Prevalence of clinical referrals having hearing thresholds within normal limits

Abstract

Abstract

Objectives: To document the prevalence of clinically normal air conduction thresholds (0.5–4 kHz, bilaterally, ≤20 dB HL) among children and adults in a large audiology service and to estimate the prevalence of auditory processing disorder (APD). Design: Over a period of one year, clinicians implemented their usual protocol and recorded a brief history for those with normal audiometry. Study Sample: The number of people seen by the service was 2924 children (0–16 years old) and 4757 adults (17–100 years old). Results: Adults and school-age children were most commonly referred by their primary care doctor for difficulties listening in noise or following a conversation, and younger children by their home health visitor for speech production problems. Children tended to be referred on to speech pathology or APD clinics whereas adults were discharged. Conclusions: The prevalence of normal cases was 5.1% among the children and 0.9% among all adults. For younger adults (17–60 years, n = 1025), the prevalence was 4.0%. Based on comparison with those referred with hearing loss, we estimate the prevalence of APD among children and adults, defined as listening problems despite normal audiometry, to be about 0.5–1.0% of the general population.

Sumario

Objetivos: Documentar la prevalencia de umbrales aéreos clínicamente normales (0.5 – 4 kHz bilateralmente ≤20 dB HL) en niños y adultos en un servicio de audiología grande y estimar la prevalencia de trastornos de procesamiento central de la audición (APD). Diseño: Por un periodo de 1 año, los clínicos implementaron su protocolo acostumbrado y obtuvieron una historia breve de aquellos con audiometría normal. Muestra: la cantidad de personas vistas en el servicio fueron 2924 niños (0 a 16 años de edad) y 4757 adultos (17 a 100 años de edad). Resultados: Por lo regular, los adultos y los niños en edad escolar fueron referidos por su médico de contacto primario por dificultades para escuchar en ruido o para seguir una conversación, y los niños pequeños fueron referidos por su visitador de salud por problemas en la producción del lenguaje. La tendencia fue que los niños fueran referidos al terapeuta del lenguaje o clínicas APD, en tanto que los adultos eran dados de alta. Conclusiones: La prevalencia de audición normal fue de 5.1% entre los niños y 0.9% entre los adultos. La prevalencia entre los adulos jóvenes (17-60 años, n=1025) fue de 4%. Basados en la comparación con aquellos referidos con hipoacusia, estimamos que la prevalencia de APD entre los niños y adultos, definida como problemas de escucha a pesar de una audiometría normal normal, es de 0.5 – 1 % en la población general.

Key Words::

• Hearing impairment
• Auditory processing disorder
• Children
• Otitis media
• Referral criteria

Acknowledgements

The research was funded by the intramural programme of the Medical Research Council. The data collection was made possible through the cooperation of the patients and staff of Nottingham Audiology Services and the ENT clinics of the Queen's Medical Centre. We would like to thank Karen Willis for her help with data extraction.

Portions of this paper were presented as: Hind S.E., Haines-Bazrafshan R., Benton C., Brassington W., Willis K. & Towle B. 2008. Service evaluation of percentage of clinical referrals without anomalous audiometry. British Society of Audiology, Short Papers Meeting on Experimental Studies of Hearing; York, UK.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.