BACKGROUND: New technology has made universal newborn hearing screening possible. Our goal was to investigate the feasibility of universal newborn screening using distortion product otoacoustic emissions (DPOAE) on infants in a community hospital in a normal newborn nursery.
METHODS: We used DPOAE to screen newborn infants from February 1997 to March 1999.
RESULTS: Of 1002 infants, 111 failed the initial screen (11.1%). When screening was repeated, only 2 infants failed. One infant failed the second screen and a tympanogram. He was treated and he passed a third use of DPOAE. An additional infant failed the repeat screen but passed the tympanogram. That infant was referred on for auditory brain response testing.
CONCLUSIONS: DPOAE testing can be accomplished easily in a normal newborn nursery with an acceptable false-positive rate when a two-stage approach is used. The cost for each test was $19.88. The cost to find the 1 infant with sensory neural hearing loss was $22,114.
In 1993 a consensus statement from the National Institutes of Health (NIH)1 recommended universal newborn hearing screening by the age of 3 months and also stated that otoacoustic emission might be the technology used for screening. These recommendations were based on the following: (1) the incidence of hearing loss is 1 to 6 per 1000; (2) only one half of the infants with hearing loss are discovered with high-risk screening; (3) the current average age at diagnosis of hearing loss is 2.5 years; and (4) early identification and treatment by the age of 6 months will improve outcomes.1 The 1994 position statement from the Joint Committee on Infant Hearing2 reiterated this recommendation.
Bess and Paradise3 and Paradise4 succinctly enumerated the difficulties with universal screening, including high false-positive rates, overall expense, patient acceptance, and feasibility. Since 1993, research and publications5-9 have supported universal screening; now the cost of identifying an infant with hearing loss is less than the cost of identifying an infant with phenylketonuria.10 Also, studies by Appuzzo and Yoshinaga-Itano11 and Yoshinaga-Itano and colleagues12 showed early identification and intervention improves language and social development, and today 37 states have more than 1 hospital providing universal hearing screening programs.13 A variety of screening devices are used, including automated auditory brainstem responses (AABR), transient evoked otoacoustic emission, and distortion product otoacoustic emissions (DPOAE).
Methods
Study Group
Well infants hospitalized from 24 to 72 hours were screened at ages 6 to 72 hours. Data was obtained from a sample of 1002 infants screened at Rapid City Regional Hospital between February 1997 and March 1999. During that period, newborn infants receiving care from family physicians and a pediatrician in the regular nursery were screened. Specific statistics on the age of each infant at screening were not kept.
The screening team consisted of a family practice physician, a registered nurse, and 2 family practice residents. All members of the team performed hearing screening.
We explained the hearing screen procedure, methods, risks, and benefits to the parents of the patient, and obtained informed consent. The follow-up plan for failed hearing screens was also outlined.
Equipment
The GSI 60 computer-based DPOAE instrument (Grason-Stadler, Inc, Milford, NH) was used to perform screenings. It generates paired frequencies F1 (65 dB) and F2 (55 dB). These frequencies travel through the middle ear to the cochlea, where a third tone is generated at the outer hair cell level. Normal cochlear stimulation in this manner produces a DPOAE at a specific frequency predicted by the formula 2F1-F2. During distortion product measurement, the frequency range of 2000 to 4000 Hz was selected for distortion product frequencies.
Procedure
The initial DPOAE measure was obtained on the morning of hospital discharge, with most infants tested between the ages of 12 and 72 hours. Average actual DPOAE screen time was 20 minutes. Passing the test was defined as an emission signal reproducible at 3 frequencies on 2 separate tests. The distortion product was required to be 5 decibels above the noise floor to be considered a pass.
Infants who failed the DPOAE measure were rescreened using DPOAE at 8 weeks. All second-stage screen failures were screened with tympanometry and DPOAE and were referred to their private physician or an ear, nose, and throat specialist. Infants that failed DPOAE and passed tympanometry were to be referred for diagnostic auditory brain response testing (Figure).
Results
Of the 1002 infants screened, 11.1% (111) failed the initial screening (Table 1). Seventy-nine infants were returned to our clinic for retesting 1 to 3 months after their initial evaluation. Two infants (0.2% of the total) failed the second screening. One infant failed the second screen and the tympanogram. He was treated and he passed the third DPOAE. An additional infant failed the repeat screen but passed the tympanogram. She was referred for auditory brain response testing and was found to have mild sensory neural hearing loss. A total of 32 infants were lost to follow-up despite frequent attempts to contact parents by telephone and mail.