Acceptability, benefit and costs of early screening for hearing disability: a study of potential screening tests and models.

OBJECTIVES

To show that hearing loss has such a high prevalence in the older population to justify screening, if effective and acceptable methods are available; and that population take-up and benefit can make a measurable outcome difference in quality of life.

DESIGN

A population study of people aged 55-74 years was undertaken. A clinical effectiveness study of differently organised screening programmes was carried out using a controlled trial to identify those who might benefit from intervention (and the extent of the benefit). A retrospective case-control study examined the very long-term (more than 10 years) compliance of patients in using their hearing aids after early identification and determined the extent to which early-identified hearing-impaired people have better outcomes than equivalent people identified later. An examination of the costs and cost-effectiveness of different potential screening programmes was also undertaken.

SETTING

A population study was designed in the UK, with specific stages being conducted in more depth on a sample of people from Nottingham and Southampton. The clinical effectiveness study was conducted in general practices in Nottingham and Bath using a systematic or opportunistic screen. The retrospective case-control study compared a group of early-identified hearing aid users, with control matched for age, gender and occupation, in Cardiff, Glasgow and Manchester.

PARTICIPANTS

In Great Britain responses were obtained for 34,362 individuals from the postal questionnaire as part of a population study, 506 were interviewed, 351 were assessed for benefit from amplification and 87 were fitted with a hearing aid. The clinical effectiveness study received 1461 replies from the first-stage questionnaire screen, with 306 people assessed in the clinic, of whom 156 were fitted with hearing aids. The retrospective case-control study traced 116 previously fitted hearing aid users, who had been identified by a screen, and then conducted a case-control using 50 of these for whom complete data were available, matching with two control groups of 50 people.

INTERVENTIONS

The major prospective interventions were to introduce amplification through offering people, with minimal hearing impairment, hearing aid(s) in a rehabilitative setting. In the population study, aids were offered as a monaural in-the-ear (ITE) hearing aid and in the clinical effectiveness study people who met the criteria were randomised to be offered two different ITE hearing aids to be fitted bilaterally. The retrospective case-control study used unilateral and bilateral hearing aids.

MAIN OUTCOME MEASURES

Prevalence of hearing problems and degree to which services meet need in 55-74-year age group. Public acceptability and individual benefits of hearing screening and intervention as a function of demographic and hearing domain-specific characteristics. Improvement in quality of life. Screening costs and cost-effectiveness as a function of proposed programmes.

RESULTS

It was found that 12% of people aged 55-74 years have a hearing problem that causes moderate or severe worry, annoyance or upset, 14% have a bilateral hearing impairment of at least 35 dB hearing level (HL) and only 3% currently receive intervention, through the use of hearing aids. Good amplification was shown to benefit about one in four of this 55-74-year-old population and the degree of hearing loss predicted benefit well. Overall, there was a strong correlation between benefit from amplification and from using hearing aids. Questionnaires and audiometric screens gave good screening operating characteristics. The systematic screening programme was more acceptable and gave a better response than the opportunistic. About 70% of those who were offered an aid accepted a bilateral fitting. This increased to 95% for those with > or =35 dB HL (averaged over 0.5, 1, 2 and 4 kHz in the better ear). The retrospective case-control study showed that long-term hearing aid use was low, unless hearing impairment was quite high (e.g. >35 dB HL). Those identified early had greater benefit through additional years of use/better adaptation to use than those of the same age and hearing impairment who were fitted with hearing aids later. Different screening programmes were modelled. The 35 dB HL better ear average hearing impairment level was found to be a good, robust and justifiable target group for screening and here the most efficient and practicable method was to use two questions in primary care concerning hearing problems and a hearing screen using a pure tone at 3 kHz 35 dB HL. The average cost of the screening programme was 13 pounds per person screened or about 100 pounds if treatment costs were included. Making the conservative assumption that identification gives an extra 9 years using hearing aids, the costs of screening and intervention were in the range of 800-1000 pounds per quality-adjusted life-year when using the Health Utilities Index and about 2500 pounds using the Short Form 6 Dimensions metric.

CONCLUSIONS

A simple systematic screen, using an audiometric screening instrument, has been shown to be acceptable to people in the age range 55-74 years, is likely to provide substantial benefit and may be cost-effective to those in that target group. Hearing screening appears to meet the National Screening Committee's criteria in most respects, provided screening is targeted at those with at least 35 dB HL better ear average. Based on the research carried out here there is sufficient evidence to support a larger and more definitive study of hearing screening. Further research into who should be referred for and benefit from audiological assessment and provision of hearing aid in a primary care trust setting is needed as is investigation into screening devices and the various aspects of introducing such a programme.