R Mak

Disabling conditions refer to those diseases, disorders, and impairments that cause physical, mental or social dysfunction sufficiently severe to interfere with the ability of the child to lead a normal life or to benefit from a normal education.¹ Although usually regarded as severe and chronic, dysfunction can range from mild to severe, transient to permanent.

Disabling conditions are important not only because they disable the child but also because of the demand they make on those who care for the child as well as on the medical, educational and social welfare systems of the community. It is therefore in everybody's interest that disabling conditions are prevented altogether.

Terminology

This is confusing because of changes in the understanding of child development, in concepts of disability and rehabilitation, in society's attitude towards disabled people, and in the models of service delivery.

For this discussion, the following terms will be used in accordance with the definitions of the World Health Organisation (WHO, 1980)²:

'Disabling conditions' will include disorders and impairments. Children who have disabling conditions will also be described as 'disabled children'. 'Disablement' will encompass impairment, disability, and handicap.

Disability as An International Epidemic

Disability has become an international public health problem. It is estimated that there are some 500 millions disabled persons of all ages all over the world. According to a national sampling survey conducted in 1987, the People's Republic of China (PRC) has an estimated 8.17 millions of disabled children under 14 years of age. amounting to 2.66% of the population of children of the same age.³ In Hong Kong, the Central Registry for Rehabilitation (CRR), the official and only territory-wide attempt at documenting the number of disabled persons and disablements, is known to be plagued by problems of under reporting. According to the September 1996 report, there were a total of 14,080 disablements in children 0-14 years old registered. Assuming a minimal number of children with multiple disablements, then about 1.2% of the population of children under 15 years of age will have disability.⁴

To promote the rehabilitation and rights of disabled persons, the WHO published its International Classification of Impairments, Disabilities and Handicaps² in 1980 to facilitate the collection of relevant information on disabled persons. The United Nations proclaimed 1981 to be the International Year of Disabled Persons, and designated 1983-1992 as the United Nations Decade of Disabled Persons. Following this, the United Nations Economic and Social Commission of Asia and the Pacific declared 1993-2002 to be the Asian and Pacific Decade of Disabled Persons with the aim of promoting the wellbeing of people with a disability in this region. The Hong Kong Government, being a participant of this resolution, is committed to promote the rights of disabled persons and their integration into the community.⁵

Types of Disabilities

From experience at the child assessment centres (CACs) of Department of Health, the numbers of children with disability has apparently been increasing. Children under 12 years old referred to the CACs have more than doubled in the last 10 years, from 1,146 in 1986 to 2,569 in 1996. Children with speech delay and mild global developmental delay accounted for the bulk of the increase while those with severe disabling conditions have remained about the same (Fig. 1). This is likely to be the confluence of many reasons, including increased survival of children who would previously have succumbed, success of early detection programs, improved intervention services, parents more keen to bring forth less severe conditions for medical care, and perhaps better accessibility to CACs.

Figure 1 - Children with Disabling Conditions seen at Child Assessment Service, Department of Health

The official CRR adopted 7 categories of disablements for registration.⁴ Of the children 0-15 years old registered in 1996, the frequency of disablements were: 40% mental handicap, 20% physical handicap (includes only those conditions that affect mobility), 4-5% each of hearing impairment, mental illness (including autism) and learning difficulties, and 2% visual impairment. There were 3 maladjusted children and a number of 'other disablements' which possibly include speech disorders. These categories have since been revised to 9 separate categories after including autism, visceral disability, and speech impairment but excluding learning difficulties.⁵ In an urban city like Hong Kong where detection and intervention are possible, children with milder degrees of dysfunction are likely to be identified. Thus, the population of disabled children should be larger than that recorded by the CRR.

Using criteria similar to that of the CRR categories, Arran Street CAC found a similar distribution of disabilities among 2,521 children, 0-11 years old, assessed during the period August 1978 to June 1982 (Table I),⁶ Mental retardation was also the most common disability and occurred in 56.9% of children. Next was cerebral palsy, present in 18.7%. Severe-profound hearing loss was present in 6.4%, autism in 2.6% (7.1% if children with autistic features are also included), and blindness in 1.4%. In addition, there were 16.2% of children with specific speech disorders.

Although it is difficult to generalise the results from one region to another because of the diagnosis, severity of dysfunction, age of population; setting and other differences, a rough idea about the population of disabled children in the vicinity will be useful. In the PRC, childhood handicaps are classified into 5 categories. According to the survey carried out in 1987, of the 8.17 millions disabled children under 14 years old, 65.96% had mental retardation, 7.58% orthopaedic handicap, 14.20% hearing/language handicap, 0.17% psychosis, 2.22% visual handicap, and 9.87% multiple handicap (i.e. two or more types). Mental retardation is the most frequent childhood disability.³

Multiple disabilities
Multiple disabilities are common. Local reports include: many children with Downs syndrome having visual impairment and hearing loss in addition to their mental retardation;⁷ cerebral palsied children with epilepsy, mental retardation and behavioural difficulties;⁸ severe visual impairment, infections, nutrition, orthopaedic and other problems in children with severe neurodevelopmental disability;^9-10 intellectual impairment, visual perceptual problems and autistic features in children with neurofibromatosis I;¹¹ and many more experience in clinical practice.

Of 2,521 children assessed over a 46 months period at Arran Street CAC, two out of three children had more than one type of disablement.⁶ The majority of blind children (90%) and children with cerebral palsy (87%) had multiple dysfunction, as did 45% of children with mental retardation (all grades) and 37% of children with significant hearing loss. 0.5% were unfortunately affected by all four disabilities at the same time. Other commonly associated conditions include: hyperactivity, emotional problems, other physical conditions and epilepsy. 73% of autistic children were mentally retarded. In 1996, of 2,836 children assessed, 14.4% (11.5% of children referred for initial assessment and 20.7% of children who had follow-up assessments) had two or more handicaps. It is difficult to tell whether the number of children with multiple disabilities have actually decreased as the severity of disabilities included in the two studies were different. The official CRR in 1996 documented 9.6% of the 132,644 individuals of all ages registered to have two or more handicaps. ⁴ The situation specific for children is not known. The 1987 survey in the PRC found a similar 9.87% of the disabled children as having two or more handicaps.³

Disabling Conditions

In practice, it is useful to consider a disabling condition as belonging to one of two groups based on the severity of its interference with every day functioning:

(a) High seventy conditions
These conditions give rise to severe and permanent disability. Fortunately, they are uncommon. Most are neurological or neurodevelopmental conditions, e.g. cerebral palsy, severe mental retardation, autism, and degenerative brain diseases. An identifiable cause can often be found and therefore must be vigorously sought for. Although these conditions are rarely amenable to treatment, early detection is important not only to prevent progression of the disorder and development of secondary problems, but also because of the potential of improved outcome through special educational and habilitative services. Some indication of the frequency of these conditions is in Table II.

(b) Low severity conditions
These conditions give rise to disabilities of low severity, some of which may be transient. The degree of severity refers to its effects on every day functioning. For example, dyslexia is a mild disability in day-to-day activities but may be a severe disability in the educational sphere. Common conditions are developmental disabilities, minor defects and impairments, e.g. speech impairments, clumsiness, squints, myopia, and conductive hearing loss. An organic cause is unlikely to be found. It is therefore more profitable to focus on the child and go on with intervention towards agreed goals rather than wait for a cause and diagnostic label. The diagnostic process can continue in parallel with intervention. The frequency of some of these conditions is in Table III.

Using a test tool developed by Lee¹² for screening language delay in Cantonese-speaking children, Wong¹³ found 3% of 3 year-olds to have specific language delay, one of the common reasons for speech delay.

Behaviour and emotional problems are also common and reported to have a prevalence of 12-29%.^14-16 Many severe ones persist beyond childhood and cause much disability.¹⁷ Hence their importance. Luk¹⁸ in a two-stage epidemiological study in 1987 found a prevalence of 23.2% for significant behaviour disorders in 3 year-olds. The prevalence rate for hyperkinetic disorder was 0.78% and that for attention-deficit disorder 6.1% in Chinese school age boys,¹⁹ lower than that adopted by the DSM-IV.²⁰

Causes of Disabling Conditions

Any condition that impairs the function of the central nervous system is a potential disabling condition. Familiar ones are neurological or neurodevelopmental disorders that lead to high and low severity disabilities. Psychological and psychiatric conditions (e.g. conduct disorders, separation anxiety disorders) can be equally disabling. Conditions not affecting the brain can disable through psychological effects (e.g. disfiguring scars, dysmorphic features, severe dwarfing) or by imposing physical limitations (e.g. asthma, cardiac disease, Duchenne muscular dystrophy, juvenile chronic arthritis).

Determining the cause is important for prevention. Causes of disabling conditions are usually considered as being prenatal (e.g. genetic and chromosomal disorders, intrauterine infections, maternal smoking and drugs ingestion), perinatal (e.g. prematurity and complications, obstetrical problems, neonatal hyperbilirubinaemia), or postnatal (e.g. infections of the central nervous system, accidental and non-accidental injuries, and other forms of child abuse).

In Hong Kong, the most common handicap is mental retardation. At Arran Street CAC, of 1,732 children assessed to have intellectual impairment in 1978-1982, 23% had congenital anomalies (44% of which were Downs syndrome), 19% were born with low birth weight, 18% had perinatal problems (of which 60% were related to labour and delivery), and 45% had family history of the same disability.⁶ In 1986, using a hierarchical approach, a probable cause or risk factor could be identified in 42.8% of children with mental retardation: 22.3% were prenatal, 14.2% perinatal, and 6.4% postnatal. In the PRC, a 1994 report shows that the aetiology could be determined for 78% of children under 14 years old with mental retardation: 34% were prenatal, 11.9% perinatal, and 33% postnatal.²¹

Cerebral palsy is the second common handicap. Wong⁸ reported that 59.7% of cases were due to perinatal causes, mainly hypoxic-ischaemic encephalopathy or hyperbilirubinaemia, and only 16% were due to prenatal and postnatal causes. Thus 78% of children had identifiable causes. At the same time, Ko²², based on cerebral palsied children assessed at Arran Street CAC, reported that 6.6% had congenital malformations, 31.8% low birth weight, 26.3% birth asphyxia, 8.4% severe neonatal jaundice, and 11.4% had meningitis/encephalitis. Other postnatal causes included accidental head injury and gastroenteritis.

Whatever the cause, children born premature or with low birth weight are known to have higher incidence of high and low severity disabling conditions. At a well-equipped and well-staffed perinatal intensive care centre in Melbourne, Australia, of 108 ELBW infants (birth weight < 1000g) born 1977-1982, 29% had one or more major disabilities at age 2 years.²³ The disabilities were cerebral palsy. developmental delay, blindness and sensorineural deafness. In VLBW (<1500g) survivors, 20% had minor disabilities (hyper- or hypotonia, visual impairments correctable by corrective lenses, conductive hearing loss, and minor anomalies). Hyperactivity and attention-deficit disorder were present in 11% at age 1 year and 43% at age 2 years. The disability rate of ELBW babies born at tertiary centres was about one third of those born at centres with inadequate perinatal intensive care.²⁴

In Hong Kong, VLBW survivors are now followed up jointly by the paediatric units of respective neonatal intensive care units and the child development/assessment centres (CACs) in a joint surveillance program. 17% had neurological impairments at 18 months corrected age.²⁵

Rehabilitation

Rehabilitation is a goal-orientated and time-limited process aimed at enabling an impaired person to reach an optimal mental, physical and/or social functional level, thus providing her/him with the tools to change her/his own life (United Nations World Programme of Action concerning Disabled Persons). However, the term Rehabilitation is not satisfactory when applied to children, since most disabled children are affected early in life and thus do not have normal abilities to regain. Rather, they need to be trained to develop even basic skills. For them, the term habilitation is thus more appropriate.

Habilitation has four aspects: identification, assessment, intervention and prevention. All of them have to be considered when managing a child with a disabling condition.

Concept of disability
Central to habilitation is the concept of disability held by those who provide habilitation. The traditional medical perspective is reflected in the International Classification of Impairments, Disabilities and Handicaps.² The concept consists of a linear progression from disease to handicap summarised as follows:

Disorder → Impairment → Disability → Handicap

According to the model, impairment and disability are neutral and objective results of disease whereas handicap is the result of society's adverse valuation of the individual's disability. Accordingly, intervention has focused on increasing function at the disability level (therefore decreasing the deficit or dysfunction) in order to prevent handicap.

The concept of disability has since become modified. It was found that the severity of the disability is not the sole determinant of handicap. Most important of all, children are no longer perceived to be passive recipients of external stimuli. They interact actively and reciprocally with the environment (physical and social) to construct their own development, i.e. not only is the child's brain plastic, development is also plastic.²⁶ Habilitation is thus an active and on-going process. Periodic assessments are for updating intervention goals and programmes. This is essentially a 'strength' model whereas the traditional medical model was a 'deficit' one.

Identification

Presentation
Gross defects are obvious from birth. The majority of severe neurodevelopmental conditions are apparent to parents early in the child's life and it is often the parents themselves who initiate medical intervention. Disorders that involve the immature brain are likely to interfere with the emerging basic competencies in different areas of development. The result is often developmental delay or deviation, including diminished or altered responsiveness to environmental and social stimuli. Young infants are likely to present with feeding difficulties, excessive irritability, and floppiness. Older infants and toddlers may, in addition, present with delayed development (e.g. motor and speech delay). For preschool children, speech delay is the most common presentation. Disorders of later childhood and adolescence may involve more discrete areas of behaviour, e.g. overactivity, somatic complaints or forthright discipline and conduct problems. ²⁷

Detection by the paediatrician
Low severity conditions are often not apparent to parents although they may suspect that something is wrong. Paediatricians can often detect these conditions opportunistically during consultations for other reasons by listening carefully and seriously to parents' concerns, by being alert to invisible disabilities (e.g. hearing loss, emotional problems), and by selectively conducting bedside developmental testing when developmental progress is of concern. For paediatricians in primary care practice, questionnaires are becoming available as a first line or adjunct 'screening aid' in the detection of developmental disabilities. Common presentation and observations for detection are in Table IV.

Emotional and behaviour problems are 'invisible' or 'hidden' disabilities. Paediatricians are known to under-identify them, especially in young children and children with disability, often despite voiced parental concerns.^14,28 To make matters worse, many children although diagnosed, are not referred for appropriate service or receive no or inadequate treatment. Practical checklists and guidelines can be very helpful in improving the detection of psychiatric problems in children.²⁹

Screening & surveillance programs
These programs are secondary or 'selected' prevention activities applicable to whole populations. Whereas the simple bedside developmental test/screen/assessment carried out as part of everyday clinical paediatrics is a 'screening' technique in the 'common' sense of the word, classical 'Screening' tests have well-defined criteria to meet before becoming qualified as such. The population to be screened is normal children, from which those individuals who already manifest that particular disabling condition has been excluded. Hong Kong's mass screening of all newborns detected congenital hypothyroidism 1:3041 newborns and glucose-6-phosphate dehydrogenase deficiency in 4.4% males and 0.3% females.³⁰ Neonates are also examined for congenital anomalies but there is gross under-reporting. Screening for visual and hearing impairments in preschool and school age children are conducted as part of surveillance programs.

Surveillance programs encompass all the activities that are necessary to continuously monitor the status of the child. It includes the combined observations and findings of those who come into contact with the child. These observations and findings may include the result of Screening/screening tests conducted by whoever has the appropriate training and skill. Surveillance programs in Hong Kong include: the Department of Health's Comprehensive Observation Scheme (COS) for preschool children and the Student Health Service for school aged children; and the Education Department's Combined Screening Program for primary one students.

The Developmental Screening Test (DST) is part of the COS to mass screen for developmental anomalies. The tests were developed from the work of Field and Baber on the developmental progress of Hong Kong's children^31-32 and adopted for use in the COS since 1978. It has become entrenched as a familiar part of routine service at Maternal & Child Health Centres. Although it does not qualify to be a screening test in the classical sense, and increasingly early detection of problems by parents themselves have gradually lessened its screening role, the DST is still a useful test when the child's development is of concern. The COS detected physical and developmental anomalies in 3.8% of preschool children³³ while the Student Health Service after screening some 260,000 primary school students detected visual impairment in 20.4% and psychosocial problems in 5.0% of children.³⁴ The Combined Screening Program of the Education Department identified visual, hearing, learning and speech problems in 5-7% Primary One students.³⁵

While early detection is desirable, erroneous results can lead to much unnecessary parental anxiety and ill-feeling.³⁶ Thus, before embarking on screening, paediatricians should ensure that the screening tools are valid and that appropriate care, treatment and support services are available for the further management of the child and his family should the disabling condition be detected.

Children identified to have problems are referred to different speciality clinics and child development/ assessment centres for evaluation of their impairments. In 1996, common reasons for children to be referred to the CACs of Child Assessment Service (Department of Health) were delayed speech (37%), global developmental delay (30%), behaviour problems (10%), and suspected hearing loss (9%). 85% of children referred were under 4 years old.

Assessment

Assessment is a medical diagnostic and problem-solving process. It is thus essential to first establish what really is the problem and to whom does the problem belong. This is particularly relevant for low severity conditions where the child, his parents, teachers or doctors may all have different understanding of the problem. Frequently, it has existed for some time and the medical consultation is only now precipitated by a specific event, e.g. rejection by school. For the young child, it will be useful to document the complaint as perceived by his caregiver parent. This complaint will have to be specifically addressed even if it turns out that the problem is not with the child but with the perception of the parent.

Assessment process
An assessment sets out to define the child's abilities, disabilities, and developmental profile in physical, mental and social domains, to diagnose the underlying disorder, to find its cause(s), and to deal with all attendant illnesses, associated conditions and complications. The functional areas assessed are usually those as listed in Table V. Clinical investigations are a part of the process. Assessment of children with multiple disabilities requires the coordinated effort of multiple disciplines. Since parent-child relationship (e.g. attachment) is important, especially for the young child, the functional status of his family should also be evaluated. An essential component of assessment is to identify risk factors, including psychiatric or psychosocial problems in parents. Assessment for purpose of intervention will have to take into consideration the prevailing model(s) of intervention. While the 'ecology' model appears attractive, training and education programs in Hong Kong are traditionally child-centred and train discrete areas. e.g. gross motor, fine motor, language and speech.^37-38 Liaison between paediatrician and therapists, childcare workers or teachers will be helpful in refining an intervention program to suit the child's individual needs.

Quantifying Disablement
Some impairments are more easily measured than others. To document the severity of hearing, visual and even intellectual impairments is not difficult, since there are reliable measures and universally acceptable scales to quantify the deficit. More complex impairments, e.g. autistic spectrum, speech impairments, are not so readily quantifiable. The assessment of speech, language, and reading difficulties is a particular problem, since most assessment tools are in English whilst most children speak the local Cantonese dialect and write in Mandarin. The Reynell Developmental Language Scales (Cantonese, Hong Kong version) is the only language measuring scale standardised for Hong Kong children 1-7 years old.³⁹

In these days of tight resources, individuals with different disabilities and different grades of severity compete for access to service. Unfortunately there is no universal measure of severity applicable across disabilities. Perhaps, a quality of life measure for children, comprising of objective and subjective components, may solve the problem in future.⁴⁰

Physical and mental health
Disabled children are at greater risk of psychopathology⁴¹ and frequently demonstrate challenging behaviours.^10,42 These may be aggression, social incompetence, anxiety-inferiority problems or attention disorders. Physically handicapped children with damage to the central nervous system have twice as many psychiatric problems as those without brain damage.⁴¹ The tendency to behaviour problems may be part of the primary disorder. It may also be secondary to altered parent-child and other interactional patterns from an early age, inadequate feedback about inappropriate behaviours and diminished expectation for appropriate behaviours, or a limited range of coping skills because of damage to the central nervous system. Challenging behaviours may well be the presenting problem, but more subtle emotional problems and poor self esteem may be overshadowed by the primary disability if they are not specifically looked for.

Children with disabling conditions are also at higher risk for illnesses, morbidity and mortality.

Follow-up assessments
Periodic review is necessary to monitor intervention results, ascertain developmental progress, update intervention goals and identify new risks and problems. As childhood is dominated by school life, assessments at key ages are necessary to define educational needs.

Intervention

Intervention refers to the systematic strategies employed to help the disabled child to function as independently as possible in a world of non-disabled children. Included are: physiotherapy, occupational therapy, speech therapy, psychotherapy, preschool training, educational programmes, community services and family support to help parents (and other family members) adapt as best as possible to having a disabled member of the family.

Not all disabling conditions require intervention. An assessment is an interactive experience for the child and parents with the paediatrician. For some, it will be an intervention in itself. However, if an intervention program is deemed desirable and feasible, then realistic and acceptable programs must be recommended. For children with low severity disabling conditions, it may be more fruitful to implement intervention and work towards agreed and realistic goals while diagnosis continues in parallel. For high severity disabling conditions, many will have no cure. Often attractive and unproven alternative therapies abound. Thus when prescribing rehabilitation services for children, paediatricians will need to be critical about the effectiveness, goal, outcome measure and duration of therapy of particular programs. In the case of physiotherapy and occupational therapy for children with motor disabilities, although "no evidence indicates that these therapies directly improve the specific motor impairment of the child", these programs empirically can help the child compensate for the disability or adapt to it as he grows and develops.⁴³

Parent involvement & support
Since children, especially young children, are dependent on their parents, parental (or family) involvement is indispensable for the successful habilitation of any disabled child. The earlier the involvement, the better. Parents want to be told, as early and in as sensitive a manner as possible, about the disabling condition, including its cause, preventive measures, its effects on the child's development and functioning, and the possible outcome. Diagnostic labels often have powerful implications and stigmatising connotations for patients and parents far beyond what professionals can envisage. A diagnostic formulation or concise summary will be less subject to misinterpretation than a single diagnostic label or category of disability. While prediction of outcome is inadvisable, a prognosis, in terms of the best and the worst outcomes, is often helpful.

Parents want suggestions on what can be done and what they themselves can do to help the child improve. Paediatricians will need to help parents understand the goals of specific therapy (e.g. physiotherapy for an infant) and to develop realistic expectations about these therapies (e.g. for assisting the disabled child to adapt to a non-disabled world rather than curing the underlying disabling condition). Parents themselves will need support while they recover from the impact and adapt to having a disabled child as a member of the family, including resource information regarding the disabling condition and opportunity to meet with parents of children with similar disabling conditions.

Anticipatory developmental guidance and promotion of optimal physical and mental health of the child are also integral parts of current paediatric practice to promote an empowering partnership⁴⁴ with parents thus enabling them to make use of services and professional expertise according to their needs.

Service coordination
In Hong Kong, there are medical, social, educational (including developmental) and vocational services for disabled children, provided by at least five government departments, many medical and allied medical specialities in the Hospital Authority, numerous non-government agencies and by the private sector (Table VI). Children with multiple disabilities may have to go to several different service institutions. This is frequently confusing and taxing for parents who are already stressed. Children are also at risk of being lost in between different clinical specialties or from preschool to school age programs. At CACs, to minimise interfacing problems, one member of the multi-disciplinary team is designated to coordinate services and to plan for transition from one service to another.

Teamwork
Successful habilitation programs require the integrated efforts of all concerned: child, parents, paediatricians, teachers, and multiple different disciplines. To facilitate communication, paediatricians can provide clear, concise, and up-to-date written information to those involved in the child's habilitation program. Relevant information include: treatment goals and duration, follow-up plans, medications and their frequencies, effect of medications, suitability of exertion, activities to avoid, channel for communication, etc. Routine and ad hoc meetings can facilitate monitoring of the child's progress, updating of intervention plan, and improving teamwork.

Prevention

Prevention of a disabling condition depends on knowing the specific cause(s) for that condition and implementing appropriate measures at all levels of prevention. In Hong Kong, familiar measures to prevent disabling conditions include: genetic counselling and antenatal diagnosis (followed by termination of pregnancy) to prevent Downs syndrome; immunisation of young girls to prevent congenital rubella; treatment of hyperbilirubinaemia, screening for glucose-6-phosphate dehydrogenase deficiency, and education to avoid specified substances to prevent athetoid cerebral palsy and sensorineural hearing loss; careful monitoring and timely treatment of retinopathy of prematurity to prevent blindness, etc.

The Paediatrician's Role

Management of a child with a chronic disabling condition is a long-term commitment. The traditional medical model so successful for treating acute medical conditions is not suitable for the management of disabilities that can last a lifetime. Moreover, disabled children, like non-disabled children, are entitled to be healthy and happy. Therefore, in addition to treating the medical problems, involvement in the psychological and sociological issues around the child and family is inevitable. It will take the paediatrician that bit more effort to merge curative and preventive measures in managing the developing child holistically in the context of home, school and community. For this, the paediatrician is in an excellent position to make sense of the plethora of habilitative services available in Hong Kong when recommending a dynamic habilitation program for each child, so that children with disabling conditions, although disabled, can enjoy optimal health and emotional well-being.

References

1. Forfar JO. Demography, vital statistics and the pattern of disease in childhood. In Campbell AGM & McIntosh N, editors. Forfar & Arneil's Textbook of Paediatrics, 4th edition. Churchill Livingstone, 1992:14-6.

2. World Health Organisation. International classification of impairments, disabilities and handicaps. World Health Organisation, Geneva, 1980:27.

3. Chen J ,Simeonsson RJ. Prevention of childhood disability in People's Republic of China. Child Care Health Dev 1993;19:71-88.

4. Half-yearly statistical report of the Central Registry of Rehabilitation. Rehabilitation Division, Health & Welfare Branch, Hong Kong Government. September 1996 Report:2-13.

5. White paper on rehabilitation: Equal opportunities and full participation - a better tomorrow for all. Health & Welfare Branch, Hong Kong Government, 1995:112.

6. A study of handicapped children assessed at Arran Street Clinic. Child Assessment Service, Medical & Health Department, Hong Kong Government, 1983:11-8.

7. Chang KC, Mak R. Major structural abnormalities and functional disabilities in preschool children with Downs syndrome in Hong Kong. HK J Paediatr 1993;10:96-102.

8. Wong V. Cerebral palsy - diagnosis and etiology. In Hsu LCS, editor. Proceedings of a symposium on Cerebral Palsy 1987. Duchess of Kent Children's Hospital at Sandy Bay, Hong Kong 1987:4-5.

9. Kwok SK, Ho PC, Chan AK, et al. Ocular defects in children and adolescents with severe mental deficiency. J Intellect Disabil Res 1996;40(4):330-5.

10. Chan AKH, Tse PWT. Problems associated with severe neurodevelopmental disability. HK J Paediatr 1994;11:139-42.

11. Lee FMY, Lam CCC, Lau IKC, et al. Neurodevelopmental problems in preschool children with neurofibromatosis I. HK J Paediatr 1995;12:77-80.

12. Lee PWH, Luk WL, Bacon-Shone J, et al. The developmental language screening scale: a validation and normative study. HK J Paediatr 1990;1:7-22.

13. Wong V, Lee PW, Lieh-Mak F, et at. Language screening in preschool Chinese children. Eur J Disord Commun 1992;27(3):247-64.

14. Costello EJ, Edelbrock C, Costello AJ, et al. Psychopathology in pediatric primary care: the new hidden morbidity. Pediatrics 1988;82(3):415-24.

15. Brandenburg NA, Friedman RM, Silver SE. The epidemiology of childhood psychiatric disorders: prevalence findings from recent studies. J Am Acad Child Adolesc Psychiatry 1990;29(1):76-83.

16. Ho TP. Child Psychiatry in primary care. HK Practitioner 1997;19(5):245-54.

17. Cohen P, Cohen J, Brook J. An epidemiological study of disorders in late childhood and adolescence: II. Persistence of disorders. J Child Psychol Psychiatry 1993;34:869-77.

18. Luk SL, Leung PW, Bacon-Shone J, et al. Behaviour disorder in preschool children in Hong Kong. A two-stage epidemiological study. Br J Psychiatry 1991;158:213-21.

19. Leung PW, Luk SL, Ho TP, et al. The diagnosis and prevalence of hyperactivity in Chinese schoolboys. Br J Psychiatry 1996;168(4):486-96.

20. American Psychiatric Association. Diagnostic & statistical manual of mental disorders. 4th edition. American Psychiatric Association, Washington D.C. 1994:48-113.

21. Zou QH, Lei ZW, Zhang ZX. An epidemiological study on etiology of mental retardation [abstract]. Chung Hua I Hsueh Tsa Chih 1994;74(3):134-7.

22. Ko L. Cerebral Palsy - an overview. In Hsu LCS, editor. Proceedings of a symposium on Cerebral Palsy 1987. Duchess of Kent Children's Hospital at Sandy Bay, Hong Kong 1987:3-4.

23. Wong PY, Yu VYH, Bajuk B, et al. Infants weighing less than l000g at birth II: Late disability. HK J Paediatr 1985;2:125-30.

24. Yu VYH. Results of neonatal intensive care in the very low birthweight infant. HK J Paediatr 1986;1:56-74.

25. Working group on neonatal service and neonatal transport, Hong Kong Hospital Authority and Child Assessment Service, Department of Health, Hong Kong Government. Developmental outcome of very low birthweight babies born in Hong Kong [abstract]. J Paediatr Child Health 1997;(Suppl)1:S22.

26. Sameroff AJ. Models of development and developmental risk. In Zeanah CH Jr, editor. Handbook of infant mental health. Guilford Press, New York 1993:3-13.

27. Luk SL, Lieh-Mak F. Child psychiatry in Hong Kong. J Obstet Gynecol 1985;Sep/Oct:15-8.

28. Steffenburg S, Gillberg C, Steffenburg U. Psychiatric disorders in children and adolescents with mental retardation and active epilepsy. Arch Neurol 1996,53(9):904-12.

29. Pearce J. Child health surveillance for psychiatric disorder: practical guidelines. Arch Dis Child 1993;69:394-8.

30. Lam STS, Yuen MLM, Mak WP, et al. Neonatal screening for congenital hypothyroidism and glucose-6-phosphate dehydrogenase deficiency in Hong Kong. HK J Paediatr 1986;1:26-33.

31. Field CF, Baber FM. Growing up in Hong Kong; a preliminary report on a study of the growth, development and rearing of Chinese children in Hong Kong. Hong Kong University Press 1973.

32. Baber FM, Chan CW, Hutchison JH. Screening Hong Kong's preschool children: the Hong Kong Developmental Screening System for preschool children (0-5 years). Department of Paediatrics, University of Hong Kong, 1982.

33. 1994 Department of Health Annual Report. Department of Health, Hong Kong Government 1995:84.

34. Hong Kong Review of Rehabilitation Programme Plan (1994/5-1998/9). Rehabilitation Division, Health & Welfare Branch, Hong Kong Government, June 1996:20-2.

35. Tse LY. Health screening of school children in Hong Kong [abstract]. J Paediatr Child Health 1997,(Suppl)1: SY28.

36. Tsui MKM. Lee JWK. Lam STS. Parental reaction of false positive screening test for congenital hypothyroidism. HK J Paediatr 1994;11:128-32.

37. Lo PH, Chan CW, Wong CFK. Beneficial effect of early intervention on children with developmental delay: objective evaluation of 10 years' experience. HK J Paediatr 1995;12:52-67.

38. Ballard KD. Assessment for early intervention: evaluating child development and learning in context. In Mitchell D and Brown RI, editors. Early intervention studies for young children with special needs. Chapman & Hall, London 1991:127-59.

39. Manual of the Reynell Developmental Language Scale, Cantonese (Hong Kong) version. The Society for Child Health & Development 1987:11-4.

40. Lindstrom B. Quality of life for children and disabled children based on health as a resource concept. J Epiderniol. & Community Health 1994;48:529-30.

41. Seidel UP, Chadwick OF, Rutter M. Psychological disorders in crippled children. A comparative study of children with and without brain damage. Dev Med Child Neurol 1975;17(5):563-73.

42. Rogers SJ. Observation of emotional functioning in young handicapped children. Child Care Health Dev 1991;17:303-12.

43. American Academy of Paediatrics. Committee on Children with disabilities. The role of the pediatrician in prescribing therapy services for children with motor disabilities. Pediatrics 1996;98(2):308-9.

44. Appleton PL, Minchom PE. Models of parent partnership and child development centres. Child care Health Dev 1991;17:27-38.

45. Paneth N, Kiely J. The frequency of cerebral palsy: a review of population studies in industrialised nations since 1950. In Stanley F and Alberman E, editors. The epidemiology of the cerebral palsies. Spastics International Medical Publications, London 1984:46-56.

46. Macfarlane A. et al. Child Health: the screening tests. Oxford Medical Publications, Oxford, 1989.

47. Cullinan TR. The epidemiology of blindness. In Miller S, editor. Clinical Ophthalmology. Wright, London 1987:571-8.

48. Gillberg C. Autism and related behaviours. J Intellect Disabil Res 1993;37:343-72.

49. Roeleveld N, et al. The prevalence of mental retardation: a critical review of recent literature. Dev Med Child Neurol 1997;39:125-32.

50. Hutchison T. The classification of disability. Arch Dis Child 1995;73:91-3.