Early Identification Flashcards
Why is HL an “important health problem” that warrants screening?
–Unrecognized HL in young children compromises the development of speech and language
–Could consider impaired hearing as a primary health condition–cochlea is a primary sense
organ
-HL is a causal or mediator variable that along with other factors can have strong influence on long-term loang outcomes
-WHO-ICF: impairment–> activity limitation
-Family may be unaware of HL
Prevalence of congenital HL in developed countries and high-risk populations
1-3 per 1000 (.2-.3%)= prevalence
1-2% (10X greater than the genernal newborn population)= “High risk”
OAE & ABR as screening tests
- Some variation in OAE detectability and pure-tone audibility
- Strong relationship between detectability of ABR and audibility of transient sound
(e. g., clicks, tone pips, chirps)—> can est. thresholds
OAE & ABR as screening limitaions
- They do not have intrinsic validity
- errors due to environmental noise, physiological noise, natural biological variations in response to amplitude
1-3-6 benchmarks
1 month= screen
3 months=diagnosis
6 months=intervention
Sensitivity of NHS
(false negative– correct diagnosis of impaired)Little is known about sensitivity of Automated OAE (AOAE) and ABR
(AABR) systems due to problems with reliability and availability of
prevalence estimates
not always generalizable
Norton et al. 2000—- preosepctive study re: sensitivity=== insufficient sample size
Norton et al. 2000
found that at a specificity of 0.95, the sensitivities of DPOAE,
TEOAE, and ABR were in the range of about 0.6-0.65.
○ This value would be considered unacceptable for most screening programs
○ Doubts that this estimate applies to field performance of modern screening devices
■ Yields of some screening programs are consistent with well-characterized local
prevalence data
■ Severity criterion used by Norton et al. was 30 dB HL by VRA–may vary by
locations. E.g., England data used 40 dB HL in the better ear as criterion
–unacceptable
Specificity re: OAE and ABR
(can cause false positives– correct rejection ) – more info available because population prevalence of HL is low
Overall proportion of babies who fail (refer rate) is generally an accurate
estimate of the screen false positive rate given a substantial sample size that is
relatively easy to obtain.
Protocols and Equipment
● Most manufacturers target HL of 40 dB or greater
○ However, there is equipment that allows adjustments to be made to the ABR screening level as well as parameters
for OAE that can improve detection of milder HL
■ Must consider trade-off in the increased failure rate
● Automated ABR and OAEs are the primary test methods used in NBHS programs
● Norton et al., 2000 found that TEOAEs, DPOAEs, and ABR had similar abilities to identify hearing losses of 30 dB or
greater as assessed by subsequent VRA at 8-12 months corrected age
● OAEs may be preferred for hospitals with dedicated personnel who can become proficient at probe placement
○ Probe seal not necessary for ABR–often has disposable earphones/cups/muffs
● Costs can make ABR prohibitive
Follow up procedures
● 1 (screen)-3 (diagnose)-6 (intervention) benchmarks for timeliness!
● Knowledge of the method used to screen is important so that the outpatient
rescreen is the same
○ E.g., if the patient failed an ABR screen but passed an OAE screen, neural HL
could be missed
● Must have a mechanism in place for communicating with parents and primary
care providers as well as prompt referral to the EI program
● Familiarization of funding sources for amplification
● Employ evidence-based practice
Yoshinago et al. 1998
○ Provided evidence that children whose HL was identified early and received early
intervention before 6 months of age had better language outcome
Case definition in hearing screening programs
a. Most current programs target permanent HL of 30-40 dB or greater
