Highly variable population-based prevalence rates of unilateral hearing loss after the application of common case definitions.

OBJECTIVES: This study shows how population-based estimates of the prevalence of unilateral hearing loss (UHL) in children aged 6 to 19 yrs can differ considerably with various applications of commonly accepted case definitions. It also examines demographic variables and risk factors related to UHL. DESIGN: The Third National Health and Nutrition Examination Survey, conducted from 1988 to 1994, is a national population-based, cross-sectional survey. This study examined results of audiometric testing at 0.5 to 8 kHz and demographic data from in-person examination interviews. Three definitions of UHL were used: (1) 0.5, 1, and 2 kHz > or = 15 dB pure-tone average (PTA); (2) 0.5, 1, 2, and 4 kHz > or = 15 dB PTA; and (3) 0.5, 1, and 2 kHz > or = 20 dB or PTA >25 dB at two or more frequencies above 2 kHz (3, 4, 6, and 8 kHz). Case definitions 2 and 3 are not merely subsets of case definition 1. Some overlap exists between the groups, but each case definition classifies a proportion of children who fall uniquely under that case definition. Inclusion of participants based on tympanometry results (test of middle ear function) was also examined as were demographic characteristics and risk factors associated with UHL. RESULTS: Overall, the weighted proportion of children with UHL using case definition 1 was 6.3% (approximately 3,213,000 children nationally); using case definition 2, it was 5.8% (approximately 2,958,000 nationally); using case definition 3, it was 3.0% (approximately 1,530,000 nationally). For all three case definitions, children who failed tympanometry were at higher risk for UHL than children who passed. For case definition 2, children from rural areas were at higher risk for UHL than were children from urban areas. CONCLUSIONS: This study demonstrates that different applications of well-accepted case definitions of UHL can influence population-based prevalence estimates, in this study by as much as a factor of 2. These findings highlight the importance of controlling for tympanometry status as a risk factor in such estimates. Which demographic characteristics and risk factors are significantly associated with hearing loss seem to vary depending on the case definition. These findings have implications for the interpretation of prevalence rates and risk factors in the literature on hearing loss in general. Prevalence rate estimates require careful consideration of the case definition of hearing loss, tympanometry status, and demographic characteristics.

Early intervention for children with unilateral and mild bilateral degrees of hearing loss.

Some children with unilateral hearing loss or mild bilateral hearing loss are at risk for developmental delays, educational difficulties, and other adverse effects. However, these children face several challenges in receiving services that can prevent such problems. Many do not meet existing eligibility requirements for early intervention services in their state. Information disseminated to professionals and parents often does not convey the significance of unilateral and mild bilateral hearing loss. Some professionals indicate that there are insufficient guidelines defining appropriate intervention services for these children. Factors that influence developmental outcomes in this population are not well understood, making it difficult to determine which children can benefit from intervention services. Additional data are needed about how to minimize or prevent adverse outcomes in these children. This article presents suggestions for intervention and future research that were developed by participants of the 2005 National Workshop on Mild and Unilateral Hearing Loss.

Hearing screening and diagnostic evaluation of children with unilateral and mild bilateral hearing loss.

More than 90% of newborns in the United States are now being screened for hearing loss. A large fraction of cases of unilateral hearing loss and mild bilateral hearing loss are not currently identified through newborn hearing screening. This is of concern because a preponderance of research has demonstrated that unilateral hearing loss and mild bilateral hearing loss can lead to developmental delays and educational problems for some children. To help address this probable underidentification of unilateral hearing loss and mild bilateral hearing loss among infants and children, the Centers for Disease Control and Prevention Early Hearing Detection and Intervention program and the Marion Downs Hearing Center convened a workshop in Breckenridge, Colorado, in July 2005. During this workshop, several issues related to screening and diagnosing unilateral hearing loss and mild bilateral hearing loss were identified, as well as recommendations for future research in this area. Issues identified included the lack of standardized definitions for permanent unilateral hearing loss and mild bilateral hearing loss; the use of screening protocols that are primarily designed to identify bilateral and unilateral hearing losses of a moderate degree or greater (eg, above 40 dB); calibration of screening equipment; availability of facilities that can provide the full range of audiologic, diagnostic, and management services to this pediatric population; and an overall lack of awareness by many professionals and families about the potential effect of unilateral hearing loss and mild bilateral hearing loss. Suggestions for future research, such as identifying ways to improve the identification of cases of unilateral hearing loss and mild bilateral hearing loss, were also discussed.

Hearing screening for newborns: the midwife's role in Early Hearing Detection and Intervention.

Universal newborn hearing screening is becoming the standard of care in the United States. However, there has been some controversy around this pediatric preventive health care practice. In 2001, the US Preventative Services Task Force (USPSTF), the leading independent panel of experts on prevention and primary care in the United States, reviewed the scientific literature and found inconclusive evidence to recommend for or against universal newborn hearing screening. As a result of this lack of recommendation, some pediatric providers were not screening the hearing of all newborn infants. The USPSTF released an update in July 2008 concluding there is scientific evidence to recommend newborn hearing screening for all infants. Universal newborn hearing screening is the first step in the national Early Hearing Detection and Intervention (EHDI) program. EHDI includes not only universal newborn hearing screening but also diagnostic evaluation for any infant failing the initial hearing screen and intervention services for any infant diagnosed with hearing loss. During the prenatal and postnatal periods, obstetric care providers can play a vital role in the EHDI process through education, screening, referral, and assistance with follow-up. Through these services, clinicians can work with parents and pediatric care providers to help newborns and infants develop communication and language skills that will last a lifetime.