Communication Sciences and Disorders, Northern Arizona University Risk Factors for a High-Frequency Hearing Loss in US Youth: Data from the NHANES (2005-2010) Ishan Bhatt, PhD, CCC-A , O’neil Guthrie, PhD, CCC-A, Michael Skelton, AuD, CCC-A Communication Sciences and Disorders, Northern Arizona University BACKGROUND Presbycusis is a complex disorder which is caused by multiple genes in combination with lifestyle and environmental factors. Genetic risk profiling is a promising strategy to prevent presbycusis (Ciobra et al, 2015). A recent study in college-aged musicians identified high-frequency hearing loss (HFHL) as an audiometric configuration (Phillips et al., 2015) which may be treated as a presbycusis phenotype. Tinnitus was considered present if a participant answered positive to: In the past twelve months, have you been bothered by ringing, roaring, or buzzing in your ears or head that lasts for five minutes or more? Socioeconomic status: low (PIR≤1.3), mid (PIR: 1.4-3.5) and high (PIR > 3.5). Age of participants was categorized in four subgroups: 12-13 years, 14-15 years, 16-17 years, and 18-19 years. Race/ethnicity was re-coded into non-Hispanic European American, non-Hispanic African American, Hispanic and other races (including multiracial). Firearms noise exposure was considered positive if a participant answered positively to the question: Have you ever used firearms for target shooting, hunting, or for any other purposes? Work-related noise exposure was defined as positive if a participant answered positively to the question: Have you ever had a job where you were exposed to loud noise for five or more hours a week? Music exposure was defined as positive if a participant identified exposure to loud noise or music for five or more hours per week outside of a job. History of smoking was considered positive if a participant answered positively to any of the following questions: Have you ever tried smoking? or Does anyone smoke at home? Average ear canal volume (ECV) was calculated from the tympanometric data. The quartile ranges were considered as low, moderate, moderately-high and high ECV respectively. RESULTS (continued) Figure 1: HFHL Configuration in the NHANES (2005-2010) database: Mean thresholds at 1000-8000 Hz for participants with no HFHL (blue line) vs. HFHL (red line). Error bars: 95% CI Risk-factors for the HFHL: Multinomial logistic regression analysis with a HFHL as a dependent variable (with 3 levels: no HFHL, unilateral HFHL, bilateral HFHL) and with the above listed factors as dependent variables were used to identify the risk-factors of the HFHL. The analysis revealed that unilateral HFHL was associated with race and ECV, where participants with European American ancestry and low/moderate ECV showed significantly high odds of unilateral HFHL. Bilateral HFHL was associated with race, music exposure and ECV, where participants with European American ancestry, positive history of music exposure and low/moderately-high ECV showed significantly high odds of bilateral HFHL. AIMES OF THE STUDY To study the prevalence of HFHL in US youth (12-19 years) using the National Health And Nutrition Examination Survey (NHANES 2005-2010) database. To evaluate the effect of non-genetic risk factors (i.e. gender, age, ethnicity, family income, work-related noise exposure, recreational noise exposure, acoustic exposure just before testing, firearm noise exposure, tinnitus and ear canal volume) on the bilateral HFHL. METHODS Audiometric testing was performed by NHANES (2005-10). Data was collected through household interviews followed by a standardized physical examination. Demographic and audiometric databases from NHANES 2005-06, 07-08 and 09-10 were merged. Individuals ranging in age from 12-19 years with bilateral normal otoscopic findings, compliance value ranging from 0.2 to 1.8 cc, and middle ear pressure ranging from -100 to 50 dapa in both ears were considered for the further analysis. (Total: 3595 participants) Audiometric Measures Interacoustic model AD226 audiometer with standard TDH-39 headphones were used to measure hearing sensitivity. Testing was conducted using modified Hughson Westlake procedure. Definition of High-Frequency Hearing Loss (HFHL) Configuration A drop in hearing sensitivity at 8 kHz of at least 15 dB from the self-referenced previous best threshold in a linear progression of frequencies, and minimally a 15 dB HL threshold was considered a High-Frequency Hearing Loss configuration (Phillips et al., 2015) Demographic and Survey data Sex of the participants was categorized as male and female RESULTS Prevalence of bilateral HFHL: 4.3 % (143 participants) Prevalence of unilateral notches: 19.1% (639 participants) Tables: Results of the Multinomial Logistic Regression Analysis: Factors associated with unilateral and bilateral HFHL. DISCUSSION Major finding of this study is that ECV can predict a HFHL configuration. It can be hypothesized that HFHL is related with variation in sound pressure level in the ear canal. Standing waves may be a candidate mechanism underlying a HFHL configuration. Another explanation may be derived from Gerhardt et al (1987). The authors showed that college-aged individuals with low ECV acquired highest temporary threshold shift (TTS) at higher frequencies (around 6000 Hz) compared to individuals with high ECV who acquired highest TTS at lower frequencies following an identical white noise exposure. Young adults aged 12-19 years may show lower ECV and higher resonance frequency of the ear canal than college-aged adults. Subsequently, they may acquire HFHL secondary to loud music exposure. Future research will test these hypotheses. Associated Variables Unilateral HFHL (Odds Ratio) African American < European American 0.758 (p < 0.05) Hispanic < European American 0.723 (p < 0.01) Low ECV > High ECV 1.659 (p < 0.001) Moderate ECV > High ECV 1.443 Associated Variables Bilateral HFHL (Odds Ratio) Hispanic < European American 0.588 (p < 0.05) Music Exposure > No Music Exposure 1.532 Low ECV > High ECV 1.901 Moderately-high ECV > High ECV 2.391 (p < 0.01)