Prevalence of Childhood Hearing Loss in Rural Alaska.

OBJECTIVES: Childhood hearing loss has well-known lifelong consequences. Certain rural populations are at higher risk for infection-related hearing loss. For Alaska Native children, historical data on hearing loss prevalence suggest a higher burden of infection-related hearing loss, but updated prevalence data are urgently needed in this high-risk population. DESIGN: Hearing data were collected as part of two school-based cluster-randomized trials in 15 communities in rural northwest Alaska over two academic years (2017-2019). All enrolled children from preschool to 12th grade were eligible. Pure-tone thresholds were obtained using standard audiometry and conditioned play when indicated. The analysis included the first available audiometric assessment for each child (n = 1634 participants, 3 to 21 years), except for the high-frequency analysis, which was limited to year 2 when higher frequencies were collected. Multiple imputation was used to quantify the prevalence of hearing loss in younger children, where missing data were more frequent due to the need for behavioral responses. Hearing loss in either ear was evaluated using both the former World Health Organization (WHO) definition (pure-tone average [PTA] > 25 dB) and the new WHO definition (PTA ≥ 20 dB), which was published after the study. Analyses with the new definition were limited to children 7 years and older due to incomplete data obtained on younger children at lower thresholds. RESULTS: The overall prevalence of hearing loss (PTA > 25 dB; 0.5, 1, 2, 4 kHz) was 10.5% (95% confidence interval [CI], 8.9 to 12.1). Hearing loss was predominately mild (PTA >25 to 40 dB; 8.9%, 95% CI, 7.4 to 10.5). The prevalence of unilateral hearing loss was 7.7% (95% CI, 6.3 to 9.0). Conductive hearing loss (air-bone gap of ≥ 10 dB) was the most common hearing loss type (9.1%, 95% CI, 7.6 to 10.7). Stratified by age, hearing loss (PTA >25 dB) was more common in children 3 to 6 years (14.9%, 95% CI, 11.4 to 18.5) compared to children 7 years and older (8.7%, 95% CI, 7.1 to 10.4). In children 7 years and older, the new WHO definition increased the prevalence of hearing loss to 23.4% (95% CI, 21.0 to 25.8) compared to the former definition (8.7%, 95% CI, 7.1 to 10.4). Middle ear disease prevalence was 17.6% (95% CI, 15.7 to 19.4) and was higher in younger children (23.6%, 95% CI, 19.7 to 27.6) compared to older children (15.2%, 95% CI, 13.2 to 17.3). High-frequency hearing loss (4, 6, 8kHz) was present in 20.5% (95% CI, 18.4 to 22.7 [PTA >25 dB]) of all children and 22.8% (95% CI, 20.3 to 25.3 [PTA >25 dB]) and 29.7% (95% CI, 27.0 to 32.4 [PTA ≥ 20 dB]) of children 7 years and older (limited to year 2). CONCLUSIONS: This analysis represents the first prevalence study on childhood hearing loss in Alaska in over 60 years and is the largest cohort with hearing data ever collected in rural Alaska. Our results highlight that hearing loss continues to be common in rural Alaska Native children, with middle ear disease more prevalent in younger children and high-frequency hearing loss more prevalent with increasing age. Prevention efforts may benefit from managing hearing loss type by age. Lastly, continued research is needed on the impact of the new WHO definition of hearing loss on field studies.

Changing the Paradigm for School Hearing Screening Globally: Evaluation of Screening Protocols From Two Randomized Trials in Rural Alaska.

OBJECTIVES: Diagnostic accuracy was evaluated for various screening tools, including mobile health (mHealth) pure-tone screening, tympanometry, distortion product otoacoustic emissions (DPOAE), and inclusion of high frequencies to determine the most accurate screening protocol for identifying children with hearing loss in rural Alaska where the prevalence of middle ear disease is high. DESIGN: Hearing screening data were collected as part of two cluster randomized trials conducted in 15 communities in rural northwest Alaska. All children enrolled in school from preschool to 12th grade were eligible. Analysis was limited to data collected 2018 to 2019 (n = 1449), when both trials were running and measurement of high frequencies were included in the protocols. Analyses included estimates of diagnostic accuracy for each screening tool, as well as exploring performance by age and grade. Multiple imputation was used to assess diagnostic accuracy in younger children, where missing data were more prevalent due to requirements for conditioned responses. The audiometric reference standard included otoscopy, tympanometry, and high frequencies to ensure detection of infection-related and noise-induced hearing loss. RESULTS: Both the mHealth pure-tone screen and DPOAE screen performed better when tympanometry was added to the protocol (increase in sensitivity of 19.9%, 95% Confidence Interval (CI): 15.9 to 24.1 for mHealth screen, 17.9%, 95% CI: 14.0 to 21.8 for high-frequency mHealth screen, and 10.4%, 95% CI: 7.5 to 13.9 for DPOAE). The addition of 6 kHz to the mHealth pure-tone screen provided an 8.7 percentage point improvement in sensitivity (95% CI: 6.5 to 11.3). Completeness of data for both the reference standard and the mHealth screening tool differed substantially by age, due to difficulty with behavioral testing in young children. By age 7, children were able to complete behavioral testing, and data indicated that high-frequency mHealth pure-tone screen with tympanometry was the superior tool for children 7 years and older. For children 3 to 6 years of age, DPOAE plus tympanometry performed the best, both for complete data and multiply imputed data, which better approximates accuracy for children with missing data. CONCLUSIONS: This study directly evaluated pure-tone, DPOAE, and tympanometry tools as part of school hearing screening in rural Alaskan children (3 to 18+ years). Results from this study indicate that tympanometry is a key component in the hearing screening protocol, particularly in environments with higher prevalence of infection-related hearing loss. DPOAE is the preferred hearing screening tool when evaluating children younger than 7 years of age (below 2nd grade in the United States) due to the frequency of missing data with behavioral testing in this age group. For children 7 years and older, the addition of high frequencies to pure-tone screening increased the accuracy of screening, likely due to improved identification of hearing loss from noise exposure. The lack of a consistent reference standard in the literature makes comparing across studies challenging. In our study with a reference standard inclusive of otoscopy, tympanometry, and high frequencies, less than ideal sensitivities were found even for the most sensitive screening protocols, suggesting more investigation is necessary to ensure screening programs are appropriately identifying noise- and infection-related hearing loss in rural, low-resource settings.