Introduction
Hearing impairment is a handicap which can be corrected therapeutically and can be helped with amplification. It is usually associated with a loss of communication [1] and in the young children it will also impair the normal development of speech and language [2]. The poverty of language in school children also affects reading skills and diminished functional status [3]. Early childhood hearing impairment (HI) may have a negative effect on educational outcome and employment in adulthood [4]. Persons with HI are likely to have lower family incomes, less educated and unemployed [5]. Early identification of HI followed by a timely and effective intervention is necessary to minimize its negative effects on the development of cognition, psychological and verbal communication skills [6].
The main objective of this study was to determine the hearing level in Karachi’s school children between ages 5–15 years, to determine the prevalence of HI and to identify its causes of among these children.
Methods
A survey was conducted during 2008–2009 in 170 schools of Karachi. The prevalence of HI in Karachi’s school children between the ages of 5–15 years of both genders and studying in normal schools was estimated. There are 0.629 million children registered in 2,988 schools in Karachi. From each school, 30 children from different classes were randomly selected with total of 5,120 children in the sample. Hearing assessment was carried out using standard procedure with a portable audiometer. The threshold of hearing was measured at 250, 500, 1000, 2000 and 4000Hz, respectively, and data was recorded. Children were labeled as hearing impaired if they did not respond to tone in the range of 25 dB and below, in any frequency tested as per WHO protocol [7]. Children with HI were subjected to otoscopy. Later on, parents of children having HI were interviewed regarding ear discharge, family history of HI, drug history, noise exposure, and parent’s consanguinity.
Results
Among our sample of 5,120 children, 2,730 (53.3%) were male and 2,390 (46.8%) were female (male to female ratio 1.4:1). Most of the children (n=4,424; 86.4%) were found to have normal hearing i.e. < 25 dB, and 696 (13.6%) had some degree of hearing loss i.e. hearing threshold > 25 dB. There was no difference in prevalence of HI between males (14.1%) and females (13.0%). Among the 696 children who had HI, 616 (12.0%) had mild hearing loss (26–40 dB); 42 (0.8%) had moderate hearing loss (41–50) dB; 30 (0.6%) had moderately severe hearing loss (51–70 dB); and 8 (0.2%) children had severe hearing loss (71–90 dB). No child was profound deaf. Among the hearing impaired children most (88.2%) had conductive hearing loss, 58 (8.3%) had sensorineural hearing loss and 24 (3.5%) children had mixed type of hearing loss. A majority (61.2%) of children with conductive hearing loss had impacted wax in one or both ears; 78 (12.7%) children had unilateral or bilateral discharging ears suggestive of chronic suppurative otitis media. The less common findings were fungal infection (1.6%) and foreign body (1.3%). About 20% children had no positive finding on otoscopic examination.
Percentage distribution of children by gender and level of hearing
Discussion
In Karachi, HI in school children is 13.6%. Impacted wax was found to be the most common problem which can be very easily managed. The next common finding was history of ear discharge and it showed a very significant cause of conductive HI. We found that assessment of school children is useful to identify manageable HI. We recommend that ear hygiene among school children should be promoted. Similarly, ear infections should be promptly diagnosed and treated to avoid complications.
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