostic challenges in determining the cause of anaphylactoid reactions.

Main Methods:

• Retrospective evaluation of 31 patients (aged 6-78 years) with anaphylactoid reactions.
• Inclusion criteria: life-threatening hypotension, wheezing/upper airway obstruction, and simultaneous angioedema/urticaria.
• Data collected on reaction severity, treatment, outcomes, and diagnostic investigations.

Main Results:

• All patients experienced severe symptoms, including hypotension and respiratory distress; 26 also had isolated angioedema/urticaria.
• Medications were effective in 16 of 18 patients; 10 reactions were self-limited.
• No deaths occurred in 210 anaphylactoid attacks over 164 patient-years; 7 patients achieved remission >1 year.
• Diagnostic tools like lab studies, food diaries, and skin tests were unhelpful in identifying etiology.

Conclusions:

• Anaphylactoid reactions, while severe, can be effectively managed with medications or may be self-limiting.
• The etiology of these reactions often remains elusive despite thorough investigation.
• Long-term remission is possible, and the prognosis appears favorable with no reported mortality in this cohort.