The Joint Committee on Infant Hearing (JCIH) (2007) has recommended targeted surveillance of at-risk infants using a risk factor registry, in conjunction with parent and/or professional monitoring, to detect hearing loss that develops post newborn hearing screen. However, criticisms of these recommendations are emerging and include (1) the lack of evidence for the majority of the risk factors on the JCIH registry in detecting postnatal hearing loss, (2) the large number of children without risk factors who develop a postnatal hearing loss, (3) the lack of parental co-operation in providing risk factors and attending appointments, and (4) the difficulties in behaviourally identifying hearing loss in young children. Given these criticisms, many programs are failing to abide by the JCIH recommendations and are instead developing their own monitoring systems that are only loosely based on the JCIH (2007) guidelines. This, in turn, leads to a lack of consistency across targeted surveillance programs, particularly in regard to risk factors incorporated within programs and the frequency of audiology appointments. The current research program aimed to investigate extensively whether there was evidence-based support for targeted surveillance programs using a risk factor registry to detect postnatal hearing loss or whether other programs were available that may be more effective than targeted surveillance. To achieve this aim, the project was divided into three sections; a systematic literature review (study one), an analysis of Queensland’s Healthy Hearing targeted surveillance program (study two and three), and a comparison between the literature and the outcomes of Queensland’s program (study four). Formal recommendations for risk factor registries have been proposed as a result of this research.
The first study in the research series, the systematic literature review, investigated whether there was evidence-based support for targeted surveillance programs using a risk factor registry within the literature. Particularly, it investigated questions that arose along the targeted surveillance pathway including (1) risk factors used to determine a referral, (2) referral frequencies, (3) the relationship between risk factors and a postnatal hearing loss, and (4) other systems that may be more efficient than the use of risk factors. The systematic literature review revealed significant gaps in the literature for risk factors associated with postnatal hearing loss and the need for further research.
The second study consisted of an analysis of Queensland’s targeted surveillance program. During the study period of September 2004 to December 2009, 7,320 children (2.8% of 261,328) were referred for targeted surveillance, of which 56 were identified with a postnatal hearing loss (0.77%). The risk factors of syndrome, craniofacial anomalies, and severe asphyxia had the highest yield of positive cases of postnatal hearing loss, whereas, low birth weight (LBW), bacterial meningitis, and professional concern had a particularly low/nil yield. Limitations of the targeted surveillance program were also noted and included (1) a high lost contact rate, (2) delays in first assessment, (3) a large number of children required on-going assessments, and (4) extensive testing was completed on children with normal hearing. Although positive cases of postnatal hearing loss were detected, the limitations of the targeted surveillance program questions the usefulness of this service delivery model.
The third study used a subset of the cohort from the second study and focused primarily on the risk factors in children who had completed their appointment series according to Queensland Health protocol and were discharged from the targeted surveillance program. Particularly, this study aimed to investigate the risk factors that were most likely to predict the occurrence of postnatal hearing loss. Formal factorial analysis revealed that two risk factors (namely, family history and craniofacial anomalies), predicted the occurrence of postnatal hearing loss in children, whereas, one risk factor (LBW) did not.
The final study in the research series combined the outcomes of the previous three studies to arrive at formal recommendations for risk factor registries incorporated within targeted surveillance programs. Recommendations are as follows. Children with the risk factors of family history and craniofacial anomalies should have their hearing monitored throughout early childhood, whereas, children with LBW as a risk factor should not. Children with a syndrome or prolonged ventilation as a risk factor may potentially require monitoring; however, the evidence was not definitive. Similarly, children with the risk factors of bacterial meningitis, hyperbilirubinemia, and professional concern may not need to have their hearing monitored; however, again the evidence was not definitive. No recommendations were able to be made for the risk factors of severe asphyxia and congenital infection due to inconclusive and/or conflicting evidence.
This research program has presented the first large scale analysis of a targeted surveillance program and has contributed critical information on risk factors associated with postnatal hearing loss. However, this research has also identified many questions that remain unanswered. Further large-scale longitudinal studies are required on children both with and without risk factors to establish the most effective method to detect postnatal hearing loss in early childhood.