Original Title: Dosage des IgG4 spécifiques aux allergènes alimentaires par immunoessai

Authors' objectives: A request to include a new test in the Répertoire québécois et système de mesure des procédures de biologie médicale (hereinafter the “Répertoire”) was submitted to the Ministère de la Santé et des Services sociaux (MSSS) by the Montréal-CHUM cluster (hereinafter the “requesting laboratory”). The MSSS asked the Institut national d’excellence en santé et en services sociaux (INESSS) to assess the advisability of including specific IgG4 (immunoglobulin G4) measurement by immunoassay in the Répertoire.

Authors' results and conclusions: RESULTS (#1 POPULATIONAL DIMENSION): As many as about 3000 persons, mainly children, are being followed at Québec’s oral immunotherapy clinics. • The objectives of oral immunotherapy are first determined with the person who is being treated. For some, the objective is to acquire protection against traces of the allergen, while others will want to incorporate the food into their diet. The clinical follow-up is therefore different for each person. (#2 CLINICAL DIMENSION): In the context of oral immunotherapy, no specific IgG4 cutoff level correlating with a desensitization or tolerance status was found in the literature. The clinicians consulted point out that it is the increase in the specific IgG4 level over the baseline value that is of interest, not a specific threshold. • According to the clinicians consulted, a specific IgG4 measurement would supplement a specific IgE measurement in order to better document the immunological changes induced by this treatment, which could improve clinical decision making. In the literature, the impact of including specific IgG4 measurement in the management of persons receiving oral immunotherapy is uncertain. (#3 ORGANIZATIONAL DIMENSION): Specific IgG4 measurements would be performed on the same instrument using the same blood sample and reagents used for specific IgE measurements as well. The estimated turnaround time for specific IgG4 measurement results would be one month, which is considered acceptable, in the opinion of the clinicians consulted. (#4 SOCIOCULTURAL DIMENSION): No explicit recommendation was made regarding the use of specific IgG4 measurement in the follow-up of oral immunotherapy for treating a food allergy. One guideline states that IgG4 measurement is indicated if this test is available. Certain other guidelines identified briefly mention specific IgG4 levels but do not make any recommendations. (#5 ECONOMIC DIMENSION): Although the cost-effectiveness of specific IgG4 measurement cannot be estimated because of the lack of data for quantifying the health benefits resulting from its use, the cost associated with the test proposed by the requester is higher than no test (weighted value 19.79).

Authors' recommendations: In light of the findings presented above, INESSS recommends to the Minister that food allergenspecific IgG4 measurement by immunoassay not be included in the Répertoire québécois et système de mesure des procédures de biologie médicale.

Authors' methods: To answer the evaluation questions, a rapid scientific literature review was conducted of publications identified in bibliographic databases and other information sources. In addition, consultations were held with clinicians and other stakeholders. The methodology was applied to the five dimensions of INESSS’s framework for assessing the value of interventions. A budget impact analysis that took into account the costs associated with including specific IgG4 measurement in the Répertoire was performed. The costs were projected over a 3-year time horizon from a healthcare system perspective. All of the scientific, contextual and experiential data were interpreted and were synthesized into findings for guiding the members of the Permanent Deliberative Committee - Diagnostic Approaches and Screening in their deliberative process aimed at making the recommendation.

Project Status: Completed

URL for project: https://www.inesss.qc.ca/publications/repertoire-des-publications/publication/dosage-des-igg4-specifiques-aux-allergenes-alimentaires-par-immunoessai.html

Year Published: 2025

URL for published report: https://www.inesss.qc.ca/publications/repertoire-des-publications/publication/dosage-des-igg4-specifiques-aux-allergenes-alimentaires-par-immunoessai.html

English language abstract: An English language summary is available

Publication Type: Full HTA

Country: Canada

Organisation Name: Institut national d'excellence en sante et en services sociaux

Contact Address: L'Institut national d'excellence en sante et en services sociaux (INESSS) , 2021, avenue Union, bureau 10.083, Montreal, Quebec, Canada, H3A 2S9;Tel: 1+514-873-2563, Fax: 1+514-873-1369

Contact Name: demande@inesss.qc.ca

Contact Email: demande@inesss.qc.ca

Copyright: L'Institut national d'excellence en sante et en services sociaux (INESSS)