Factors influencing the efficacy of universal newborn hearing screening.

The debate surrounding the issue of universal hearing screening is being carried out on several levels. Although little disagreement exists over the educational, vocational, and quality-of-life benefits that would result from early identification and timely intervention of congenital hearing loss, the pragmatic issues, such as the effectiveness and the cost benefits associated with universal screening, cannot be ignored. This means that sensitivity, specificity, prevalence, and predictive value remain important factors. Determining the number of infants born with hearing loss in the United States each year, the prevalence issue is key to calculating the predictive value of newborn hearing screening. Emerging from current studies is that estimates of prevalence in the universal newborn population vary from 0.9 in 1000 for permanent bilateral hearing loss of more than 35 dB, to 3.24 in 1000 for bilateral hearing loss, to 5.95 in 1000 when unilateral and moderate hearing loss infants are counted. By comparison, the incidence of hearing loss in the NICU or at-risk population is accepted as high, somewhere between 2% and 4% or 20 to 40 in 1000. Incidence in the NICU varies depending on admission policies and level of care. In general, however, by screening the NICU and targeted at-risk populations, estimated to make up 10% to 16% of the newborn population, half or more of all newborns with severe to profound educationally disabling hearing loss are identified. Data from several well-conducted clinical studies, dating back to the first studies on the use of ABR to screen in the NICU, provide ample justification for the recommendation that all infants admitted to an NICU for longer than 24 hours should be screened for hearing impairment regardless of whether they have any of the at-risk indicators for hearing loss. In the author's opinion, screening in the NICU should be modeled on the operator-controlled ABR protocol outlined by Galambos and colleagues, with the addition that every ABR fail be screened by OAE before discharge. Unlike the targeted NICU population, the question remains for well infants, is sufficient clinical data or evidence available to justify screening all well newborns, specifically those with none of the at-risk for hearing loss indicators cared for in the well-infant nursery and who are discharged home within 24 or 48 hours? With the steady increase in the number of hospital-based universal newborn hearing screening programs implemented since the NIH Consensus Statement, additional data should become available to help resolve several outstanding issues, including prevalence and the predictive value of the various test protocols currently in use or proposed.