Background: The role of allergy as risk factor for Long-COVID (LC) is unclear. We aimed to systematically review and appraise the epidemiological evidence on allergic diseases as risk factors for LC (PROSPERO: CRD42023391245). Methods: We examined literature for prospective cohort studies with a follow-up duration of 12 months for LC symptoms, published within the timeframe from January 2020 and January 2023 that recruited individuals with confirmed SARS-CoV-2 infection and information on pre-existing allergic diseases. Risk of bias and certainty of evidence were assessed (GRADE). Random effects meta-analyses were used to pool unadjusted ORs within homogeneous data subsets. Results: We identified 13 studies (participants range = 39 - 1,950), all of which were associated with high risk of bias. Four of these studies did not provide data to calculate ORs. Significant associations were observed between increased LC incidences and pre-existing asthma measured in hospital-based populations ( n = 6) and pre-existing rhinitis ( n = 3) ( OR = 1.94; 95% CI [1.08, 3.50]; OR = 1.96; 95% CI [1.61, 2.39]), respectively. However, the level of certainty regarding these exposure outcome associations was very low. Conclusion: Findings show that allergies may increase the risk of LC, although the reliability of this evidence is tenuous.

A document by Ekaterina Spiridonova. Click on the document to view its contents.

Background: The European Academy of Allergy and Clinical Immunology (EAACI) is in the process of updating the guidelines on the diagnosis and management of food allergy. The existing guidelines are based on a systematic review of the literature until 30th September 2012. Therefore, a new systematic review must be undertaken to inform the new guidelines. This systematic review aims to assess the accuracy of index tests to support the diagnosis of IgE-mediated food allergy. Methods: The databases Cochrane CENTRAL (Trials), MEDLINE (OVID) and Embase (OVID) will be searched for diagnostic test accuracy studies from 1st October 2012 to 30th June 2021. Inclusion and exclusion criteria will be used to select appropriate studies. Data from these studies will be extracted and tabulated, and then reviewed for risk of bias and applicability using the QUADAS-2 tool. All evaluation will be done in duplicate. Studies with a high risk of bias and low applicability will be excluded. Meta-analysis will be performed if there are three or more studies of the same index test and food. Results: A protocol for the systematic review and meta-analyses is presented and was registered using Prospero prior to commencing the literature search. Discussion: Oral food challenges are the reference standard for diagnosis but involve considerable risks and resources. This protocol for systematic review aims to assess the accuracy of various tests to diagnose food allergy, which can be useful in both clinical and research settings.