Differences between European birthweight standards: impact on classification of 'small for gestational age'.

We describe a quantitative and comparative review of a selection of European birthweight standards for gestational age for singletons, to enable appropriate choices to be made for clinical and research use. Differences between median values at term across standards in 10 regions and misclassification of 'small for gestational age' (SGA), were studied. Sex and parity differences, exclusion criteria, and methods of construction were considered. There was wide variation between countries in exclusion criteria, methods of calculating standards, and median birthweight at term. The lightest standards (e.g. France's medians are 255g lower than Norway's medians) were associated with fewer exclusion criteria. Up to 20% of the population used in the construction of the Scottish standard would be classified as SGA using the Norwegian standard. Substantial misclassification of SGA is possible. Assumptions about variation used in the construction of some standards were not justified. It is not possible to conclude that there are real differences in birthweight standards between European countries. Country-based standards control for some population features but add misclassification due to the differing ways in which standards are derived. Standards should be chosen to reflect clinical or research need. If standards stratified by sex or parity are not available, adjustments should be made. In multinational studies, comparisons should be made between results using both a common standard and country-based standards.

Participation of disabled children: how should it be characterised and measured?

PURPOSE: The aim of the paper is to explore the issues involved in measuring children's participation. METHOD: The concept of participation as encapsulated in the International Classification of Functioning, Disability and Health (ICF) is discussed as it applies to children. The essential components of any measure of children's participation are outlined, including participation essential for normal development and survival, leisure activities, and educational participation. Some existing instruments are briefly reviewed in terms of their coverage of the essential components and the adequacy of their approach to measurement. RESULTS: Key issues regarding the content of an adequate measure of participation include the need to consider the child's dependency on the family, and their changing abilities and autonomy as they grow older. Instruments may be most appropriate where they ask the child directly, implying use of visual as well as verbal presentation. Their focus should be on 'performance' such as whether and how often an activity is taken part in, and not incorporate degree of assistance within the measurement scaling. CONCLUSIONS: Currently available measures of children's participation all have some limitations in terms of their applicability across impairment groupings, whether the child can directly respond, and in the ICF components covered. The feasibility of developing measurement instruments of children's participation at different ages is discussed.

Injury outcome indicators: the development of a validation tool.

BACKGROUND: Researchers have previously expressed concern about some national indicators of injury incidence and have argued that indicators should be validated before their introduction. AIMS: To develop a tool to assess the validity of indicators of injury incidence and to carry out initial testing of the tool to explore consistency on application. METHODS: Previously proposed criteria were shared for comment with members of the International Collaborative Effort on Injury Statistics (ICE) Injury Indicators Group over a period of six months. Immediately after, at a meeting of Injury ICE in Washington, DC in April 2001, revised criteria were agreed over two days of meetings. The criteria were applied, by three raters, to six non-fatal indicators that underpin the national road safety targets for Canada, New Zealand, and the United Kingdom. Consistency of ratings were judged. CONSENSUS OUTCOME: The development process resulted in a validation tool that comprised criteria relating to: (1) case definition, (2) a focus on serious injury, (3) unbiased case ascertainment, (4) source data for the indicator being representative of the target population, (5) availability of data to generate the indicator, and (6) the existence of a full written specification for the indicator. On application of these criteria to the six road safety indicators, some problems of agreement between raters were identified. CONCLUSION: This paper has presented an early step in the development of a tool for validating injury indicators, as well as some directions that can be taken in its further development.

Development and validation of a tool to measure the impact of childhood disabilities on the lives of children and their families.

OBJECTIVE: Information on registers of children with special needs will be more meaningful if a validated measure of the severity of impact of a child's disability on life and family is included. DESIGN: We describe the development and initial validation of a parent-completed questionnaire (Generic Lifestyle Assessment Questionnaire LAQ-G) aimed at measuring such impact. RESULTS: Data were collected on 95 case children, representing various disabilities, and 65 control children without disability, and analysed for case-control, test-re-test and inter-reporter reliability. Multidimensional scaling techniques were then used to derive six domains, representing impact of disability in a structure analogous to the participation domains of the revised International Classification ICF (WHO 2001). CONCLUSIONS: Initial results suggest that the LAQ-G is a reliable measure of the impact of disability for children with a range of common disabling conditions.

Measure for measure: the quest for valid indicators of non-fatal injury incidence.

In this edition of Public Health, McClure and colleagues report on research that considered the criterion validity of indicators based on serious long bone fracture and length of stay in hospital. They found that neither were sensitive or specific indicators for serious injury as defined by an Injury Severity Score (ISS) of 16 or more. They contend that their study findings ' em leader strongly support a return to a measure similar in intent to that encapsulated in the original UK Green Paper em leader '. We contend that their analysis does not provide any empirical evidence to support their view that there should be a return to the Green Paper: Our Healthier Nation indicator. Furthermore, we consider the analyses that they carry out to validate both the Saving Lives: Our Healthier Nation and the serious long bone fracture indicators are flawed. We agree that national (or state) indicators are very influential. They encourage preventive action and resource use aimed at producing favourable changes to these indicators. However, each of the four non-fatal indicators considered in their analysis have problems. Formal validation of existing indicators is necessary and the following aspects of validity should be addressed: face; criterion; consistency; and completeness and accuracy of the source date. Taking into account the current national data systems in England, possible options for one or more national non-fatal unintentional injury indicators have been proposed in our paper. Furthermore, the International Collaborative Effort on Injury Statistics (ICE) Injury Indicators Group is about to embark on the development of a strategic framework for the development of valid indicators of non-fatal injury occurrence.

Creating a measure of impact of childhood disability: statistical methodology.

The aim of the study was to develop a statistical method to derive a domain structure for the development of an impact of disability index, using multidimensional scaling of questionnaire items and expert and non-expert judgement of severity based on standardised videos. The participants were parents of children with cerebral palsy, parents of children in mainstream schools and clinicians with expertise in cerebral palsy, all accessed through child health services in the north east of England. The methods to create a weighted, domain structure for use with the impact of disability index were developed. Multidimensional scaling techniques can be used to derive dimensional data structures. Standardised video material can be used to elicit expert judgements of severity of disability.

Why the government was right to change the 'Our Healthier Nation' accidental injury target.

We congratulate the current UK Government on their inclusion of accidental injury as one of the national targets in the White Paper: Saving Lives-Our Healthier Nation (OHN). We had concerns about the particular target that was proposed in the Green Paper: 'ellipsisto reduce the rate of accidents-here being defined as those which involve a hospital visit or consultation with a family doctor-by at least a fifthellipsis'. The limitations of this target were: firstly, it would focus attention on minor injury and so not reflect the main burden of injury; and secondly, that ascertainment of cases would be influenced by social factors as well as provision of service and access factors. The new target stated in Saving Lives also has its limitations since it will be influenced by service factors. This target is to reduce by 10% the rate of serious injury, defined as injury resulting in four or more days in hospital. We have proposed the use of an alternative indicator of unintentional injury occurrence, based on serious long bone fracture admitted to the hospital. This alternative indicator is based on the occurrence of serious rather than minor injury. It is likely that a high proportion of cases of these injuries can be identified from existing data sources. Ascertainment of cases is likely to be independent of social, service or access factors. Finally, these injuries are associated with significant long term outcomes including disablement, reduced functional capacity and reduced quality of life. It does have the limitation that it does not measure all serious injury. Such a measure is much more difficult to achieve. Further improvements to our proposed indicator could be made in a number of ways, through investigating an extended definition of the indicator to include a range of other serious injuries, improving the quality of existing data, making other data sources available, including outpatient data, and making serious injury a notifiable disease.

Increasing rates of cerebral palsy across the severity spectrum in north-east England 1964-1993. The North of England Collaborative Cerebral Palsy Survey.

OBJECTIVES: To report epidemiological trends in cerebral palsy including analyses by severity. DESIGN: Descriptive longitudinal study in north-east England. Every child with suspected cerebral palsy was examined by a developmental paediatrician to confirm the diagnosis. Severity of impact of disability was derived from a parent completed questionnaire already developed and validated for this purpose. SUBJECTS: All children with cerebral palsy, not associated with any known postneonatal insult, born 1964-1993 to mothers resident at the time of birth in the study area. MAIN OUTCOME MEASURES: Cerebral palsy rates by year, birth weight, and severity. Severity of 30% and above defines the more reliably ascertained cases; children who died before assessment at around 6 years of age are included in the most severe group (70% and above). RESULTS: 584 cases of cerebral palsy were ascertained, yielding a rate that rose from 1.68 per 1000 neonatal survivors during 1964-1968 to 2.45 during 1989-1993 (rise = 0.77; 95% confidence interval 0.2-1.3). For the more reliably ascertained cases there was a twofold increase in rate from 0.98 to 1.96 (rise = 0.98; 95% confidence interval 0.5-1.4). By birth weight, increases in rates were from 29.8 to 74.2 per 1000 neonatal survivors < 1500 g and from 3.9 to 11.5 for those 1500-2499 g. Newborns < 2500 g now contribute one half of all cases of cerebral palsy and just over half of the most severe cases, whereas in the first decade of this study they contributed one third of all cases and only one sixth of the most severe (chi(2) and chi(2) for trend p < 0.001). CONCLUSIONS: The rate of cerebral palsy has risen in spite of falling perinatal and neonatal mortality rates, a rise that is even more pronounced when the mildest and least reliably ascertained are excluded. The effect of modern care seems to be that many babies < 2500 g who would have died in the perinatal period now survive with severe cerebral palsy. A global measure of severity should be included in registers of cerebral palsy to determine a minimum threshold for international comparisons of rates, and to monitor changes in the distribution of severity.

Children are not goldfish--mark/recapture techniques and their application to injury data.

OBJECTIVES: Mark/recapture (or capture-recapture) is a simple technique commonly applied to estimate the hypothetical total (including undercount) in a register composed of cases from two or more independent and separately incomplete case lists. This paper seeks to illustrate serious drawbacks in the use of the mark/recapture technique when applied to injuries. SETTING AND SUBJECTS: Northumbrian children under 15 years of age who were seriously injured in motor vehicle accidents (MVAs) over a five year period ascertained from two data sources: police reports and hospital inpatient records. METHODS: Individuals (n) appearing in both police (S) and hospital (H) case lists are identified using various matching criteria. The separate and combined influence of age, sex, and casualty class (cyclist, passengers, pedestrians) on the probability of such matching is estimated using multivariate techniques. The hypothetical total incidence of child MVA victims (N) is calculated from N = (S x H)/n. MAIN OUTCOMES: Estimates of the incidences of "serious" injuries in MVAs under various conditions of stratification and matching. The overall procedure is tested for conformity with accepted criteria for valid use of mark/recapture. RESULTS: About one third of the 1009 police and 836 hospital records could be exactly matched. There were significant variations in matching proportions by class of accident (pedestrian v passenger v cyclist). This selective recapture or "heterogeneity" was not affected by sex, but was independently influenced by the age of the child. Further uncertainty was introduced when matching criteria were slightly relaxed. Estimates of the total population of children with serious injuries vary accordingly from 1729 to 2743. A number of plausible reasons why these two data sources might not be unbiased or mutually independent samples of the total target population are proposed as explanations for this heterogeneity. CONCLUSION: This typical example of two sample mark/recapture estimation in an epidemiological setting can be shown to violate virtually all the requirements for valid use of the technique. Very little can be deduced accurately about the scale or characteristics of an unobserved group by the use of mark/recapture applied to two overlapping health event registers.

The lifestyle assessment questionnaire: an instrument to measure the impact of disability on the lives of children with cerebral palsy and their families.

Suitable measures of health and morbidity are less readily available for children than they are for adults. We present a measure, which is used to describe the impact of impairment and disability on the lives of children with cerebral palsy and their families. The development of this measure involved data collected from 691 children with cerebral palsy contained within the North-East England Cerebral Palsy Register and born between 1960 and 1985. Uniquely, multidimensional scaling techniques were used to derive dimensions analogous with those described in the International Classification of Impairments, Disabilities, and Handicaps. We present the analyses undertaken to test the properties of the tool, which show that it is a reliable and valid measure of the disadvantages experienced by children with cerebral palsy.

Preventing childhood unintentional injuries--what works? A literature review.

AIM: The aim of this paper is to report on a systematic review of the world literature to provide information about the most effective forms of health promotion interventions to reduce childhood (0-14 years) unintentional injuries. The findings are of relevance to policy makers at a local or national level, to practitioners and researchers. METHODS: The relevant literature has been identified through the use of electronic databases, hand searching of journals, scanning reference lists, and consultation with key informants. RESULTS: Examples of interventions that have been effective in reducing injury include: bicycle helmet legislation, area wide traffic calming measures, child safety restraint legislation, child resistant containers to prevent poisoning, and window bars to prevent falls. Interventions effective in changing behaviour include bicycle helmet education and legislation, child restraint legislation, child restraint loan schemes, child restraint educational campaigns, pedestrian education aimed at the child/parent, provision of smoke detectors, and parent education on home hazard reduction. For the community based campaigns, the key to success has been the sustained use of surveillance systems, the commitment of interagency cooperation and the time needed to develop networks and implement a range of interventions. Education, environmental modification and legislation all have a part to play and their effect in combination is important. CONCLUSION: The design of evaluations in injury prevention needs to be improved so that more reliable evidence can be obtained. Better information is needed on process, so that successful strategies can be replicated elsewhere. There is also a need for literature reviews on effectiveness to be updated regularly and for their findings to be widely disseminated to policy makers, researchers, and practitioners.

Annual incidence of unintentional injury among 54,000 children.

OBJECTIVE: To enhance the case definition of unintentional injuries in childhood by applying an objective severity measure to fatal and non-fatal cases. DESIGN: A descriptive prospective epidemiological study of a defined resident childhood population (< 16 years of age) for a one year period, 1990. SETTING: Newcastle upon Tyne, England. Child population estimate for 1990 was 54,400. SUBJECTS: Resident children who died, were admitted to local hospitals, or attended local accident and emergency departments. OUTCOME MEASURES: Using recognised severity scoring systems (for example the injury severity score, trauma score) injuries were classified as severe, moderate, or mild. RESULTS: There were six deaths, 904 admissions, and 11,682 accident and emergency department attendances. All deaths, 25% of admissions, and 1% of accident and emergency attenders were classified as severe. The underlying determinants of severe injuries are different than those for all other injuries (for example age, social class). A comparison with a local survey in 1986 showed a 26% rise in hospital admissions, but no significant rise in the frequency of severe or moderately injured children. Comparisons with other international data showed higher rates of injury admissions and attendances for England, but no significant differences in the frequency of severe injuries. CONCLUSIONS: Objective severity scoring enhances the case definition of unintentional injuries in childhood by allowing for the identification, and, therefore, the more reliable ascertainment of severely injured children. This more completely ascertained set of population cases increases the accuracy of comparisons of injury frequency over time and by place, and, in addition, enhances our basic understanding about the epidemiological characteristics of childhood unintentional injury.

Preschool vision screening: a prospective comparative evaluation.

We have reviewed the results of a pilot study of preschool screening by orthoptists for vision defects which was introduced in Newcastle in 1987. We have compared the visual outcomes, at age 7 years, of children who were screened at age 3 years by either orthoptists, health visitors or general practitioners in three matched, geographically defined cohorts. Manifest, large angle strabismus presented at the same age, and in roughly equal numbers in each cohort. Orthoptic screening detected many more cases of amblyopia associated with microtropia and anisometropia, but the b overall amblyopia prevalence at age 7 years was similar in each cohort. This study does not provide evidence to support the nationwide introduction of primary orthoptic preschool vision screening, and highlights the need for a prospective treatment trial of amblyopia associated with microtropia and anisometropia.

Measuring exposure to injury risk in schoolchildren aged 11-14.

OBJECTIVE: To apply a measure of exposure to injury risk for schoolchildren aged 11-14 across a population and to examine how risk factors vary with sex, age, and affluence. DESIGN: Self completion questionnaire survey administered in schools in May 1990. SETTING: 24 schools in Newcastle upon Tyne. SUBJECTS: 5334 pupils aged 11-14, of whom 4637 (87%) completed the questionnaire. RESULTS: Boys were exposed to greater risk than girls in journeys to places to play outdoors; they took longer trips and were more likely to ride bicycles (relative risk 5.30 (95% confidence interval 4.23 to 6.64)) and less likely to travel by public transport or car. Younger pupils (aged 11-12) were less exposed to traffic during journeys to and from school: their journeys were shorter, they were less likely to walk (trip to school, relative risk 0.88 (0.83 to 0.94)), and they were more likely to travel by car (trip to school, relative risk 1.33 (1.13 to 1.56)) or school bus (1.33 (1.10 to 1.62)). Poorer children were exposed to greater risk than affluent children (from families that owned a car and a telephone): they were less likely to travel to school by car (relative risk 0.26 (0.20 to 0.33)) or to be accompanied by an adult (0.39 (0.32 to 0.48)). CONCLUSION: Injury risk data can provide useful information on child injury prevention and can be used to identify priorities and target resources for injury prevention on a citywide scale or for an individual school.

Measuring the frequency of "severe" accidental injury in childhood.

STUDY OBJECTIVE: The aim was to improve the epidemiological information concerning child accidental injuries which can be extracted from routine inpatient and coroners' inquest data. DESIGN: This was a retrospective study of coroners' inquest reports and inpatient case notes to undertake objective severity scaling and to extract basic data. This material was related to denominators from OPCS mid-year population estimates, to 1981 census ward populations, and to sociodemographic data collected in a local census in 1986. SETTING: The study population was derived from three north east health districts and their corresponding census enumeration districts. PARTICIPANTS: A stratified sample of 500 children aged 0-16 years from among residents admitted to hospital with accidental injuries in 1986 was studied, together with all accidental injury child deaths between 1980 and 1986; 94% of the relevant case notes were localised and extracted. MAIN RESULTS: When differentiated by injury severity there are major systematic differences in the basic epidemiology of child accidental injury by age and place of residence of victims as well as in the nature and causes of injuries sustained. CONCLUSIONS: Injury severity scores can be used to define a "severity" threshold, within the spectrum of injuries, leading to hospital admission or death. By ensuring complete ascertainment this technique can provide a more accurate case definition than crude admission rates for estimating the frequency of injury in a population of children.

Preschool vision screening.

Although a good case for preschool screening for vision defects can be made there is very little evidence that existing programmes are effective in practice. A comparative trial of three different methods of preschool vision screening is described. Some 7000 children initially aged 5 months (younger cohorts) and 30 months (older cohorts) in three matched areas entered the trial during 1987. During 18 months of follow up new visual and ocular defects among these children were ascertained through ophthalmology outpatients and from optician records. Screening at 35 months by an orthoptist based in the community is superior to conventional health visitor surveillance at 30 months and to an agreed programme of primary care screening for squint at 30-36 months as judged by screening sensitivity (100% v 50% v 50%) and the incidence of treated target conditions (17 v 3 v 5 per 1000 person years). A notable feature in the area served by the orthoptist is that 13 children received treatment for straight eyed visual acuity loss from among 1000 children whereas there were no such cases among 2500 in the comparison areas. In the younger cohorts (that is, screening at age 5-9 months) all three programmes showed equally poor results, only one of the eight treated target conditions arising from all 3500 younger children being screen detected.

Auditing community screening for undescended testes.

Different ways of auditing screening for undescended testes, using Hospital Activity Analysis data, hospital case notes, and community/general practice records are described. The cumulative orchidopexy rate per 1000 male births in successive birth cohorts is a simple tool for monitoring trends within a health district. Information gained from community/general practice records is valuable in highlighting problem areas in screening, such as the lack of clear diagnostic criteria and referral pathways.

Measuring child health inequalities using aggregations of Enumeration Districts.

In demonstrating health variations between different areas in a district, it is conventional to use local authority ward-to-ward variations. In rural districts, because wards have small, heterogeneous populations, this method is less useful. We have investigated alternative ways of showing variations in child health by using different aggregations of Enumeration Districts (ED) in a small, sparsely populated rural area. EDs were aggregated first by a cluster analysis based classification (Super Profiles) and second according to a material deprivation score (the Townsend score). Both methods of aggregation showed similar variations between areas in the proportion of babies with low birthweight, the proportion of teenage mothers, immunization coverage and six-week screening examination coverage. Both methods discriminated better than a straightforward ward-based analysis. Neither method was clearly superior to the other. It is concluded that for both epidemiological research and for health service information purposes, either of these methods of ED aggregation has definite advantages over ward-based analyses in rural areas.