Prevalence figures for mild hearing impairments cannot be based on clinical data

Prevalence and risk factors for mild and high-frequency bilateral sensorineural hearing loss at age 11 years old: a UK prospective cohort study

OBJECTIVE

This study aimed to assess prevalence and risk factors for mild/high-frequency bilateral sensorineural hearing loss within a UK population of children at age 11 years.

DESIGN

Prospective birth cohort study.

STUDY SAMPLE

Repeat hearing thresholds were measured in 5032 children, as part of the Avon Longitudinal Study of Parents and Children (ALSPAC) at age 7, 9, and 11 years. Pregnancy, birth, and early medical history were obtained prospectively through parental questionnaires and medical records.

RESULTS

Twenty children had mild and seven had high-frequency bilateral sensorineural hearing loss, giving a combined prevalence of 0.5% (95% CI 0.4-0.8%). These children were more likely than the rest of the study sample to have been admitted to hospital at 6-18 months (OR 2.7, 95% CI 1.00-7.30). Parents of these children were more likely to have suspected a hearing problem when the children were 3 years old (OR 2.4, 95% CI 1.05-5.60).

CONCLUSIONS

This is the first UK prospective cohort study to investigate the prevalence of mild and high-frequency hearing loss. This study, which has the advantage of a large sample size and repeat hearing measures over a four year period, reports lower prevalence values than US cross-sectional studies.

Prevalence and etiology of congenital or early acquired hearing impairment in Eastern Finland

OBJECTIVE

The purpose of this study was to determine the prevalence and etiology of congenital or early acquired bilateral sensorineural hearing impairment (SNHI) in children born from 1988 to 2002 in the district of Kuopio University Hospital, Finland, and to compare the results with those from an earlier 14-year period in the same region and similar population.

METHODS

The data were collected retrospectively from Hospital Records. The degree of hearing impairment was based on average air conduction threshold calculated over the frequencies 0.5, 1, 2 and 4 kHz in the better hearing ear. Hearing impairment was classified as mild (≥ 20-39 dB), moderate (40-69 dB), severe (70-95 dB) and profound (>95 dB).

RESULTS

We identified 92 children with bilateral SNHI diagnosed before the age of 7 years. The overall prevalence and the prevalence for at least moderate SNHI was 2.1 per 1000 live births and 1.2 per 1000 live births, respectively. We found no differences in the prevalence of SNHI during both study periods. Etiology was genetic in 46%, acquired in 14% and unknown in 40%. Out of the genetic cases 74% were non-syndromic and 26% were syndromic. In comparison to the previous study there was a decline in the proportion of acquired SNHI and the proportion of genetic and unknown cause had increased. Six children in five families had homozygous 35delG mutation and six children in four families presented with a homozygous M34T mutation.

CONCLUSIONS

The prevalence of congenital or early acquired SNHI in the Kuopio University Hospital district area has not changed during a period of 29 years. Despite possibility to test the GBJ2 gene, the proportion of hearing impairment of unknown etiology remained high.

Self-rated mental health, school adjustment, and substance use in hard-of-hearing adolescents

This survey, "Life and Health-Young People 2005," included all 15/16-year-old adolescents in mainstream schools in the county of Orebro, Sweden. Just students with a slight/mild or moderate hearing loss were included. There were 56 (1.9%) "hard-of-hearing (HH) students with multiple disabilities," 93 (3.1%) students who were "just HH," 282 (9.7%) students with some "other disability than HH," and 2,488 (85.2%) students with "no disability." "HH with multiple disabilities" reported considerably higher scores for mental symptoms, substance use, and school problems than the "no disability" group. Those with "just HH" and those with "other disability than HH" had more mental symptoms and school problems than the "no disability" group but no significant differences in substance use. In conclusion, the combination of a hearing loss and some other disability strongly increases the risk for mental symptoms, school problems, and substance use. This group, thus, is an important target for preventive measures.

Hearing screening--aspects of epidemiology and identification of hearing impaired children

Mass screening of hearing in children is based on the concept of secondary prevention. In recognition of the importance of an early identification and intervention in children with congenital or early-acquired (i.e. neonatal period) hearing disability, numerous hearing screening programs have been introduced throughout the world. The devastating consequences of a congenital/early acquired hearing disability upon the speech, language, and social development of a child, and the estimated prevalence rates of at least 1-1.5/1000 live births of congenital permanent hearing impairment, represent an important health problem. The increase in the estimated prevalence of permanent hearing impairment in childhood, reaching at least 3.6-8.2% of live births at 5-9 years of age further emphasizes the importance of the problem. The delayed identification of children with congenital/early acquired hearing disability should result in the implementation of universal neonatal hearing screening, and the negative impact on the learning processes during school age from hearing impairment acquired throughout childhood seems to justify the introduction or maintenance of a hearing screening at school entrance. Implementation of efficient hearing screening programs throughout the neonatal period, infancy, or childhood should result in secondary prevention of this important health problem.

Aetiology and risk indicators of hearing impairments in a one-year birth cohort for 1985-86 in northern Finland

The aetiology and risk indicators of hearing impairments of all types and degrees were studied in a 1-year birth cohort of 8713 children from northern Finland. The subjects (7 years of age) included in the clinical and audiometric examinations were recruited by standard clinical criteria, i.e. suspicion of parents according to a questionnaire, abnormal hearing screening result or a hearing impairment noted in hospital records (n = 541), and by random sampling from among the 8172 not suspected (n = 1009). One-hundred-and-one subjects in the group suspected of having hearing impairment and 27 subjects in the random sample eventually had hearing impairment. The aetiology could be defined in only 44.5% of the cases, ear infections being the most common. In this relatively small series, only a few risk indicators (congenital anomalies, meningitis and a history of ear discharge lasting for over 1 month) could be shown to be associated with impaired hearing in a logistic regression analysis.