Research into the incidence and prevalence of people with communication disorders in less developed countries is a new field of study and tends to be impairment related (Pleasonton 1994 Kersner et a! 1995). In the absence of locally collected data many locally produced articles and publications resort to using extrapolated data from the more developed countries of the world (Amedofu et al 1993,1994, Nannyonga-Musoke 1993), as illustrated in the previous section.
National surveys in Nigeria and other less developed countries, on the incidence and prevalence of people with communication disorders, are sparse, poorly documented and therefore difficult to access. Different methods have been utilised but most address the issue non-specifically, through identification of a medical or educational grouping, with very little specific information concerning the proportions within groups who might have communication disorders. The few studies that do target people with communication disorders concentrate on patterns of etiology in relationship to recommended care procedures.
For Example Obiako and Izuora (1983) undertook a two year study of 150 children with ‘speech disorders' seen at the University of Nigeria Teaching Hospital between June 1979 and June 1981. Although such a study does not give information about general incidence and prevalence, it confirms that such children do exist in Nigeria and th a t they have sought help from the medical services.
The results of the study show that a similar variety of causes and degree of impairment, contribute to ‘speech disorders’ there, as they do in the rest of the world. They describe different kinds of^speech defects*under mainly physiological headings:
-damage to the central nervous system in 95 cases -loss of hearing in 42 cases
-damage to orgamof speech in 8 cases -delayed physical development in 3 cases -psychological factors in 2 cases
Chapter 1. Literature Reviev
This leads to some disparate groupings, for example mental retardation with cerebral palsy, and must have presented complications when deciding where to place children with multifaceted underlying factors. The resulting ‘speech disorders’ are predominantly either dysarthria or dyslalia which are clearly defined in the paper, but would be difficult to translate into present day perceptions of those terms.
Akapati (1986) argues th a t the prevalence of ‘communication disorders’ in developing countries is similar to anywhere in the world. Obiako and Izuora (1983) agree and conclude from their study th a t the pattern of ‘speech defects’ in Nigeria is similar to other parts of the world. However they observe that attitudes towards the people concerned differ markedly and comment that :
"whereas the Nigerian Mother starts to worry only when her child's speech disorder is so serious thot he connot com m unicote verbolly, her counterport in developed countries feels concerned with the slightest deviotion from normol mony porents ore unowore thot speech defects con b e corrected" pp 88
Such perceptions will undoubtedly effect any incidence and prevalence studies.
A later more detailed study from Enugu by lloeje and Izuora (1991) concerning the pattern and prognosis of speech disorders among children expands on the categories of children represented. Of 1105 children with neurological disorders seen in the hospital over a 3 year period 41 boys and 39 girls had ‘speech problems’. Dyslalia, defined as something which may be:
"of orgonic origin. This d e fe ct is chorocteristic of children w ho hove on obnormolly lorge tongue.o cleft polote or those who suffer from molocclusion of the teeth. Also tongue tie coused by on obnormolly short linguol frenum restricting the m ovement of the tongue,is sometimes blom ed for orticulotory distortion." pp 90.
was still the most common problem, and 32.5% of the 80 children were mentally retarded. A poor attendance and follow up rate was recorded.
A different approach by Thorburn (1991) reveals a different perspective where ‘speech’ is listed as a disability type, but it is noted that it is usually secondary to another disability. Here the data show that a ‘speech’ disability has an overall prevalence rate of 1.3%
Kersner, M. Mahon, M. and Nzama, S. (1995) recognise the importance and complexity of collecting epidemiological data on ‘communication disorders’ in developing countries, and th a t such information is vital
"in order for speech and language therapy provision to meet the needs of children adequately' pp 3
They undertook a survey in Zimbabwe, utilising existing speech and language therapy service provision as recommended by Hartley (1986). The results identify 7,121 children who have a ‘communication problem’, 3,978 of these children are reported to be receiving special teaching or therapy, while 2,883 are on the waiting list for intervention. They claim these numbers far exceed those reported by the Zimbabwean Ministry of Health in 1992 in a survey that identified 648 people in the category “speech and hearing disability” . They suggest th a t this lower level of identification may be due to a lack of differentiation between adults and children and the use of a less detailed identifying label, i.e. ‘speech and hearing disability’ in contrast with the comprehensive list of ‘communication problems’. The survey shows that the most frequently reported ‘communication problem’ is one associated with learning disability. They conclude that it is apparent from the study that the need for speech language therapy services supercedes available personnel.
The different parameters of the study by van Amstel et al(1993) which may be more in keeping with the local perception of disability, looked only for the inability to walk, see or hear, excluding other forms of physical disability, intellectual disability and disability as a result of aging which were considered to be inevitable and
"therefore not worthy of serious consideration' pp 317
The results of this study inevitably showed a much reduced prevalence rate , a mere 0.46%, very low in comparison with the estimates from more developed countries.
Puri (1989) reports th a t in 1960 the Indian government invited Dr. Martin Palmer from USA to study the magnitude of speech and hearing problems in India. According to Puri (1989) based on some surveys. Palmer estimates that 5% of the Indian population require the attention of speech and hearing specialists.
Chapter 1. Literature Review
IMPAIRMENT RELATED STUDIES.
Small surveys, targeting specific client groups offer information which can be useful in incidence and prevalence studies. Such surveys tend to concentrate on groups with a physiological common denominator, such as hearing impairment, physical impairment, mental impairment, and collect information about etiology, severity and demographic factors, (Holborow et al (1982) McPherson et al (1993) Nannyonga-Musoke (1993)). UNESCO (1988) question the relevance of collecting impairment related data as a basis for planning and delivery of educational provision and it is possible that such classification has limited relevance to the development of rehabilitation services.
Saunders and Miles (1990) and Carey (1995) also point out the limitations of such surveys reminding us that:
"Disabilities can only be defined by their context" pp 2 Saunders and Miles (1990)
"..the least of their problems is the actual impairment..' pp 12 Corey (1995)
They argue that service development should take priority and data should be derived from existing services. They point out that there is also an ethical dilemma concerning locally collected survey data, as it is likely to increase local expectations of service, and this is often not forthcoming. Coleridge (1993) says:
"It scarcely needs pointing out that doing o survey with no follow up or service delivery is o very cruel blow to those identified: o survey roises expectotions of o reosonoble improvement in their lives ond should b e done only os port of o generol plon for service delivery "pp 109
Publication of service based surveys in less developed countries appears sparse. An example would be Baldwin et al’s (1989) CBR survey at Kibwesi Kenya, but this gives little specific information about people with communication disorders. It is likely that there are a number of unpublished surveys which could give relevant information. For e x a m p le ^e unpublished annual report of the Speech and Hearing Clinic of the Special Education Department of the University of Ibadan, Hartley (1982) analyses the nature of the case load in terms of, numbers of clients in different impairment groups, services offered in relation to observed needs, and makes recommendations for future development of the services of the clinic in
consultation with parents families and other professionals. This follows a similar pattern of evaluation as recommended in Rapid rural appraisal by Annett and Rifkin (1995).
In spite of their limitations, impairment related surveys continue to be carried out. Commonly identified groups are cognitive impairment, hearing impairment and physical impairment and in the absence of other data, they do provide some useful information. Information gathered in relation to hearing impairment, because o f its close relationship to communication disorders is considered in more detail, to illustrate some of the difficulties and limitations of such studies.
H earing Im p a irm e n t re la te d s tu d ie s .
A number of studies have been carried out in several African countries into the prevalence of hearing impairment and reported by Hearing Network News of the Hearing and Impairment Research Group (HIRG) in Liverpool. The results of these studies, along with others reported by Hearing Network News can be found in Table 4. It is not easy to calculate how much of the large discrepancy seen in the prevalence levels can be explained by the type of survey used, or the parameters and methods adopted, let alone by true variations of prevalence due to demographic and other local factors.
T a b le 4 In cid en ce and P revalence s tu d ie s fo r h e arin g im p a irm e n t in LDCs.
Date C o iin trv Age P re v a le n c e R eferen ce Comments 19 8 7 Swaziland 5 -1 4 3% mild. 1% moderate and severe Hearing Impairment Research Group(1992) (HIRG) Single most important factor otitis media 1 9 9 2 Gambia 2 - 1 0 .27% severe and profound Smith and Hatcher ( 1 9 9 2 ) 1 9 9 2 Kenya 6% screen failures HIRG Oct. (1992) Bal & Hatctwr
Unilateral 3.7% Bilateral 2.4% 1 9 9 3 Ghana 8% screen failures Amedofu ( 1 9 9 4 ) 1 9 9 2 Nepal 5 + 16.6% Hearing Impairment Research Group (HNN) March 1992 prevalence refers to failed screening /earpalhology. Corxjude 35% preventable. No.l .disatsllit/ in Nepal. 1 9 9 3 China 0 .1 8 % HNN Oct 1 9 9 3 severe hearing loss 1 9 9 2 Aboriginal 15% Ear pathology 1 9 9 2 * 3 Namibia infants 0.6% Pleasonton 3 0 :1 0 0 0
Chapter 1. Literature Review
Smith and Hatcher (1992) note th a t researchers have conducted few population based studies on the prevalence o f deafness or hearing impairment in sub-saharan Africa, the studies that do exist focus on children attending schools for the deaf or special clinics. They conclude from the various surveys reported, th a t there are 1.2 million people with
moderate to severe hearing loss in Africa and 3.9 million with a mild hearing loss. This would be .3 % and .9% prevalence rate, if they are referring to sub-saharan Africa, a relatively low figure taking into account the higher prevalence rates of causative illnesses such as measles, rubella and meningitis reported by Holborow e t al (1982) and Pleasonton (1994). The latter refers to information reported in ‘The Namibian’ (1994) giving information concerning the number of reported cases of malaria in 1993 as 149,000 and 546 cases of meningitis between October 1993 and April 1994. She hypothesises that this high prevalence, together with the fact th a t treatment for these diseases frequently involves the use o f ototoxic drugs, must result in a larger population of hearing impaired people than would be found in countries where these diseases are rare.
MacWhite (1993) asks if hearing impairment should be measured at all in less developed countries, but Saunders and Miles (1990) feel th a t the details revealed by these surveys, such as the causes of hearing impairment, provide information which is very valuable to the community where they were conducted, and this information can have positive effects on the planning of a service. The process of searching for people with hearing impairment can also serve to raise the awareness level of th a t community and identify client groups.
"In most cases the interest e n g en d ere d by conducting the survey is associated with some chang e, in Western terms, of services offered, even if this chang e is not sustainable." pp7
Problems arise when the figures obtained in these small surveys are used to calculate more general incidence and prevalence rates. For example, Bai and Hatcher (1992) found a 6% prevalence rate for hearing impairment in their sample of 5,368 children from the Kiambu district of Kenya. This is significantly different to the estimated figures extrapolated from Enderby and Philipp (1989), but this figure could be used to estimate the size of this population group elsewhere, for example, in England, where it would, according to
locally collected data, be grossly inaccurate. Similarly in Nigeria, where, based on the premise that 40%.of the population is under 16, UNESCO (1990.) it would indicate an estimated potential of 2 million children suffering from hearing impairment alone.
Holborow (1982), indicates that a possible 49% of his sample of deaf children had a hearing loss due to technically preventable causes. By combining and comparing these two pieces of information it might therefore be possible to surmise th a t 980,000 o f the estimated 2 million children with hearing impairments in Nigeria had losses due to preventable causes and base an expensive programme of care on this information. Such generalisations are open to many pitfalls, not least, in this case, because demographic differences are not catered for.
As an alternative to specifically related impairment surveys, some studies relate to the services that have developed to assist, such as:
Special E d u catio n R elated S tu d ies
A survey carried out by the Nigerian Federal Ministry of Education (1986), concentrated on information about registered Institutions offering some form of training to disabled children. It aimed to explore the number of children receiving special education in Nigeria and estimate how many actually required such services. The survey documents the different categories of handicap reported, and tries to evaluate the rate at which services are developing in different states.
In each of the six categories of disability identified by the Federal Ministry of Education, i.e. Auditory, visual, physical, emotional, mental retardation and learning disabilities, one would expect to find a significant percentage of cases with a ‘communication impairment’, in some categories, such as ‘auditory’ or ‘mental retardation’ , this is likely to be substantial. There is however no information in the survey documenting this aspect.
Chapter 1. Literature Review
In conclusion :
- there is limited and inconclusive evidence gathered locally/nationally on the incidence and prevalence of communication disorders in less developed countries.
- the studies that exist are impairment related and generally do not identify people with communication disorders.
- the studies are inadequate and ill-represented.
1 .2 .3 . DISABILITY PERSPECTIVE: People with communication disorders viewed