Children with unilateral hearing loss may have lower intelligence quotient scores: A meta-analysis

Objectives/Hypothesis In this meta-analysis, we reviewed observational studies investigating differences in intelligence quotient (IQ) scores of children with unilateral hearing loss compared to children with normal hearing. Data Sources PubMed Medline, Cumulative Index to Nursing and Allied Health Literature, Embase, PsycINFO. Methods A query identified all English-language studies related to pediatric unilateral hearing loss published between January 1980 and December 2014. Titles, abstracts, and articles were reviewed to identify observational studies reporting IQ scores. Results There were 261 unique titles, with 29 articles undergoing full review. Four articles were identified, which included 173 children with unilateral hearing loss and 202 children with normal hearing. Ages ranged from 6 to 18 years. Three studies were conducted in the United States and one in Mexico. All were of high quality. All studies reported full-scale IQ results; three reported verbal IQ results; and two reported performance IQ results. Children with unilateral hearing loss scored 6.3 points lower on full-scale IQ, 95% confidence interval (CI) [-9.1, -3.5], P value < 0.001; and 3.8 points lower on performance IQ, 95% CI [-7.3, -0.2], P value 0.04. When investigating verbal IQ, we detected substantial heterogeneity among studies; exclusion of the outlying study resulted in significant difference in verbal IQ of 4 points, 95% CI [-7.5, -0.4], P value 0.028. Conclusions This meta-analysis suggests children with unilateral hearing loss have lower full-scale and performance IQ scores than children with normal hearing. There also may be disparity in verbal IQ scores.