High incidence of hearing impairment in single neonatal unit

Dr Tammy Brinsmead¹, Ms Melanie Dowling², Ms Lynne Cruden¹

 ²John Hunter Children’s Hospital Department of Audiology, New Lambton Heights, Australia,

 ³University of Newcastle, Callaghan, Australia

Background:

Hearing impairment is a complication of extreme prematurity.  It is twice as common after birth before 25 weeks gestation(1).  In 2007-2012, 7.7% of John Hunter Children’s Hospital Neonatal Unit (JHCHNU) infants <29 weeks or <1000g required hearing aids or cochlear implants.  This was three times the state average of 2.6%.

Aims:

1. To determine if differences in referral pathways resulted in more John Hunter Children’s Hospital Network (JHCHN) patients receiving aids or implants.

2. To establish if the distribution of extremely premature infants in NSW/ACT accounted for increased hearing impairment in JHCHNU infants.

3. To assess if hearing outcomes in JHCHNU improved in 2013-15.

Methods:

1. JHCHN infants born 2007-2015 and fitted with aids or implants were stratified by audible decibels (dB) and gestational age.

2. The incidence of aids or implants in JHCHNU and all NSW/ACT infants was compared for the two time periods.

Results:

1. JHCHN referred to Australian Hearing at 20-25dB, in contrast to 30dB in the other two districts. All JHCHN infants fitted with aids or implants had thresholds ≥ 30dB.

2. 29/144 (20%) of <25 week NSW/ACT infants were admitted at JHCHNU. In 2007-2012 at JHCHNU, 4/21 (19%) of hearing impaired infants <28 weeks or <1000g were born before 25 weeks gestation.  In NSW/ACT in the same period, 10/44 (23%) of hearing impaired extremely premature or extremely low birth weight babies were <25 weeks gestation.

3. In 2013-2015 at JHCHNU, 5/201 (2.5%) babies <28 weeks or <1000g required aids or implants. None of these was less than 25 weeks gestation.

Conclusions:

The high incidence of hearing impairment in JHCHNU from 2009-2012 was not explained by referral pathways or gestational age.  Aids and implants were less common in the subsequent three years.

References:

1. Report of the Australian and New Zealand Neonatal Network 2016

Biography:

Tammy qualified as a neonatologist in 2011 and is currently a fellow at John Hunter Children’s Hospital in Newcastle.