Electrophysiological findings of brainstem auditory evoked potentials in infants with down syndrome: A systematic review and meta-analysis

Objective: to summarize the evidence on the electrophysiological findings in the auditory brainstem response (ABR) in infants with DS.

Material and methods: This is a systematic review study, whose protocol was registered in the International Prospective Register of Systematic Reviews (PROSPERO CRD42023424139) and conducted in accordance with the recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Observational studies were included: cross-sectional and cohort studies that performed ABR evaluation in infants with DS up to two years of age, which had their results compared with normal infants, of the same age group. The search for studies was performed in the following databases: PubMed, LILACS, Scopus, CINHAL, Web of Science, Scielo, Embase and LIVIVO, and in the gray literature: Google Scholar and Proquest. There were no restrictions on language or publication date. The methodological quality of the included studies was assessed using the JBI (Joanna Briggs Institute) checklist. Phases 1 (reading of titles and abstracts) and 2 (reading in full), data extraction, assessment of methodological quality and certainty of evidence were performed independently by the reviewers. Existing disagreements were resolved in a consensus meeting.

Results: A total of 494 articles were obtained, which after removal of duplicates and independent analysis by the reviewers, ten studies were selected for qualitative synthesis and four studies were selected for meta-analysis. There was heterogeneity between the effects observed in the ABR parameters (I2 = 78 %) with an overall pooled effect size of -0.05 (95 % confidence interval of -0.13-0.03; p = 0.22) indicating no significant difference in ABR responses between groups. The certainty of the evidence assessed by GRADE was considered very low due to inconsistency and imprecision.

Conclusion: The results of the meta-analysis indicate that there are no significant diferences in ABR parameters, including waves I, III, and V and the I - V interpeak interval, between infants with and without DS up to two years of age. However, the limitations found, such as methodological heterogeneity, small sample sizes and variability in the age range of the participants, generated uncertainty in the results. Therefore, the certainty of the evidence was classified as very low, according to the GRADE methodology.