The Hearing Review Cross-Currents are staff-reviewed articles, features and news items that relate to hearing issues from a variety of sources and disciplines. If you are interested in a particular item, we encourage you to obtain a copy of the cited publication. —KES

Cost-Utility Analysis of the Cochlear Implant in Children
AK Cheng, HR Rubin, NR Powe, NK Mellon, HW Francis & JK Niparko
Profound deafness as a result of hair cell impairment occurs in approximately 0.3% of children younger than five years old. Today, more than 200,000 people have received cochlear implants. However, most U.S. health care plans fail to cover these devices reportedly because of a lack of data on cost-effectiveness. What is known, however, is that the “expected lifetime cost to society for a child with prelingual onset of profound deafness exceeds $1 million, largely because of special education and reduced work productivity.”

This paper investigates the cost-effectiveness of cochlear implants using three cost-utility measurements: Time Trade-Off (TTO), Visual Analog Scale (VAS) and Health Utility Index (HUI). The 78 children whose parents were queried in the study had an average age of 7.5 years and used their implant devices (Cochlear Corp.’s Nucleus-24 and Advanced Bionics’ Clarion) for 1.9 years.

Including direct costs such as reduced educational expenses, cochlear implants proved to be highly cost-effective and provided savings of $53,198 per child. The authors concluded that “Considering only direct medical costs yields cost-utility ratios of $9029 per QALY [quality-adjusted life-year] using the TTO, and $7500 per QALY using the VAS, and $5197 per QALY using the HUI…Medical interventions with a cost-utility less than $20,000 to $25,000 per QALY are generally considered to represent acceptable value for money, ie, cost-effective.” In comparison, the authors noted that defibrillator implants have a cost of $34,836 per QALY, knee replacement $59,292 per QALY, and adult cochlear implants $11,125 per QALY using the VAS. The range between costs in all three cost-utility measurements in the study were small ($5197-$9029), lending confidence to the results.

Direct medical cost ranged from $5197-9207 per QALY using the three utility measurements and the total cost per QALY was less than $0, prompting the authors to conclude that “The cochlear implant is extremely cost-effective, generating important health benefits in children at reasonable direct costs and providing a net savings to society.”

Jour Amer Med Assn (JAMA)
August 16, 2000: pgs. 850-856

Good Readers May Get Perceptual Lift
B Bower
Children who are good at detecting modulations or pitches of low-frequency sounds proved most adept at reading words and manipulating speech, say the results of a study conducted by Joel B. Talcott and colleagues at the Univ. Laboratory of Physiology, Oxford, England. Additionally, those children who were best able to spot changes in the motion of dots across a computer screen had the best spelling skills. This leads the investigators to believe that hearing and vision abilities separately influence children’s ability to read.

For the acoustic test in the study, children were presented with high- and low-frequency tones containing modulation, and were also asked to pronounce non-phonetic words (e.g., colonel) and nonsense words. They were also tested on the manipulation of speech sounds, like switching the first consonants of a word with the consonants of another word (e.g., “little” and “pup” to make “pittle” and “lup”). Low-frequency tone sensitivity coincided with higher scores on speech sound tests, even when accounting for the child’s intelligence and reading ability. High-frequency tone sensitivity did not coincide with higher scores.

Some researchers say the study suggests that children’s reading skills would benefit if instructors could find ways to help youngsters rapidly detect acoustic and visual stimuli. Other researchers say that, while visual and hearing processes obviously contribute to reading skills, it’s a “leap of faith” to make such conclusions.

The findings also suggest that dyslexia may not be a distinct neurological disorder, but rather a deficiency of hearing or vision combined with brain disturbances affecting sound and visual perception. This combination of deficit may cause some people to fall on the lower end of a performance continuum and be diagnosed as “dyslexic.”

Talcott et al.’s original paper appears in the Proceedings of the National Academy of Sciences (March 14, 2000).

Science News
March 18, 2000, Vol. 157: pg. 180