Infant screening tests for hearing problems may not catch all cases of hearing loss, especially if hearing problems crop up later in infancy or childhood, according to a new study.

Almost one-third of children with hearing aids passed screening for hearing loss when they were newborns, only to be diagnosed later in infancy or early childhood, the study said.

Universal newborn hearing-screening programs were devised to identify hearing-impaired children early in their lives, so that interventions could be made before the child went deaf. The screening tests are required in 36 states, and health insurance is required to cover screening costs in 16 states, according to the National Conference of State Legislatures.

But the new study shows that children who later developed hearing loss passed screening tests as infants. The finding shows that the current screening tests are unable to catch hearing loss that may occur later in childhood, the researchers said.

Later onset of hearing loss limits doctors' ability to diagnose deafness early, researchers said. "This problem will not be solved by the current design of universal hearing screening programs," researchers wrote in the study.

In Illinois, universal hearing screening of newborns was mandated by law in 2003 in all birthing hospitals. Dr. Nancy Melinda Young, of Children's Memorial Hospital, Chicago, and her colleagues examined data for 391 children who received cochlear implants in Illinois from 1991 through 2008. The children were divided into two groups: those born before mandatory screening (264 children) and those born after (127 children).

Eight-five percent of children born after the law was implemented were screened at birth , compared with 32.6 percent of children who were screened at birth before the law passed, according to the study.

Of the 127 children born after the screening mandate, 65.4 percent of them had a known cause of or at least one risk factor for hearing loss, the study said. But 25.3 percent of those children passed hearing screenings despite their risk factors.

Children with hearing loss who passed the screening test also had a higher age of diagnosis than children whose hearing loss was detected by the screening. The average age of diagnosis of hearing loss for a child who passed the screening was 18.5 months, compared with 5.9 months for a child who failed the screening, the study said.

"This finding highlights the difficulty of identifying hearing loss in young children and underscores the reason for development of universal screening programs using objective test measures," researchers wrote.

The study was published in the March issue of the journal Archives of Otolaryngology-Head & Neck Surgery. Young serves on the medical boards of Cochlear Americas and Advanced Bionics Corp., which produces cochlear implant systems.

Pass it on: Hearing screening for newborns don't catch all cases of hearing loss, especially hearing loss that occurs later in childhood.

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