1. Introduction

Chapter editor: Huibert Jan Simonsz

a. The EUSCREEN study

Mission

The EUSCREEN study compares the cost-effectiveness of paediatric vision and hearing screening programmes in Europe and has developed a cost-effectiveness model that can be used to assist with introduction, modification or disinvestment of a screening programme in a country, taking local circumstances into account, such as professionals available to screen and existing screening pathways.

A pilot study showed that there are vast differences between paediatric vision and hearing screening programmes regarding professionals involved, tests and thresholds used, age of the children screened, funding sources and so forth, and that data on these programmes are often unavailable1.

Collection of data

Paediatric ophthalmologists and paediatric otolaryngologists as well as audiologists and professionals who organise and perform screening in countries that participate in the European Union’s Horizon 2020 research and innovation programme, were invited to participate in the study and report on the state of screening in their country. Several other countries also expressed an interest in the study and evetually five additional countries supplied data2. An extensive, detailed questionnaire was developed for this purpose. These representatives provided data on their countries’ demography, existing screening programmes, coverage/attendance, tests used, follow-up/diagnosis, treatment, benefits and adverse effects.

Initial conclusions

The survey showed that there is substantial variation in hearing and vision screening programmes. The tests used, types of professionals involved in screenings, definitions of target conditions, frequency and location of testing and diagnostic pathways differ significantly between, and even within, countries. Monitoring and quality assurance are not routinely or systematically performed, even in countries with otherwise well-organised screening programmes. These issues make it very difficult to compare the effectiveness and cost-effectiveness of screening programmes. The lack of monitoring perpetuates the large diversity among screening programmes in Europe. Also, there is little to no communication between countries concerning screening programmes.

We have developed an interactive cost-effectiveness model to facilitate the comparison of different hearing and vision screening programmes. The model can calculate the most cost-effective and affordable way to screen children in each country or region, taking local circumstances into account: existing provision of preventive healthcare to children, availability of professionals who could screen, available budget and priority given based on prevailing healthcare of children. It should be noted that accuracy of the cost-effectiveness is highly dependent on the quality of the input data.

Alongside the development of the model and informed by its preliminary predictions, a hearing screening programme has been implemented in three counties in Albania and a vision screening programme in Cluj County in Romania. Both are High Middle Income Countries (HMICs) who do not have these forms of screening yet. Information gathered by thsee implementation studies has been used to validate and calibrate the model and also provide additional qualitative data on challenges and practical issues not covered by the model.

 

b. Development and purpose of this manual

This manual is a product of the EUSCREEN study and contains a generic strategy for implementation of child hearing and vision screening programmes. This strategy has been developed based on analysis of existing screening programmes, model calculations, expert opinion and experiences with the aforementioned implementation studies.

This manual is a complimentary resource to the EUSCREEN cost-effectiveness model: the model compares different hypothetical screening programmes to calculate the most cost-effective programme for a specific country or region. The manual subsequently serves as a practical strategy guide for implementing said programme. The model and manual are therefore complementary.

 

c. Outline and target audiences

This manual should serve as a useful companion for stakeholders such as professionals deciding to implement a programme, persons or teams managing screening programmes, as well as healthcare policy makers and governmental healthcare administrators.

The manual consists of five parts. Part I provides background information on hearing and vision screening and, because of its general nature, is likely to be of interest to all readers.

Part II deals with establishing a framework for hearing and vision screening programmes and should be of interest to governments and policy makers. These chapters describe the implementation process on a strategic level, based on scientific evidence and data collected within the EUSCREEN study. This section of the manual provides an overview of things to consider and investigate before using the odel.

Parts III and IV are practical guides for factors to consider in the implementation of hearing and vision screening programmes respectively. These parts of the manual will be of most use to management teams. These chapters describe the implementation process on an operational level and provide information on what to consider when implementing a screening programme. The information is based on evidence collected within the EUSCREEN study, such as the observations from the implementation of hearing and vision screening in Albania and Romania respectively.

Part V covers communication and monitoring of child vision and hearing screening programmes. These may be the most important chapters of the manual, as the main conclusion of the EUSCREEN study was that, even most countries where screening programmes are otherwise well-organised, appear not to have systematic monitoring systems: data on these programmes are generally reported to not be easily accessible or completely unavailable.

Note that information in the general parts of the manual – chapters not specifically about either hearing or vision screening – applies to both hearing and vision screening, unless specifically stated otherwise.

For a concise introduction to the general concepts of screening, this document published by the World Health Organization in 2020 is a recommended read for policy-makers and public health professionals. The document describes various aspects to consider before starting, continuing or stopping a programme. It also goes into the operational, monitoring and evaluation aspects.

 

d. Definition and history of medical screening

Medical screening has been defined as “actively seeking to identify a disease or pre-disease condition in individuals who are presumed and presume themselves to be healthy”3.

Medical screening is screening offered to all persons within an identified target population; defined for example by age, sex or risk. This is different from diagnosis following a patient’s presentation of symptoms4The objective of screening, in general, is to identify an unrecognised disease or condition. In case of paediatric vision and hearing screening, the objective is to identify functional sensory losses as early as possible.

A screening programme can be either universal or targeted. A universal programme offers screening to all in the target population, while a targeted programme only offers screening to those in the target population who are considered to be at greater risk for the condition being screened for. The advantage of targeted screening is that it costs less, but the disadvantage is that a substantial number of persons with the target condition may be missed. Which option is the most cost-effective will mostly depend on the prevalence of the condition among persons not considered to be at greater risk.

Historically, screening became practically possible when the following conditions were met5

  • establishment of a theory of screening
  • availability of simple, valid and acceptable tests
  • effective treatments
  • widespread access to healthcare

Although there were earlier initiatives that could, in retrospect, be qualified as screening, large-scale population screening began during the inter-war years to identify latent tuberculosis in children, by means of radiological examination. The term ‘screening’ originates from the fact that the X-ray images were viewed on a screen. With new technology becoming available, the decades following World War II were marked by an extensive proliferation of screening programmes. Radiography for tuberculosis was extended to the whole population and screening programmes were initiated for a variety of afflictions such as syphilis, diabetes, glaucoma, anaemia, obesity, visual defects, hearing loss, hypertension and heart disease6.

Since the early 1960s, screening of newborns for various diseases has also become common, beginning with Guthrie’s phenylketonuria (PKU) test7.

In 1968 the World Health Organization (WHO) published screening criteria8 (see chapter 2a) and nowadays, screening programmes are widespread in most High Income Countries (HICs). Screening programmes are especially common for different forms of cancer as well as for a wide variety of other diseases9.

In the last decades of the past century, screening programmes have also begun to draw criticism, mainly focused on ethical and psychological aspects, the relation between benefits and harms and (cost-)effectiveness10 11.

 

e. Child vision and hearing screening

The United Nations’ Convention on the Rights of the Child recognises the right of all children to “the highest attainable standard of health” and to an education which supports “the development of the child’s personality, talents and mental and physical abilities to their fullest potential”. The World Health Organisation’s 2021 World Report on Hearing further stresses the important role of hearing screening and early intervention to enable the optimum development of a child with hearing loss and includes a worldwide Call to Action. Both vision and hearing problems may go unnoticed by parents. . In addition, early identification and treatment of vision and hearing problems have been shown to lead to better outcomes. Screening for vision and hearing problems in children are therefore considered important. 

 

i. Vision screening

There are several types of vision screening: newborn vision screening (see chapter 7) targets severe sight-threatening ocular diseases such as cataract, neonatal ocular infections, corneal opacities and ocular tumours. The common causes of low vision in children, such as refractive error or strabismus or amblyopia develop or change after the neonatal period, and therefore should be screened for later.

Beyond the neonatal period the detection of amblyopia is the primary target condition because it needs to be treated in early childhood to avoid permanently reduced vision. It is also the most common cause of low visual acuity in childhood12. Amblyopia is a loss of vision mostly affecting one eye due to lack of adequate visual experience during the critical period of visual development. The reported prevalence of amblyopia varies, depending on study population and the definition of amblyopia used, but overall international prevalence estimates range from 1% to 5%13 14. 15% of children under 12 years of age have been shown to have significant refractive errors to cause a significant reduction in uncorrected vision15. These conditions are therefore sufficiently common to justify screening programmes.

If amblyopia is left untreated and later in life vision in the other eye is impaired, having an amblyopic eye may make the difference between a normal life and bilateral visual impairment.  The treatment for amblyopia in childhood is simple, low-cost, highly successful with life-long improved visions16 and will protect many of those treated from future visual disability17.

Amblyopia is asymptomatic in young children and rarely noticed by parents, except when caused by large angle strabismus or when bilateral and severe. It is much more easily treated in early childhood (before 7 years of age). Without early screening amblyopia is rarely detected until it is too late to be easily treated18. Amblyopia is rarely disabling in childhood, but children with low vision due to uncorrected high refractive errors are likely to be socially and educationally disadvantaged19. The goals of vision screening are therefore to identify and correct poor vision in childhood due to amblyopia and significant refractive errors.

Screening for amblyopia by measurement of visual acuity at the age of 4, 5 or 6 years is standard in almost all countries in Europe20. Other forms of vision screening in childhood are:

  • risk factor screening (which targets risk factors for amblyopia, not low vision itself);
  • screening of at-risk groups (children born prematurely, or those with disabilities or special educational needs have a higher prevalence of visual defects so they may be targeted specifically, more frequently or with more specific or in-depth testing);
  • screening in later childhood. Screening for visual defects beyond seven years of age is not covered in this manual because amblyopia is difficult to treat by this time.

There are many factors that make decisions of how, when, and how often to screen surprisingly complex, and with very different cost-effectiveness implications. Evidence shows amblyopia treatment is more successful when undertaken before the age of seven years21, therefore it is desirable to screen children as early as possible. However, in children younger than four years the rate of reliable VA testing may be too low for screening to be cost-effective, because a much larger percentage of children will need to be tested again or referred to diagnostic assessment. For children under four years, sensitivity and specificity as well as PPV are much lower than for older children. Visual acuity screening is therefore recommended in children no younger than four years and no older than six years22. However, screening may need to be offered to older children who may have relocated from a region without vision screening and have not been screened before they were six years old.

Since the early 2000s, screening for risk factors for amblyopia has been advocated instead of measuring visual acuity to establish the diagnosis of amblyopia. Risk factors for the development of amblyopia are strabismus, which is conspicuous for the parents in most cases, and refractive error, especially when strong glasses are needed to correct them. However, there are many issues which make the apparent advantages of this approach less clear than they may seem. Arguments for and against screening for amblyopia versus screening for risk factors for the development of amblyopia are covered extensively in chapter 8.

 

ii. Hearing screening

Undiagnosed or late-diagnosed hearing loss in children can have severe negative impact on development of effective language and communication. Unrecognized childhood deafness not only affects speech, language and communication development, but also social and emotional development, mental health and family relationships. The disability implications range from mild to severe, depending on the degree of hearing impairment, but can lead to significant educational underachievement which may result in an economic burden to society. Early identification and intervention can lead to better language skills, lower educational costs, and increased lifetime productivity.

The prevalence at birth of bilateral permanent sensorineural hearing loss with hearing thresholds greater than 40 dB is approximately 0.1-0.2% and that number increases to 0.2%-0.3% by the age of nine. The World Health Organization defines disabling hearing loss as “hearing loss greater than 40 dB in the better hearing ear in adults and a hearing loss greater than 30 dB in the better hearing ear in children”. Permanent hearing loss in newborns may be caused by genetic disorders, infectious diseases, or complications related to birth and the neonatal period.

Intervention for hearing loss varies with the type and degree of hearing loss, but the most common interventions are hearing aids and/or cochlear implants. Both types of treatment are feasible in very young children; yet for successful rehabilitation, children using these devices and their parents require intensive support by audiologists, teachers of the deaf, speech therapists and other healthcare or specialist education providers. Before early identification and intervention became possible, children with severe or profound hearing loss typically attended special (often residential) schools for the deaf. As early diagnosis, technology and appropriate interventions improved and became available for many children with hearing loss, attending mainstream education became more widespread.

With modern technology, objective hearing screening devices allow healthcare providers to feasibly and accurately identify hearing loss in newborns. Many countries, regions, and hospitals across the world have implemented newborn hearing screening (NHS; see chapter 5) targeted at early detection of sensorineural hearing loss. All newborns may be screened using the same test protocol (type and timing of the hearing test and retest). In certain subpopulations, such as infants treated in a neonatal intensive care unit (NICU), it may be relevant to apply a special protocol. Important considerations in these infants include the much higher prevalence of hearing loss, and the detection of auditory neuropathy spectrum disorder (ANSD).

The prevalence of hearing impairment (HI) in children increases with age. This increase can be caused by delayed onset HI, undetected mild HI that has progressed or acquired HI due to infections, trauma and other causes. Further, children may have relocated from a region without NHS, never having had their hearing screened previously. In fact, around half of all school-age children with hearing loss may be detected later in childhood. These children can be detected by preschool- and/or school-age hearing screening (chapter 6).

By far the most relevant disease in infancy and childhood with regard to hearing loss, is otitis media. Otitis media with effusion (OME) is very common during the first six years of life and may cause a conductive hearing loss of, on average, 25-40 dB. Although OME is usually transient and will resolve within weeks or months, it has a tendency to recur or become chronic. A mild hearing loss may be the only symptom in young children and this may go unnoticed. Treatment depends on the severity of the hearing loss, in one or both ears, and its duration. The point prevalence of OME is highly variable, ranging from 1 to 30%23. Suppurative otitis media may become chronic and result in a permanent conductive hearing loss. The prevalence of chronic otitis media is likely to vary considerably worldwide, depending on therapeutic options under various healthcare conditions24 25. They need, in addition to the audiological assessment, also an otological examination and possibly treatment.

next chapter

 

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