TABLE 1.

Characterization of evidence included in this narrative review.

Evidence category	Types of studies	Evidence level*	Strengths	Limitations
Mechanistic studies	In vitro cochlear models, animal studies, and molecular biology investigations	Preclinical	Provides a detailed understanding of cellular pathways and temporal progression	Limited direct translation to clinical settings; species differences
Genetic studies	Mitochondrial DNA analyses, genome-wide association studies, and pharmacogenetic investigations	Preclinical/Observational clinical	Identifies specific risk factors; allows targeted screening	Variable penetrance; incomplete understanding of gene–environment interactions
Clinical observational studies	Cohort studies, case-control studies, retrospective analyses	Observational clinical	Documents real-world incidence, risk factors, and outcomes in pediatric populations	Confounding variables; heterogeneity in definitions and outcome measures
Interventional research	Clinical trials of protective agents, monitoring protocols, and dosing strategies	Randomized clinical/Observational clinical	Provides direct evidence for preventive approaches	Limited randomized controlled trials in pediatric populations due to ethical constraints; ototoxicity endpoints are inconsistently measured across studies
Guidelines and expert opinion	Consensus statements, professional society guidelines	Guideline consensus	Synthesizes evidence into practical recommendations	May lag behind the most recent evidence; varies by region

^*Evidence Level categories: Preclinical = in vitro and/or animal model data; Observational clinical = cohort, case-control, or retrospective human studies; Randomized clinical = randomized controlled trials; Guideline consensus = professional society consensus statements or guidelines. Where a category spans multiple evidence levels, both are listed.