Hearing screen for newborns
The NHS newborn hearing screening programme, introduced in 2002, improves the early detection of hearing impairment in babies, allowing earlier and more effective treatment for the 900 babies born each year in the UK with permanent hearing loss.
Professor David Kemp, a physicist then at London’s Royal National Throat Nose and Ear Hospital developed the idea for the screen in the late 1970s1. His work on hearing led him to identify noises – ‘otoacoustic emissions’ – that the healthy ear itself makes in response to sounds. Kemp found that he could pick these up with a microphone and analyse them with a computerised screening system in just a few minutes.
Kemp suggested that his discovery could be used as a hearing test, by placing a small soft tipped ear-piece in the outer part of the ear. He asked the British Technology Group (BTG), technology transfer company, to patent the idea. BTG had little luck attracting commercial interest, but in 1985 the MRC awarded Kemp a grant to develop the test as a practical instrument. Kemp eventually bought back the patent to develop it further, founding his own company called Otodynamics in 1988. The company’s products were used in newborn screening evaluations in the US and Otodynamics went on to win UK Queen’s Awards to Industry in 1993 and 1998.
Meanwhile, Professor Adrian Davis and colleagues at the MRC Institute of Hearing Research in Nottingham were trying to develop a hearing test that used behavioural responses, such as heart rate and respiration2. Davis also led the National Study of Hearing, which was an investigation of deafness in adults, showing that 16 per cent of adults have significant hearing impairment in both ears3. After Kemp’s advance, Davis’s group began to work on the otoacoustic idea, demonstrating its potential for highly sensitive screening4.
In 1993, the US National Institutes of Heath held a Consensus Conference, which called for the introduction of a national newborn hearing screen and recommended the otoacoustic test5. Two years later, the MRC funded a scientific visit to the US; the researchers returned and advised that the test be introduced in the UK.
Trials and reviews
Professor Davis carried out a multicentre trial in eight hospitals, which began in 1988 and was published in 19976. He targeted screening at newborn babies who were at risk from hearing impairment – a total of 7,500 babies had been tested by the end of 1995. The group concluded that targeted neonatal hearing screening programmes can identify hearing impairment in approximately 80 per cent of babies screened.
The Wellcome Trust funded a study, called the Wessex Hearing Assessment Project, of a universal newborn hearing screen, which tested all newborn babies as opposed to a few targeted ones. The results of this indicated that more cases of significant hearing impairment could be identified and treated early, compared with when the test was not used7. Commissioned by the UK Department of Health, Professor Davis reviewed neonatal screening, taking into account the results of all the UK and US studies. He concluded that, as well as being a specific and sensitive test, it was cost-effective8.
Introducing the screen
In 2000, there was a pilot study of the otoacoustic test, which compared a universal test to target screening of babies in intensive care. Following this, an evaluation of the initial implementation of the programme9 and a long campaign from the National Deaf Children’s Society and the Royal National Institute for Deaf People, the universal test was implemented in England in March 2006; each hospital now offers the screen. Over 1,600 babies are screened every day. The screen is also available in Wales, Northern Ireland and Scotland.
The screens that were previously used involved different, less effective, technology; the screen at nine months is now obsolete and the five-year screen is currently under review. “This [neonatal] technology has transformed the whole screening process,” says Professor Mark Haggard of the MRC Cognition and Brain Sciences Unit in Cambridge, former director of the MRC Institute of Hearing Research.
Thanks to the Newborn Hearing Screening Programme, the average age when children are identified as being deaf has been reduced from 20 months to three months. This is important because if a child’s deafness is undetected, he or she will not develop communication and language skills at a critical stage in her or his development.
1.Kemp (1978). Stimulated acoustic emissions from within the human auditory system. J Acoust Soc Am, 64, 1386
2. Wharrad & Davis (1997). Behavioural and autonomic responses to sound in pre-term and full-term babies. British Journal of Audiology, 31, 315
3. Davis (1995). Hearing in Adults. London, Whurr, 1010
4. Wood et al. (1998). Anomalous screening outcomes from click-evoked otoacoustic emissions and auditory brainstem response tests. British Journal of Audiology, 32, 399.
5. Early identification of hearing loss in infants and young children (1993). NIH Consensus Statement, Volume 11, Number 1
6. Lutman et al. (1997). Field Sensitivity of targeted neonatal hearing screening by transient-evoked otoacoustic emission. Ear & Hearing, 18, 265
7. Wessex Universal Neonatal Hearing Screening Trial Group (1998). Controlled trial of universal neonatal screening for early identification of permanent childhood hearing impairment. Lancet, 352, 1957
8. Davis et al. (1997). A critical review of the role of neonatal hearing screening in the detection of congenital hearing impairment, Health Technology Assessment, 1.
9. Bamford et al. (2005). Screening for hearing loss in childhood: issues, evidence and current approaches in the UK. J Med Screen, 12, 119