Mild Bilateral and Unilateral Hearing Loss in Childhood: A 20-Year View of Hearing Characteristics, and Audiologic Practices Before and After Newborn Hearing Screening

Objectives: There is some evidence that the presence of even mild degrees of hearing loss and unilateral loss in early childhood can negatively affect typical development. Consequently, the identification of all children with permanent hearing loss including those with milder degrees of hearing loss is currently targeted through some newborn hearing screening initiatives. The objectives of this study were to document the proportion of children identified with mild bilateral or unilateral hearing loss (MBUHL) before and after the implementation of a universal newborn hearing screening program (UNHS). A second objective was to examine the clinical characteristics and audiologic management of this population of children. Design: This population-based study involved an analysis of data on children with hearing loss; these data had been collected prospectively over a 20-year period from 1990 to 2010 in a publicly funded pediatric teaching hospital in Canada, which provided diagnostic audiology services for all children in the region. The proportion of all children with hearing loss identified with MBUHL before and after implementation of UNHS and their clinical profiles were documented. Data related to amplification use were also retrospectively extracted from detailed medical chart reviews to investigate clinical recommendations regarding amplification and subsequent use of hearing devices. Factors affecting amplification decisions and amplification use were examined. Results: A total of 381 of 823 children (46.3%) aged 0 to 18 years who were identified with permanent nonacquired hearing loss presented with MBUHL. The proportions identified were similar in the pre- and post-UNHS periods (p = 0.207). Before UNHS children were identified at a median age of 5.0 years (interquartile range: 3.6 to 7.0) compared with a median of 0.8 years, (interquartile range: 0.3 to 2.3) post-UNHS. Progression of hearing loss was documented for 22% of all children, and for the group identified since UNHS, 32.4% experienced deterioration in hearing thresholds. Although 87.2 % of children received recommendations for amplification, more than 50% experienced considerable delay from identification to amplification. Age at identification and severity of hearing loss in the better ear were associated with amplification decisions for bilateral but not unilateral loss. Conclusions: MBUHL constitutes almost half of childhood hearing loss. UNHS has lowered age of confirmation of MBUHL by 4 to 5 years. Delay to amplification suggests uncertainty of the benefit of intervening early for these losses. Further research is required to determine the effects of early-identified MBUHL on children's development and to document the benefits of early amplification.