KidsAudiologist

Newborn hearing screening – is it accurate?

Posted on: March 30, 2012

At a recent NDCS Family Weekend for families of newly diagnosed children I was reminded of a question I’m asked alot – is the newborn hearing screen accurate? And the parents most likely to ask are those whose child passed newborn hearing screening but was later diagnosed with a hearing loss. So is it? Or have these children been misdiagnosed?

I believe that there is an issue here but that it might not be what is immediately thought!

The goal of newborn hearing screening is to enable the identification of as many newborns as possible who do have a hearing loss (high sensitivity) but also exclude as many newborns as possible who do not have a hearing loss (high specificity). Depending on the type of screen carried out, around 15% of babies who are tested using otoacoustic emissions (OAE), and 3% of babies tested using automated auditory brainstem response (AABR) will be referred for further testing. Between one to two babies in every 1000 are born with some level of hearing loss in one or both ears, so we know that it is much more likely that a baby is referred from screening and found to have normal hearing than the other way round. But there is a real issue with information sharing between professionals, as well as between professionals and parents…

Only half the children with permanent childhood hearing loss are born deaf. The other half develop deafness during the first few months/years. There are therefore young children who passed newborn screening and diagnosed as deaf early in life that can look like an inaccurate or late diagnosis but may have actually developed the deafness post-screening. There are some common causes of childhood deafness that cause this, such as CMV infection and genetics, that are commonly believed to be congenital (from birth) but are actually progressive early in life. One of the reasons we test for unilateral (one-sided) hearing loss in newborns in this country is because we know that a proportion go on to develop bilateral hearing loss soon after so it’s important to monitor these babies and young children. Another issue is that the screen is designed to pick up moderate or greater deafness but this isn’t explicitly laid out to parents and therefore again parents feel misled if later their child is diagnosed with mild deafness (or maybe was born with mild deafness that progressed early). Some of this we have only begun to understand better in the last few years and since universal screening was implemented – in the past children were always diagnosed later and therefore assumed to have been deaf from birth.

Although the information leaflet that is provided with newborn screening clearly says that deafness can happen at any age, most people’s perception is that a passed screen = normal hearing. Parents continue to express concerns that they have problems accessing an audiology assessment for their child. A GP may fail to refer concerned parents because everything must be OK as ‘they passed their newborn test’ and Health Visitors who used to test babies at 8 months may now assume that there’s no need to be concerned because of the early screen.

Having said all this, there is of course always the chance of error or mis-diagnosis within the system, or a false report of passing the screen. In which case any concerns of the parents should be treated seriously and investigated fully. For other families it can be helpful to discuss the ‘aetiology’ or cause of their child’s deafness and that may help to understand how and why the hearing loss happened/progressed. NDCS publishes a great booklet that is free to download called Understanding your child’s hearing tests that includes a section ‘Medical tests used to help diagnose the cause of
permanent deafness’ with more information.

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