Allergic Rhinitis in Preschoolers: A Systematic Review of Diagnostics.

Background: Most studies that seek to analyze the prevalence of allergic rhinitis do not include preschool children and the diagnosis in this age group is difficult.

Objective: Identify complementary tests to the diagnosis of allergic rhinitis in preschool children and verify if there is scientific robustness to propose a diagnostic algorithm for this condition in this age group.

Methods: Systematic review of the literature in four databases: SCIELO, PubMed/MEDLINE, LILACS and SCOPUS. Each article was initially chosen by title, abstract and by the keywords "allergic rhinitis," "diagnosis" and "preschool." Those articles selected entered the complete reading and data extraction phase. The study was registered in the International Prospective Register of Systematic Reviews under number CRD42020207053.

Results: Fourteen articles were suitable for analysis. In the assessment using Quality Assessment of Diagnostic Accuracy Studies - 2, all studies had at least one domain considered "high risk" or "undetermined risk." Seven reports of nasal cytology, seven of specific IgE, four of immediate hypersensitivity skin test, one of nasal nitric oxide, three of total IgE and one of urinary leukotriene E4 were found. Eight articles evaluated more than one diagnostic test.

Conclusion: There are no defined criteria for the diagnosis of allergic rhinitis in preschool children. Nasal cytology, serum specific IgE and immediate hypersensitivity skin test were the most used tests. A reliable diagnostic criterion in this age group is necessary so that in the future it is possible to propose a diagnostic algorithm for allergic rhinitis in preschool children.