The aim of this project is to analyze population-based datasets and/or data from controlled studies, for prevalence and risk factors in relation to impaired hearing of children. A principal dataset for these analyses in school-age children (6 to 19 years old) is the Third National Health and Nutrition Examination Survey (NHANES III, 1988-1994). African-American and Hispanic (Mexican-American) children were over-sampled to insure sufficient numbers for race and ethnic specific comparisons. In this study, air-conduction audiometric thresholds were obtained at 500, 1000, 2000, 3000, 4000, 6000, and 8000 Hz for 5,915 children in randomly-selected communities across the United States. Pure-tone averages (PTA), based on the speech frequencies (500, 1000, 2000 Hz) and on higher frequencies (3000, 4000, 6000 Hz) to assess the impact of noise exposure, have been computed separately for """"""""better"""""""" and """"""""poorer"""""""" ear. Multivariately adjusted odds ratio (OR) estimates of relative risk and 95% confidence intervals (CI) have been produced using logistic regression models. We have found that hearing impairment (better ear, low frequency PTA) is increased for young age, low family income, Mexican-American ethnicity, and fair or poor health status. In addition, we have examined the tympanogram tracings from this study and categorized children with flat tympanograms as likely to have otitis media with effusion (OME). The majority of these school-aged children are likely to have suffered from conductive hearing loss for long periods of time. This year, we completed a paper describing the prevalence, risk factors, hearing levels, and performance on standardized cognitive tests for the children with OME versus those with normal tympanograms. The children with flat tympanograms were younger, more likely Hispanic, with lower household income, and much more likely to have had a history of frequent ear infections. After adjusting for household income and race/ethnicity, we found generally lower cognitive test scores. However, these results reach borderline significance (p=.12) only for children aged 12 to 16 years. We concluded that the tympanogram data from NHANES III do provide objective evidence of increased rates of OME to help explain the increased hearing threshold levels of Hispanic school-aged children in the United States. Regarding other accomplishments, a member of the staff published a paper together with colleagues at Gallaudet University on the first wave of an Annual Survey of Deaf and Hard-of-Hearing Children and Youth in Puerto Rico. This survey began with the 1997-1998 school year and coverage has grown with each succeeding year. The goal is to characterize the children with hearing impairment in Puerto Rico in order to assist educators and researchers in the provision of improved services and health care. Also, a paper was published this year together with NICHD and university investigators on results of a neurodevelopmental follow-up for term and near-term hypoxic neonates randomized to inhaled nitric oxide (INO) who were at risk of death or extracorporeal membrane oxygenation. Twenty-two of the 157 children evaluated had sensorineural hearing loss (12 in the control group and 10 in the INO-treated group), a non-significant result. The conclusion from The Neonatal Inhaled Nitric Oxide Study was that INO is not associated with an increase in neurodevelopmental, behavioral, or medical abnormalities at 2 years of age. Two other studies are underway: 1) a study of familial risk for childhood hearing impairment using a maternally-linked file of births in Utah for 1978-1997, and 2) a collaboration with NIEHS and NICHD to analyze potential effects of in-utero exposures to DDE and PCBs on neurodevelopmental outcomes, with special emphasis on hearing assessed at age 8, based on the Collaborative Perinatal Project birth cohort.
