Número y presupuestos de programas sociales

This updated review confirms the conclusion from the 2007 HTA report12_{that, because of a marked}

variability in the design, methodological quality and the results of the existing studies, it is not possible to draw strong conclusions about the performance of individual test types for use in SES.

Moreover, there were significant differences in the technical characteristics of some of the evaluated devices even when they belonged to the same screening modality (e.g. in the audiometry-based category there were two computer-based devices, one of which involves joysticks, etc., to help children respond, whereas the third one was a hand-held device). This is not surprising given that the studies included in the 2007 HTA and the current update span a period of 30 years. Interpreting their results together, even in the context of a narrative synthesis, requires careful consideration of the differences between the evaluated tests, which, in some cases, might be too great to justify such an approach. Combining the results from more modern devices with those from older ones and making general conclusions based on all the studies included in a particular category may be inappropriate. The performance of currently available tests is of interest to policy-makers.

With these caveats in mind, the findings from the current update, interpreted in the context of the 2007 HTA report,12_{could be summarised as follows:}

l We were able to identify a limited number of studies that provided additional diagnostic accuracy data for only the following categories of hearing screening tests: parental questionnaires, audiometry-based tests, TEOAE and AABR. No studies evaluating AABR were included in the 2007 HTA report.12

l Questionnaires had the poorest diagnostic accuracy compared with all other tests. The only study that directly compared a questionnaire with another test (TEOAE) supported this finding.22

l Audiometry-based tests had high specificity but variable sensitivity.

l Studies evaluating TEOAE reported variable sensitivity with wide CIs, whereas specificity estimates were relatively high and more consistent (with the exception of one study).29

l The study evaluating AABR reported high sensitivity and specificity.

The majority of the studies were conducted in countries without an established UNHS system and with variable health-care arrangements and, therefore, the reported results may have limited applicability to the UK context characterised with a well-established UNHS system, sensitised educational system and highly accessible and responsive health care.

Chapter 3

Diagnostic accuracy of the pure-tone

screen and HearCheck screener for identifying hearing

impairment in school children

Introduction

In the survey of practice reported in the 2007 HTA report12_{the test used for the hearing screen was}

in all cases the PTS but there was a wide variety of implementations of this, with different frequencies, pass criteria and retest protocols. Studies concerned with the relative accuracy (in terms of sensitivity and specificity) of alternative screening tests are difficult to compare and often flawed by their use of different referral criteria and case definitions. As reviewed inChapter 2, the 2007 HTA report12_identified

25 publications reporting comparative trials of alternative screens or tests for screening at school entry. Most studies were undertaken in populations where the prevalence of undetected hearing impairment was considerably greater than that likely to be encountered in a system where a UNHS programme has been introduced. These published data indicate that, using full PTA as the reference standard, the PTS test appears to have high sensitivity and high specificity for minimal, mild and greater hearing impairments; better than alternative tests for which evidence was identified. Spoken word tests were reported with acceptable levels of sensitivity and specificity but are variable in their implementation. OAEs, tympanometry, acoustic reflectometry, parental questionnaires and otoscopy were reported, with either variable or poor accuracy.

A new device, the HC screener, came onto the market in 2005 as a tool for screening for hearing impairment in adults in a general practice setting. It is hand held and has an automatic presentation of a series of tones at two frequencies and three levels: 1 kHz at 55, 35 and 20 dB HL, and 3 kHz at 75, 55 and 35 dB HL. It has potential to be a quicker test in the school setting but it has not previously been assessed as a tool for screening in children.

Objectives

In this chapter we use a two-gate case–control design32_to:

l estimate the diagnostic accuracy of the PTS and HC tests for discriminating between children with a hearing impairment (of any type) and children with no hearing impairment, using PTA results as the reference standard

l compare the diagnostic accuracy between the PTS and HC methods.

Measures of diagnostic accuracy are reported at the level of the ear and at the level of the child. From the outset we considered the ear-level analysis to be primary to the objectives addressed in this chapter because it directly addresses the question of the accuracy of the tests for discriminating between hearing and impaired ears. The child-level accuracy estimates are more relevant, however, for informing the refinement of the existing economic model of the benefits of a SES programme, reported inChapter 8.

Methods