REVIEW ARTICLE |
a Oregon Evidence-based Practice Center, Department of Medical Informatics and Clinical Epidemiology
b Department of Medicine, Oregon Health & Science University, Portland, Oregon
c Women and Children's Health Research Center, Providence Health and Services, Portland, Oregon
| ABSTRACT |
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METHODS. Medline and Cochrane databases were searched to identify articles published since the 2002 recommendation. Data from studies that met inclusion criteria were abstracted, and studies were rated for quality with predetermined criteria.
RESULTS. A good-quality retrospective study of children with hearing loss indicates that those who had early versus late confirmation and those who had undergone universal newborn screening versus none had better receptive language at 8 years of age but not better expressive language or speech. A good-quality nonrandomized trial of a large birth cohort indicates that infants identified with hearing loss through universal newborn screening have earlier referral, diagnosis, and treatment than those not screened. These findings are corroborated by multiple descriptive studies of ages of referral, diagnosis, and treatment. Usual parental reactions to an initial nonpass on a hearing screen include worry, questioning, and distress that resolve for most parents. Cochlear implants have been associated with higher risks for bacterial meningitis in young children.
CONCLUSIONS. Children with hearing loss who had universal newborn hearing screening have better language outcomes at school age than those not screened. Infants identified with hearing loss through universal screening have significantly earlier referral, diagnosis, and treatment than those identified in other ways.
Key Words: evidence-based medicine hearing impairment hearing screening newborn screening systematic reviews
Abbreviations: USPSTF—US Preventive Services Task Force UNHS—universal newborn hearing screening PCHL—permanent congenital hearing loss JCIH—Joint Committee on Infant Hearing OAE—otoacoustic emission ABR—auditory brainstem response CI—confidence interval NNS—number needed to screen
This systematic evidence review updates a previous review for the US Preventive Services Task Force (USPSTF) on universal newborn hearing screening (UNHS) to detect moderate-to-severe bilateral permanent congenital hearing loss (PCHL).1,2 Based on research available in 2001, the USPSTF concluded that the evidence was insufficient to recommend for or against routine screening of newborns for PCHL during the postpartum hospitalization.3
In their previous recommendation, the USPSTF found that evidence was inconclusive regarding whether earlier treatment resulting from UNHS leads to clinically important improvement in speech and language skills at 3 years of age and beyond, because existing studies had important design limitations. Since then, additional studies with speech and language outcomes of children screened or not screened as newborns have been published. This update focuses on these new studies.
The Joint Committee on Infant Hearing (JCIH), composed of representatives from audiology, otolaryngology, pediatrics, education, and state speech and hearing programs, provides position statements and establishes practice standards for early identification, intervention, and follow-up care for infants and young children with hearing loss. According to the JCIH, hearing screening should identify newborns at risk for specifically defined hearing loss that interferes with development.4,5 The aim for UNHS programs is detection of permanent sensory or conductive hearing loss averaging 30 to 40 dB or more in the frequency region important for speech recognition (
500–4000 Hz). The focus of UNHS is on congenital as opposed to acquired or progressive hearing loss that may not be detected in the newborn period.
The rate of PCHL among newborns ranges from 1 to 3 per 1000 live births.6–9 Compared with children with normal hearing, those with hearing loss have more difficulty learning vocabulary, grammar, word order, idiomatic expressions, and other aspects of verbal communication.10 Hearing loss in children is also associated with delayed language, learning, and speech development and with low educational attainment.4 Hearing disorders have also been associated with increased behavior problems, decreased psychosocial well-being, and poor adaptive skills.11–13
Risk factors associated with a higher incidence of PCHL include NICU admission for
2 days; syndromes associated with hearing loss; family history of hereditary childhood sensorineural hearing loss; craniofacial abnormalities; and congenital infections.4 However,
50% of infants with PCHL do not have any known risk factors.9,14–18
In the JCIH 2000 and 2007 position statements,4,5 the JCIH endorsed integrated, interdisciplinary state and national systems of UNHS; evaluation; and family centered intervention outlined in Fig 1. In addition, the JCIH recommended that all infants with risk indicators should undergo periodic monitoring for 3 years. The 2007 statement expands screening protocols for NICU infants and provides additional guidance for the diagnostic audiology evaluation, medical evaluation, early intervention, surveillance, communication, and tracking.5
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With legislation for UNHS being enacted in 39 US states in recent years, screening practices and procedures have become routine in the postpartum hospital setting. Newborn hearing screening is generally well accepted and tolerated by parents. Rates of refusals in a US community-based health system were reported as 7 of 8707 during the first 10 months of 2007 (Christi Sperry, AuD, Providence Health and Services, written communication, 2007).
Infants not passing the newborn screening tests are referred for confirmatory testing for a diagnosis of PCHL. The American Academy of Pediatrics has set a referral standard of <4% of all screened newborns, and some hospitals use this measure to monitor quality of the screening program. Confirmation requires an evaluation by an audiologist using behavioral, as well as technological, methods. Although the American Academy of Pediatrics has set a standard of 95% for compliance with follow-up testing, this rate is typically much lower depending on tracking systems and local practices and services.21–24
The JCIH recommends that early intervention services should be designed to meet the individualized needs of the infant and family, including acquisition of communication competence, social skills, emotional well-being, and positive self-esteem.4 Early intervention includes evaluation for amplification or sensory devices, surgical and medical evaluation, and communication assessment and therapy. Cochlear implants are often considered in infants with severe-to-profound hearing loss after inadequate response to hearing aids.25–28 Research in neurologic and auditory cortical development suggests that early verses late implantation may be linked to more normal cortical auditory pathway development.29–31
| METHODS |
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We conducted literature searches to systematically identify articles relevant to the key questions.33 Databases included the Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, Database of Abstracts of Reviews of Effects (through the fourth quarter of 2007), and Ovid Medline (2000 to November 2007 for key questions 1 and 2 and 1996 to November 2007 for key question 3). Additional articles were obtained from reference lists of related reviews, studies, editorials, reports, Web sites, and by consulting experts. Figure 3 describes results of the searches.
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Study quality was rated by using design-specific criteria developed by the USPSTF.32 The overall rating of each study considers internal validity and applicability. Descriptive studies without quality criteria are summarized. An outcomes table estimating the number needed to screen under various assumptions was determined using estimates from the most relevant studies.
The USPSTF advised the Oregon Evidence-based Practice Center in formulating and reporting this review. Additional experts provided comments on an earlier draft.
| RESULTS |
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A good-quality retrospective cohort study evaluated the effect of UNHS on speech and language outcomes of children with PCHL.35 A total of 120 children with PCHL were identified from a cohort of 157000 children born in 8 districts of southern England between 1992 and 1997 and underwent speech and language assessment at school age (mean: 7.9 years; range: 5.4–11.7 years). Included children were either part of the Wessex Universal Neonatal Hearing Screening Trial,16 constituting 34% of the birth cohort in this study, or from districts in greater London providing UNHS or not at the time of birth. Seventy-one percent of children with PCHL in the cohort who were eligible for the study participated. Participants were similar to nonparticipants in age, gender, and severity of hearing loss.
Protocols for screening and confirmation of hearing impairment were similar at all of the sites, and all of the children had bilateral impairment of a
40-dB hearing level.16 All of the children were also screened using the Health Visitor Distraction Test at 7 to 8 months of age as usual care in the United Kingdom. Therapy was provided for all of the children as a public health service and included education and audiology services with access to hearing aids. Sixty-three age-matched children with normal hearing underwent testing to derive z scores for outcome measures.
Baseline characteristics were similar between comparison groups. Outcome measures were adjusted for degree of hearing loss, maternal education, and age-adjusted nonverbal ability. Receptive language was evaluated by the Test for Reception of Grammar, British Picture Vocabulary Scale, and aggregate scores. Expressive language was evaluated by the Renfrew Bus Story Test sentence information and 5 longest sentences and aggregate scores. Speech was evaluated by the Children's Communication Checklist speech scale. Evaluators were blinded to the children's histories.
Children with hearing impairment confirmed by
9 months of age had significantly better age-adjusted scores than those confirmed later on 2 tests of receptive language and 1 of 2 tests of expressive language but not on the speech scale. All of the aggregate scores for receptive and expressive language were significantly better for the early confirmation group. Differences in higher scores for early versus late confirmation are equivalent to an increase of 10 to 12 points in the verbal compared with nonverbal IQ.
Children who underwent UNHS had better scores than those who did not on 2 tests of receptive language but not on 2 tests of expressive language or speech. Aggregate scores for receptive language were better for the UNHS group.
Limitations of the study include the potential for underestimation of the size of benefit because the system of screening and follow-up has improved since the study birth cohort underwent these processes. Also, it is not clear whether children not undergoing UNHS had the onset of hearing impairment after birth or not. A sensitivity analysis indicated that benefit for the UNHS group would have been higher if all of the cases in the study were truly congenital. Speech was assessed on the basis of parental or professional report, which may lack sensitivity as an outcome measure, rather than by direct measurement. This study does not report the proportions of hearing-impaired children that would have been considered high versus average risk for hearing impairment at birth. However, the proportion of children with other disabilities (13%–26%), a possible surrogate for risk at birth, was similar between early versus late confirmation and UNHS versus not-screened comparison groups.
A fair-quality retrospective cohort study conducted in Australia provides speech and language outcomes for a birth cohort exposed to targeted newborn hearing screening.36 This study examined the relationship of age at diagnosis of PCHL and severity of impairment on several language, speech, and reading measures in children 7.0 to 8.0 years of age who were fitted with hearing aids by age 4.5 years. All of the children born in the state of Victoria who were identified with PCHL through risk-based screening of infants, universally available behavioral hearing screening at 8 to 10 months of age, and other referral mechanisms were included. The government provided services for all of the eligible children and data obtained at the time that services were used in the study.
Several outcome measures were examined using validated methods, including receptive and expressive language, receptive vocabulary, cognition, articulation, reading comprehension, intelligibility, and family functioning. Evaluators were blinded to the children's history and hearing status. Regression models were constructed that controlled for confounders, including nonverbal IQ, maternal education, paternal occupational prestige, and family functioning.
Few children in the cohort were diagnosed with PCHL at <6 months of age (n = 11) or 12 months (n = 28). The mean age of diagnosis was 21.6 months, and the mean age of hearing aid fitting was 23.2 months. Comparisons of characteristics between early versus late-diagnosed children were not reported, except that the age at diagnosis was negatively correlated with severity at diagnosis. Age at diagnosis did not contribute significantly to the variance on any measures except receptive vocabulary; however, the small number of children diagnosed at young ages may provide inadequate power to evaluate an age effect. The severity of impairment contributed significantly to the variance on all of the measures except reading comprehension. Language outcomes were >25 points lower than expected from IQ scores.
Several other observational studies report the effects of early intervention programs.37–45 These studies were reviewed for the previous USPSTF recommendation. All of these studies have important methodologic limitations, including the use of convenience samples, nonblinded assessments, and lack of information on attrition and follow-up, among others.1,2 All of these studies report better outcomes for children with hearing impairment identified and/or treated early versus late.
Key Question 2: Compared With Targeted Screening, Does Universal Screening Increase the Chance That Treatment Will Be Initiated by 6 Months of Age for Infants at Average Risk or for Those at High Risk?
The Wessex Universal Neonatal Hearing Screening Trial is a good-quality nonrandomized, controlled trial investigating whether the addition of UNHS to usual care screening at 7 to 8 months of age versus usual care screening alone increases detection and improves the early management of infants with PCHL in the United Kingdom.16 The trial included all of the newborns born in 4 participating hospitals from 1993 to 1996, including 25609 born during periods of UNHS and 28172 not screened as newborns. Newborns screening positive using OAE followed by ABR for those who failed the first test were referred for audiologic assessment to determine their hearing levels. All of the infants were also subjected to screening using the Health Visitor Distraction Test at 7 to 8 months of age as usual care. Children with abnormal newborn screening tests, abnormal Health Visitor Distraction Tests, or additional concern for impairment were referred to audiology services. These are public health services available to all children.
All of the newborns enrolled in the Wessex Trial were included in an 8-year follow-up study.15 Information about diagnoses and management was obtained from multiple sources (records, therapists, etc). Children with postnatal causes of hearing impairment were excluded from the study.
In this analysis, 1 additional case of PCHL was referred before the age of 6 months for every 1969 (1011–12896) infants in the UNHS population. More infants with true PCHL were referred to audiology services before 6 months of age if they were born during periods with UNHS rather than during periods without (74% vs 31%; difference: 43% [95% confidence interval (CI): 19%–60%]; P = .001). Adjustment for the effect of severity of hearing impairment on age of referral increased the odds ratio between newborn screening and early referral from 6.3 to 6.9 (95% CI: 2.2–22.0; P = .001). The age at referral was lower for children undergoing UNHS versus not (0 vs 8 months; P < .001).
Results may have been limited by the effects of initiating a new clinical service as part of the trial. Parents of 7 children with subsequently diagnosed hearing impairment initially refused newborn screening. Also, 23% of all of the cases included in the analysis may actually have had progressive hearing losses that would not be detected at birth. Although referrals were early in the study, management was often initiated later than desired (48% after 18 months).
Several descriptive studies report follow-up data from UNHS programs (Table 1). 9,16–18,46,47 In the most recent study of a national UNHS program in the United Kingdom, referred infants who were not admitted to the NICU had their first follow-up visits at a median age of 4 weeks, were diagnosed at 10 weeks, enrolled in education services at 10 weeks, and were fitted with hearing aids at 14 weeks.17 Infants from the NICU used these services at slightly older ages and had their first follow-up at 9 weeks, were diagnosed at 13 weeks, and received hearing aids at 24 weeks.
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Key Question 3: What Are the Adverse Effects of Screening and Early Treatment?
Two fair-quality cohort studies,49,50 1 poor-quality case-control study,51 and 5 survey studies with >40% response rates52–56 provide relevant information on adverse effects of newborn hearing screening (Table 2). In a case-control study, parents expressed anxiety when their infants did not pass the initial screening test that resolved for most after a confirmatory test indicated normal results.51 Additional studies reported no differences in concern and anxiety between parents with newborns who passed or did not pass screening tests,49,50 although parents with newborns with confirmed hearing loss had higher levels of distress than those with confirmed normal hearing.51,53
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Few studies of psychological issues associated with treatment specifically focus on young children or the adverse effects of early treatment. Parents of 123 children with hearing loss (average: 38 months of age) were asked about their stress and quality of life related to 3 types of treatments.64 All had cochlear implants, hearing aids, or switched treatments (hearing aid first then cochlear implants). Parents of children with switched treatments had significantly reduced quality of life and increased stress, whereas parents of children using only cochlear implants had improved quality of life and normal stress.64
Parents of 28 children 12 to 30 months old undergoing cochlear implantation in Turkey noted on questionnaires that making the decision for cochlear implantation was stressful.65 Families were anxious about possible device failure and maintenance of the equipment and acknowledged that their children needed more support from the family after the implantation. Most parents reported benefits of implantation, including improved communication, self-confidence, well-being, and social relationships.
Yield of Screening
Although no studies directly compare the yields of universal versus targeted screening approaches, estimates can be determined by applying results of relevant studies in an outcome table model (Table 3). Assumptions for the model include the proportion of newborns considered high risk,15 the prevalence of PCHL in populations at high and average risk,1 the proportion not screened in the hospital,66 the sensitivity of 2-stage screening,15 the compliance with follow-up testing (estimated), the accuracy of diagnostic tests,1 and the proportion of newborns at average risk diagnosed with PCHL by 3 months (estimated). Assumptions in this model differ from those in the previous evidence review because they draw from recently published data of universal and targeted screening.15,66 Using these assumptions, if 10000 newborns underwent UNHS, there would be 11 to 12 diagnosed cases by 3 months of age, 86 false-positive screening test results, and possibly 1 missed case. The number needed to screen (NNS) to diagnose 1 case would be 878. If only newborns at high risk underwent screening, there would be 4 or 5 diagnosed cases, 6 false-positive screening test results, and 8 or 9 missed cases. The NNS to diagnose 1 case would be 178.
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| DISCUSSION |
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No trials directly compare targeted screening with UNHS and report data about the initiation of early treatment for infants at average risk or those at high risk. Data from a large nonrandomized trial and descriptive studies indicate that infants at average and high risk with PCHL born in hospitals with UNHS have earlier referral and initiation of treatment than those born in hospitals without UNHS. The most impressive follow-up measures come from the most recently published studies, potentially reflecting refinements in screening techniques, system and process improvements, incorporation of UNHS as a routine practice, and increasing commitment to implementing successful programs in response to practice and policy changes.
Studies of adverse effects of screening indicate that usual parental reactions to an initial nonpass include worry, questioning, and distress. Negative emotions resolve for most parents when a diagnostic test is provided with a normal result. No studies addressed the adverse effects of delaying screening of PCHL. Now that practice standards exist, it would be difficult to conduct adequate comparison studies of early versus late initiation of treatment to evaluate both benefits and adverse effects.
A major limitation of the application of the key studies in this update is that they were conducted outside of the United States. Although the methods of screening and the inpatient maternity experiences are likely similar, the processes of referral, follow-up, and treatment would be expected to differ. Currently, there is no standard method in the United States to track children through these processes to ultimately obtain language outcomes from a birth cohort, as was done in the United Kingdom study,35 although approaches to do so are being piloted. Factors influencing follow-up and treatment in the United States would need to be considered, as well as exposure to UNHS when determining long-term outcomes.
| CONCLUSIONS |
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Results of this review indicate that infants identified with PCHL through UNHS have significantly earlier referral, diagnosis, and treatment than those identified in other ways. Although the clinical community has acknowledged the significance of early treatment for many years, evidence of its effect on long-term functional outcomes has been limited. New data on improved language outcomes at school age strengthen the case for UNHS but are also dependent on effective methods of referral, follow-up, and treatment. As these needs are being addressed with ongoing projects, further research will be required to demonstrate effectiveness for the entire process that UNHS initiates.
| ACKNOWLEDGMENTS |
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We thank Dr Colin Kennedy (University of Southampton, Southampton, United Kingdom), Kristi Sperry (audiologist, Providence Health and Services in Oregon), and Andrew Hamilton (librarian, Oregon Health and Science University) for important contributions to this project.
| FOOTNOTES |
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Address correspondence to Heidi D. Nelson, MD, MPH, Oregon Evidence-based Practice Center, Oregon Health & Science University, Mail Code BICC, 3181 SW Sam Jackson Park Rd, Portland, OR 97239-3098. E-mail: nelsonh{at}ohsu.edu
The authors have indicated they have no financial relationships relevant to this article to disclose.
The findings and conclusions in this document are those of the authors, who are responsible for its content, and do not necessarily represent the views of AHRQ. No statement in this report should be construed as an official position of the AHRQ or of the US Department of Health and Human Services.
| REFERENCES |
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This article has been cited by other articles:
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US Preventive Services Task Force Universal Screening for Hearing Loss in Newborns: US Preventive Services Task Force Recommendation Statement Pediatrics, July 1, 2008; 122(1): 143 - 148. [Abstract] [Full Text] [PDF] |
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