Clinical Determinants and Perioperative Allergic Reactions (CADECAP Study)

The clinical presentation of perioperative allergic and non-allergic clinical reactions is often considered undistinguishable while the accurate analysis of clinical cases shows striking clinical differences which might be predictive of the etiological diagnosis (allergic versus non-allergic).

The four-step Ring and Messmer clinical scale helps to guide acute management of immediate hypersensitivity accordingly to the clinical presentation although this scale does not take into account the mechanism involved (i.e. allergic versus non-allergic). Non-allergic clinical reactions are usually non-life-threatening and may, sometimes, spontaneously resolve in contrast to allergic reactions which are mainly severe and life-threatening conditions, typically called anaphylaxis.

The cornerstones of anaphylaxis management are fluid therapy and epinephrine. However, poor outcome has been reported as a result of delayed treatment and/or inappropriate management of perioperative anaphylaxis.

The main objectives of this study are to: i) characterize the clinical and paraclinical determinants of IgE-mediated allergy that could be correlated to the ultimate diagnosis; and ii) elaborate a decision-making algorithm for clinical patterns identification of perioperative allergic reactions to guide acute management, thus potentially decreasing the related morbidity and mortality.

The secondary objectives are to: i) suggest a modification of the Ring and Messmer scale according to the phenotypes involved; ii) identify the clinical characteristics of isolated non-allergic bronchospasm; iii) compare the most frequent agents involved in perioperative IgE-mediated allergy to those reported in the international studies; iv) identify the negative predictive values of skin tests in allergic and non-allergic patients; v) compare the therapeutic modalities used to those recommended in the literature; vi) describe the cases of morbidity and mortality and identify the potential risk factors.

The Ring and Messmer scale is used to quote the clinical features occurring in drug- or latex-induced immediate hypersensitivity and has been adapted to the perioperative setting as follows:

Grade I: Muco-cutaneous signs only (generalized erythema and/or extensive urticaria and/or angioedema) Grade II: Mucocutaneous signs, hypotension, tachycardia and/or moderate bronchospasm Grade III: Mucocutaneous signs, cardiovascular collapse, tachycardia or bradycardia, bronchospasm, digestive signs Grade IV: Cardiac arrest Grade V: Death

Perioperative immediate hypersensitivity reaction requires further allergologic assessment.

The allergologic assessment is performed a few weeks after the reaction to confirm or disprove an allergic mechanism behind the reaction (i.e. allergy versus non-allergy), and to identify culprit agent(s) and safe drugs, including suitable alternatives. It is based on the review of the details of the reaction along with histamine and/or tryptase levels and specific Immunoglobulin E levels (when available) and skin tests results.

Plasma histamine and/or tryptase levels and Immunoglobulin E levels are measured at the time of the reaction. Acute tryptase levels are compared to baseline tryptase measured at least 24 hours after the reaction or when the patient is referred for allergological investigation. Skin tests, including prick-tests and intradermal tests, are performed during the allergological assessment.

Eligibility Criteria:
Inclusion criteria:

* Patients having experienced a perioperative immediate hypersensitivity (including the obstetrical setting) according to one grade of the Ring and Messmer clinical scale, for whom:
* The clinical history is known and has been related to perioperative immediate hypersensitivity;
* The biological assessment including plasma histamine and/or tryptase (and serum IgE when available) was performed after the onset of immediate hypersensitivity according to current guidelines;
* The allergological assessment including skin tests performed by the collaborators of this study was carried out according to current guidelines in surviving patients

Exclusion criteria:

• Patients who decline to be involved in the study