Transcript Poster - Northern Arizona University

Risk Factors for a Bilateral 4-6 kHz Notch in US Youth: Data from the NHANES (2005-2010)
Ishan Bhatt, PhD, CCC-A, Michael Skelton, AuD, CCC-A & O’neil Guthrie, PhD, CCC-A
Communication Sciences and Disorders, Northern Arizona University
BACKGROUND
 Noise-induced hearing loss (NIHL) is a permanent hearing loss that
remains a hearing health concern despite the implementation of
national standards for hearing protection.
 NIHL is defined as a bilateral audiometric hearing loss at the
frequency range between 3000 to 6000 Hz with recovery at 8000 Hz.
NIHL slowly develops as a function of continuous or intermittent
acoustic exposure and duration (Kirchner et al, 2012).
 NIHL is a complex disorder which is caused by multiple genes in
combination with lifestyle and environmental factors. We identified
bilateral audiometric notches at 4000-6000 Hz as an NIHL phenotype
to study genetic risk factors in our previous study (Phillips et al.,
2015).
AIMES OF THE STUDY
1. To study the prevalence of unilateral notch (UN) and bilateral notch
(BN) in US youth using the National Health And Nutrition
Examination Survey (NHANES 2005-2010) database.
2. To evaluate the effect of non-genetic risk factors (i.e. gender, age,
ethnicity, family income, work-related noise exposure, recreational
acoustic exposure, acoustic exposure just prior to testing, firearm
noise exposure, tinnitus and ear canal volume) on the BN.
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 ranges from 0.2 to 1.8 cc, and
middle ear pressure ranging from -50 to 25 dapa in both ears were
considered for further analysis. (Total: 2348 participants)
Demographic and Survey data
RESULTS (continued)
 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?
 Sex of the participants was categorized as male and female.
 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 white, non-Hispanic black,
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?
RESULTS
 Prevalence of bilateral notches: 16.6 % (390 participants)
 Prevalence of unilateral notches: 39% (914 participants)
Male < Females
African American <
European American
14-15 years >
18-19 years
Unilateral
Notch
(Odds Ratio)
Associated
Variables
Bilateral Notch
(Odds Ratio)
0.753
(0.618-0.918)
0.700
(0.538-0.911)
0.753
(0.618-0.918)
Male < Females
0.585
(0.450-0.761)
African American <
European American
Noisy Job > No noisy
job
0.537
(0.376-0.767)
1.836
(1.097-3.074)
Tables: Factors associated with unilateral and bilateral audiometric notches
 Risk-factors for the audiometric notch: Multinomial logistic regression
analysis with audiometric notch as a dependent variable (with 3 levels: no
notch, unilateral notch, bilateral notches) and with above listed factors as
dependent variables were used to identify the risk-factors of the notch.
 The analysis revealed that males showed lower prevalence of notches
compared to females.
 Participants with African American ancestry and history of noisy job revealed
high odds of bilateral notches.
 Unilateral notch was associated with age range of 14-15 years, and African
American ancestry.
DISCUSSION
 Prevalence of audiometric notch in US youth (16.6%) was higher than its
prevalence in college-aged musicians (12%) (Phillips et al, 2015)
 Almost 42% of the participants showed audiometric notch without reporting a
history of a noisy job, music exposure, firearm noise exposure and acoustic
exposure before audiometry.
 Audiometric notch may overestimate NIHL especially when supra-aural
transducers are used to measure hearing thresholds (Schlauch & Carney,
2011)
Audiometric Measures
 Interacoustic model AD226 audiometer with standard TDH-39
headphones were used to measure hearing sensitivity. Testing was
conducted according to a modified Hughson Westlake procedure
using automatic testing mode.
 Standing waves in the ear canal may be a candidate mechanism leading to
higher prevalence of notches in younger children with shorter ear canals.
 Future research will compare sound pressure levels in the ear canal
produced by supra-aural headphones versus insert ear headphones to test
the hypothesis that standing waves in the ear canal can cause a notch-like
pattern in the absence of noise-induced cochlear damage.
Definition of Audiometric Notch
 A drop in hearing sensitivity at 4 to 6 kHz of at least 15 dB from the
self-referenced previous best threshold in a linear progression of
frequencies, with a recovery of at least 5 dB after the notch.
Associated
Variables
Figure 1: Audiometric Notch Configuration in the NHANES (2005-2010)
database: Mean thresholds at 1000-8000 Hz for participants with no notch (blue
line) vs. notched audiogram (red line). Error bars: 95% CI