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Incidence and Demography of Non-Accidental Head Injury in Southeast Scotland from a National Database
Incidence and Demography of Non-Accidental Head Injury in Southeast Scotland from a National Database Robert A. Minns, PhD, FRCP, FRCPCH, Patricia A. Jones, MAppSci, Jacqueline Y-Q Mok, MD, FRCP(Edin), FRCPCH, DCH, RFP Background: This study utilized an existing national database of cases of non-accidental head injury (NAHI; also called inflicted traumatic brain injury [inflicted TBI] and shaken baby syndrome [SBS]) in Scotland to report the incidence, confidence intervals, and demography of such cases in Southeast Scotland. Methods:
This prospective population-based study was conducted from January 1998 to September 2006. Data from the Lothian region of Scotland, where there is known full ascertainment of infant head injuries, including NAHI, have been used to calculate the incidence rate for this region of Scotland, with government statistics providing the normal annual infant population as the denominator. A new Scottish Index of Multiple Deprivation (SIMD), which assesses a very focused area (data zone population size⫽750) and provides novel information about social demography for education, housing, employment, health, crime, income, and geographic accessibility to services, was applied to the identified cases of NAHI during this study period.
Results:
The mean incidence of NAHI in southeast Scotland for 8.75 years was 33.8/100,000 infants per year. The cases of NAHI were mostly located in the lowest 1 (or 2) quintiles for all SIMD domains (education, housing, employment, health, crime, income), although they had good accessibility to medical and other community services.
Conclusions: The incidence rates from this prospective study for NAHI are considerably higher than other published UK surveys and are not considered to reflect a cluster effect. The perpetrators in this study fit a strongly skewed profile aggregating to the lowest socioeconomic groups in the community. (Am J Prev Med 2008;34(4S):S126 –S133) © 2008 American Journal of Preventive Medicine
Introduction
B
rain injury results from less than 1% of all types of child abuse and occurs in 1.8% of all cases of physical abuse.1 Although only a small segment of the whole panoply of child abuse, non-accidental head injury (NAHI; also called inflicted traumatic brain injury [inflicted TBI] and shaken baby syndrome [SBS]) accounts for an overwhelming number of fatal or life-threatening injuries attributed to physical abuse of children aged ⬍1 year. Some 20% of NAHI are fatal, while serious sequelae of learning disabilities, motor disabilities, blindness, epilepsy, or organic behavioral problems occur in approximately 60% of those who survive.1,2
From the Department of Child Life and Health, University of Edinburgh (Minns, Jones, Mok); Royal Hospital for Sick Children, Lothian University Hospitals NHS Trust (Minns, Mok), Edinburgh, Scotland, United Kingdom Address correspondence and reprint requests to: Professor R.A. Minns, PhD, Department of Child Life and Health, Reproductive and Developmental Sciences, 20 Sylvan Place, Edinburgh EH9 1UW, UK. E-mail: [email protected].
The cost can be substantial to the child, his immediate and extended family, the pediatric services involved in his acute and chronic medical care, and expenses for civil and criminal proceedings. However, the real magnitude of the burden of NAHI for any population can be appreciated only by multiplying the overall financial and emotional costs for the individual case by the true incidence. The incidence figure is important in planning for resources to address these issues and to fund surveillance by child-protection teams, including health visitors, social workers, district nurses, general practitioners, and pediatricians. Few studies have examined the incidence of NAHI and addressed the social demography of those cases in the population. The true incidence is important to assess effectiveness of new research proposals or public health strategies in a scientific way. The most accurate incidence figures likely will be derived from prospective population studies, which require the number of infants in the population annually as a denominator. The social demography of the families of children in the population with NAHI will further focus prevention
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strategies to ensure that the intervention is targeting those families in the population at a high risk of NAHI. A prospective study was conducted to: (1) ascertain the precise incidence of NAHI in southeast Scotland; (2) compare these figures with figures obtained variously for other regions and parts of the country, including Scotland as a whole, England, and Wales; and (3) profile the cohort of infants with NAHI using a social demographic tool (the Scottish Index of Multiple Deprivation [SIMD]).
Patients and Methods Participating Centers A prospective study (active surveillance) was commenced in 1998 to assess the incidence and demography of NAHI in Scotland. All Scottish pediatric and general hospitals with pediatric wards, Accident and Emergency departments admitting children, neurosurgical/neurologic units, and intensive care units admitting children were consulted on a regular basis (monthly) by a data coordinator requesting details concerning any recently admitted infants with a provisional diagnosis of “suspected non-accidental head injury.” Patient details were transferred onto an SPSS database. For the collection of demographic and patient details, names and addresses were required but not included in the database. The study has both Local and Multicentre Research Ethics approval. There are 16 hospitals in Scotland with pediatric units (midyear 2005 population equals approximately 5,094,800) transferring information to this database.2 The General Register Office for Scotland provides government statistics (www. GRO–Scotland.gov.uk/). This website provides midyear population estimates for Scotland by gender, every age (by year), and administrative and Health Board areas. This provides the denominator for the incidence calculations. The total infant population (i.e., children aged ⬍1 year) at mid-2005 was 54,476. Figure 1 shows the infant population nationally and for the Edinburgh and surrounding area (Lothian region).
Case Definition Local investigators were required to complete a form for any child presenting with “suspected NAHI,” and specifically for
Figure 1. The infant population nationally and for Edinburgh and the surrounding area (Lothian region).
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any child with evidence of a subdural hemorrhage or retinal hemorrhage, alone or in combination.
Data Collection The form for data collection consisted of 153 items in 11 sections: (1) demography including postcode; (2) history (medical diagnostic background); (3) presenting symptoms; (4) presenting signs; (5) imaging (cranial and peripheral); (6) retinal findings; (7) other injuries (fractures, bruising, signs of contact); (8) severity of injury (measured intracranial pressure levels, duration of ventilation); (9) outcome (at hospital discharge and 6 months); (10) discharge diagnosis; and (11) degree of surety of diagnosis. The database notes whether a case conference for child protection was initiated and whether civil or criminal proceedings were instigated or pending. It is also recorded if there were no court proceedings. When available, information about the legal outcome and perpetrator details (e.g., whether the perpetrator has acknowledged or confessed to the injury, and their age and relationship to the child) were noted.
Surety of Diagnosis An accurate diagnosis of NAHI predicates the investigation of true incidence figures. Guidelines for the confident diagnosis of NAHI are still required from large-scale prospective studies of accidental and non-accidental injuries to enable highly significant predictions from history, examination, and investigative findings. At the present time, significantly predictive factors have been extracted from prospective studies in the existing literature. The categories of certainty/uncertainty— as suggested by Keenan3 in 2003: definite, probable/ presumptive, possible/not certain, and not non-accidental head injury— have been employed and only those cases designated definite/probable were counted for the purposes of this incidence calculation. Those cases designated definite include confessed/ acknowledged cases and those with combinations of clinical and investigative findings that have been found to be highly significantly predictive in prospective studies of unselected infant injuries of a diagnosis of non-accidental injury. For example, Goldstein et al.4 in 1994 reported that any two of the following: (1) inconsistent history/clinical exam; (2) retinal hemorrhage; or (3) parental risk factors (alcohol/ drug abuse, previous social service intervention, past history of child abuse/neglect), highly significantly (p⬍0.001) indicated inflicted injury. Other examples of different combinations of clinical, ophthalmologic, and radiologic syndrome elements of NAHI that similarly predict a definite diagnosis would include: hypoxic ischemic encephalopathy plus interhemispheric subdural hemorrhage (Rao et al.5,6); multiple compartment subdural hemorrhage (bilateral hemispheric, interhemispheric, suboccipital, subtemporal, posterior fossa, spinal); and a full complement of the syndrome features such as typical subdural hemorrhage features (bilateral convexity, interhemispheric, tears, ruptured bridging veins) together with multilayer retinal hemorrhages and retinoschisis, bruising, metaphyseal and rib fractures, with or without skull fracture, an acute encephalopathy, and seizures. Finally, evidence of malicious injury would fall into the definite category.
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The probable or presumptive criteria were well summarized by Duhaime et al.7 in her flow diagram. Cases with a subdural hemorrhage, retinal hemorrhages, and skeletal injuries, together with a short fall history without evidence of impact, would fall into this category.
Table 1. Population and incidence of “definite/probable” non-accidental head injuries (NAHI) for Lothian region, 1998 –2006
Validation of Data Acquisition Validation was done by emailing questionnaires to the participating centers on a monthly basis. A separate search of the Information and Statistics Division of the Scottish Health Service ICD-10 coding system also might be undertaken. A further search of the Registrar Database for Childhood Deaths in Scotland was an attempt to ensure inclusion of those children with “hyperacute”8 craniocervical injury who might be dead on arrival, or shortly after presentation to hospital, and therefore would not be included in returns from intensive care or other hospital wards. Verification of the numbers and patient information was attempted by liaison with lead clinicians in child protection in the various regions of Scotland. This was done by means of a regular non-accidental head injury interest group meeting with representatives from these regions who advise of cases occurring recently in their area.
Social Factors Social factors might be contributory to the diagnosis but not a fundamental part of the diagnostic process. This was exemplified by an analogy with the diagnosis of “failure to thrive,” where delayed growth parameters made the diagnosis, and, barring gross malnutrition, and after exclusion of system disease and simple metabolic/biochemical issues, maternal child interaction factors (social factors) were deemed to be etiologic. The use of the database to investigate risk factors for children suffering non-accidental head injury is helpful, but one cannot use risk factors to make the diagnosis and then utilize the database to investigate common risk factors. Some criteria (e.g., as cited above by Goldstein9) include parental risk factors for making the diagnosis. It is therefore important
Figure 2. Incidence of “Suspected NAHI” in Scotland per 100,000 children aged 0 –12 months, 1998 –2002. Using updated population data from GROS (General Register Office, Scotland).
Year
Population of Lothian
Number of cases (nⴝ25)
Lothian incidence NAHI per 100,000
1998 1999 2000 2001 2002 2003 2004 2005 2006
8837 8857 8537 8116 8143 8132 8533 8480 6380a
3 3 4 4 3 3 1 2 2
33.95 33.87 46.85 49.29 36.84 36.89 11.72 23.58 31.35
a
January–September.
to be clear about which criteria are to be used for “definite” and “probable” diagnoses. Risk factors for child abuse and neglect may emanate from (1) the child victim (prematurity, twin birth, difficult temperament, and delayed neurodevelopment)10; (2) the perpetrator profile and background (e.g., lack of prenatal care, victim of physical, domestic violence and substance abuse,11 depression or other mental illness, and single12 parent aged ⬍25 years) (unpublished data, Scottish database); (3) the wider community (social contributory factors, which include poverty, unemployment, and relatively low socioeconomic status13–17), and previous social work involvement with the family.4 Some cases, however, have none or few of the classic factors for concern. Many of these child victim, perpetrator, and community factors are overlapping, and there are relatively few prospective studies that have attempted to identify and rank their relative importance. This database has the ability to make use of the family postcode (like U.S. ZIP codes) to uniquely investigate social deprivation of the indexed cases. Traditional measures of estimating deprivation in the UK such as the census-based
Figure 3. Incidence figures and confidence intervals for Lothian region, for non-accidental head injury (NAHI) cases ⬍1 year. *See Discussion for text relating to population estimate.
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Carstairs Index are applied at the postcode level. There are 124 postcode areas in the UK and 17 within Scotland. An example is EH9 1LF, where “EH” indicates the postcode area; “9” indicates the postcode district (approximately 20 districts within an area); “1” indicates the sector (approximately 300 addresses per sector); and “LF” is a unit of approximately 15 addresses within the sector. Sectors have an average population size of approximately 5000 and have been correctly criticized in the past as an inappropriately large unit of geography with which to measure social deprivation, because there may be various pockets of deprivation/affluence that are not identifiable at that level. For this reason, the Scottish Executive developed a new geography, the “data zone” with an average population size of 750, and this is the unit on which the new SIMD has been developed. The SIMD identifies small area concentrations of multiple deprivation across all of Scotland in a fair way. It allows effective targeting of policies and funding where the aim is to wholly or partly tackle or take account of area
concentrations of multiple deprivation. (See www.scotland. gov.uk/library5/government/glsimd-00.asp.) To use this system, a patient’s postcode is mapped to one of the 6505 data zones across Scotland. The data zone ranked 1 (by the SIMD2004 and the updated SIMD2006) is most deprived, and the data zone ranked 6505 is the least deprived. The 2006 SIMD index brings together 37 indicators which offer specific aspects of deprivation, such as current income; employment; health; education, skills and training; geographic access; housing; and crime. These are combined to create the overall SIMD2006 index.
Results From a total of 160 cases in the database, some 56 were added prior to 1998. The prospective study was conducted from January 1, 1998 to September 30, 2006. There were 104 suspected NAHI cases during the study period.
Perth & Kinross
Fife
Clackmannanshire Clackmannanshire
Stirling
Falkirk
East Lothian City of Edinburgh City of Edinburgh
West Lothian North Lanarkshire
East Lothian
Midlothian
South Lanarkshire Scottish Borders
Midlothian
SIMD quintile key
20
NAHI cases
1–1301 15
1302–2602 2603–3903
10
3904–5204 5205–6505
5
0
1–1301
Most deprived
1302– 2602
2603– 3903
SIMD quintiles
3904– 5204
5205–6505
Least deprived
SIMD rank for 25 NAHI cases Median: 863 Range: 34–5869 SIMD rank for whole population of Lothian Median: 4009 Range: 4–6505
Figure 4. Overall Scottish Index of Multiple Deprivation (SIMD) mapping for Lothian region (West Lothian, Midlothian, East Lothian, and the City of Edinburgh) and detailed mapping of the City of Edinburgh showing color-coded quintiles from the most-deprived to the least-deprived for the combined domains of income, employment, health, housing, education, crime, and geographic access. Each non-accidental head injury (NAHI) case is located by a dot according to postcode. The bar chart shows similarly color-matched precise data zones (from 1 to 6505) in quintiles. The median SIMD rank for NAHI cases comparing the whole Lothian population is shown.
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Incidence of Suspected NAHI for Scotland, 1998 –2002
been retrospectively adjusted in the light of confirmed infant populations (by the General Register, Office for Scotland) for those years and the precise incidence ranges from 22 to 32 (Figure 2).
At this time, a number of cases throughout Scotland remain unconfirmed and cannot be designated as definite or probable because of insufficient or outstanding information. Although regional differences in
20
15
15
15
10
10
1–1301
Most deprived
1302– 2602
3904– 5204
2603– 3903
SIMD quintiles
0
5205–6505
Least deprived
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Most deprived
3904– 5204
2603– 3903
Education quintiles
1–1301
5205–6505
Most deprived
Least deprived
20
NAHI cases
20
15
10
1–1301
Most deprived
1302– 2602
2603– 3903
3904– 5204
Health quintiles
15
NB: No cases in 4th quintile
10
5205–6505
1–1301
Least deprived
Most deprived
1302– 2602
2603– 3903
3904– 5204
Housing quintiles
3904– 5204
Employment quintiles
5205–6505
Least deprived
15
10
5205–6505
1–1301
Least deprived
Most deprived
1302– 2602
2603– 3903
Income quintiles
3904– 5204
5205–6505
Least deprived
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15
NAHI cases
NAHI cases
2603– 3903
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0
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20
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NAHI cases
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NAHI cases
Incidence of Definite/Probable NAHI for the Lothian Region, 1998 –2006
20
NAHI cases
NAHI cases
Previously published incidence figures for “suspected NAHI” for the whole of Scotland2 for 1998 –2002 (inclusive) were 24.6 per 100,00 children ⬍1 year (95% CI⫽14.9 –38.5). Cases were found to be more common in urban regions and during the autumn and winter months. Brain injury cases occurred almost exclusively in young infants (median age⫽2.2 months) and the risk of the child suffering non-accidental head injury by the age of 1 year was 1 in 4065.19 The denominator has
1–1301
Most deprived
1302– 2602
2603– 3903
Crime quintiles
3904– 5204
5205–6505
Least deprived
1–1301
Most deprived
1302– 2602
2603– 3903
3904– 5204
Geographic quintiles
5205–6505
Least deprived
Figure 5. Histograms (with five quintiles, apart from Housing) for the combined Scottish Index of Multiple Deprivation (SIMD) and the subdomains of education and skills, employment, health, income, crime, and geographic access.
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Table 2. Criteria employed for study of incidence and confidence intervals for non-accidental head injuries (NAHI) Requirement
Specific details
Population based
All hospitals in a defined area admitting infants and children, including pediatric hospitals and accident and emergency department accepting children, pediatric wards, intensive care units admitting children, pediatric neurosurgical and neurologic units in general hospitals. Prospective study (statistical requisite). Definite/probable NAHI only included. Clear case definition. Verification of numbers. Verification of patient details, such as imaging. A geographic area and denominator population that can practically be verified (larger areas may underestimate full ascertainment of incidence while smaller areas may miss regional variation in frequency). Forensic records of early NAHI deaths. Committed regional pediatricians.
Design Accurate diagnosis Complete ascertainment
incidence will likely be minimized in any large study over a large population, ascertainment difficulties may be increased. Additionally, a relatively broad case definition may result in reported cases being not strictly comparable. Incidence and confidence intervals therefore have been calculated and graphed only for the Lothian Region (postcode prefixed by EH) where the acquisition of cases of “definite/probable” nonaccidental head injury is believed to be complete. Because small numbers of NAHI are assumed to be occurring randomly in a small population area, a Poisson confidence interval calculation has been used. The childhood population for the Lothian region for children aged ⬍1 year for the study is shown in Table 1 along with the corresponding incidence and numbers of definite and probable cases of NAHI. The mean incidence for this period was 33.8/100,000 infants per year (range⫽11.72– 49.29) (see Figure 3).
Social Status for All Lothian Region Cases of NAHI, 1998 –2006 The category of overall deprivation for the Lothian region cases (N⫽25) of NAHI based on postcode and SIMD, is shown in Figure 4. It can be seen that 64% of cases are located in the lowest quintile (i.e., mostdeprived category). The component subdomains of this overall SIMD category include income, in which 60% are represented in the lowest and most-deprived category. For the other domains, such as employment, 48% are in the most-deprived category and 68% in the lowest health quintile. Similarly, 76% are located in the lowest quintile of education, skills, and training, 52% for housing, and 72% for crime. Paradoxically, 76% of cases are located in the top 2 quintiles, that is, the least-deprived, for geographic access, which is composed of indicators that reflect the transport time to places such as a general medical practice, shopping facilities, post office, or secondary school (Figure 5). April 2008
Discussion This population-based prospective study with clear case definitions fulfills the essential requirements (Table 2) for calculating the true incidence and confidence intervals of NAHI in a defined region, southeast Scotland. Potential limitations to the NAHI incidence calculation in this study are relatively minor but always remain a possibility. First, the accuracy of “surety of diagnosis” (i.e., definite or probable) was paramount. Particular attention was paid to excluding possible NAHI diagnoses or other cases of SDH deemed not to be of non-accidental origin. Second, ascertainment from all areas is essential and any reluctance to diagnose or report cases from particular regions might result in an underestimate of the true incidence. The nature of the region’s geography and medical referral pattern to the specialist tertiary hospital for all serious children’s head injury cases (including NAHI) reassured us of virtual total ascertainment of all cases. Third, a potential minor error is the normal infant population figure, which is based on government midyear estimates retrospectively and the incidence from January to September 2006 was based on the proportion of the normal population (75%) at the time of analysis. Fourth, if cases of NAHI were presenting to different tertiary hospitals, the case definition could conceivably be insufficiently precise to recruit all of the varied presentations of NAHI. However, with referral to a single tertiary hospital this does not apply. Fifth, should the diagnosis change from non-accidental to accidental head injury without alteration on the database a counting error would occur. Sixth, similarly, if a later court decision found to the contrary, it may not have been withdrawn from the calculation of the incidence. Seventh, errors in data handling such as transferring complex data onto the database will occasionally lead to inaccurate information being logged, and some information may be from restricted files or difficult to access (e.g., legal, social work, police, or community health records). Finally, maintenance of this database Am J Prev Med 2008;34(4S)
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Table 3. Published incidence figures from the UK Study
Journal
Study type
Study duration
Group
Average incidence
Barlow (1998)
Scott Med J
Retros
15 years
Suspected NAHI
Jayawant (1998)19
BMJ
Retros
3 years
SDH
Barlow (2000)20
Lancet
Prosp
18 months
Suspected NAHI
Hobbs (2005)9
Arch Dis Child
Prosp
1 year
Non-accidental (SDH/SDE)
0.04/1000/yr for children aged ⬍5 yrs 10.3/100,000/yr for children aged ⬍1 yr 24.6/100,000/yr for children aged ⬍1 yr 14.2/100,000/yr for children aged ⬍1 yr
18
NAHI, non-accidental head injury; Prosp, prospective study; Retros, retrospective study; SDE, subdural effusion; SDH, subdural hematoma.
relied on a part-time data manager and the goodwill of child-protection pediatricians and was not a timelimited grant funded study.
Incidence Studies Studies published from the UK are shown in Table 3. Two UK epidemiologic studies9,19 suggest an incidence of non-accidental head injury for infants with a subdural hematoma to be approximately 10 –14 per 100,000 infants per year. Earlier figures for suspected NAHI for the whole of Scotland were 24.6 per 100,000, and current figures for a verifiable region with essentially complete ascertainment have shown a mean incidence of NAHI of 33.8 per 100,000 infants per year. This is considered to be an accurate reflection of the incidence in this region, where it is likely all cases were identified and none omitted. There is no reason to suspect that this high incidence figure in an area of relative affluence in the country would be expected to be unusually higher than in other comparable regions or cities in the UK and possibly highlights shortcomings implicit in larger population-area studies where incomplete ascertainment and underreporting might occur in areas where there is a reticence in accepting a diagnosis of non-accidental head injury under any circumstances.
Social Profile of Perpetrators Apart from calculating the incidence rates and trends of NAHI in Scotland, the Scottish database can be utilized additionally for the study of the changing nature of injuries (which might occur as a result of any intervention program) and to report the global outcome of confirmed cases of NAHI. It should prove useful in reporting the frequency of the syndrome elements and in defining an expanded syndrome of NAHI in infants. One particularly useful facet is the facility to study contributory social factors as they occur in family/ caregiver dynamics and can help define the risk factors for infantile NAHI. Exposure of the social setting is possible by utilizing the patient’s postcode at acute hospital admission and the new Scottish Index of Multiple Deprivation.
In different parts of the world the profile of the shaker/perpetrator may be different. For example, child caregivers or nannies of a middle-class background, immigrant nannies from other cultures or, as found in this study, perpetrators who almost invariably derive from the lower socioeconomic groups. In the overall Index of Multiple Deprivation, 64% were located in the lowest quintile, and only 16% of cases (4/25) were distributed in the top three quintiles. A similar profile was evident for all subdomains, particularly for education, skills, and training in which 76% were in the lowest quintile with only six of 25 cases distributed across the upper four quintiles. In employment, 84% belonged to the lowest two quintiles. A similar picture is seen for health, income, housing, and crime (Figure 5). The geographic access subdomain (which provides an index of accessibility to common destinations such as primary medical care sites, secondary schools, shopping, and postal services) is almost totally reversed from the other profile descriptors showing that accessibility to these important services is not a factor in the perpetrator families. This reflects positively on existing government social policy. It appears the perpetrators in this series fit a strongly skewed profile, aggregating to the lowest socioeconomic groups, with little middle-class representation, and reflecting a locally distinctive social profile of perpetrators in this region of Scotland. We are grateful to the Lloyds TSB Foundation for Scotland for support for non-accidental head injury research in the University of Edinburgh. We would like to acknowledge the contribution made by Eleanor Kerr, Gillian Lawson, Caroline Millar, and Karen Barlow over the period of the study. Particular thanks go to Stuart Macdonald of EDINA National Data Centre and Edinburgh University Data Library, and Robin Rice, Data Librarian, EDINA and University Data Library, University of Edinburgh, Scotland, UK. No financial disclosures were reported by the authors of this paper.
References 1. Minns RA, Brown JK. Neurological perspectives of non-accidental head injury and whiplash/shaken baby syndrome: An overview. In: Minns RA,
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2.
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4. 5. 6. 7.
8. 9. 10.
Brown JK, eds. Shaking and other non-accidental head injuries in children. London: Mac Keith Press, 2005:1–105. Minns RA, Millar C, Minns FC, Lo T, Jones PA, Barlow KM. Non-accidental head injury in Scotland: the Scottish database. In: Minns RA, Brown JK, eds. Shaking and other non-accidental head injuries in children. London: Mac Keith Press, 2005:154 – 84. Keenan H. Nomenclature, definitions, incidence and demographics of inflicted childhood neurotrauma. In: Reece RM, Nicholson CE, eds. Inflicted childhood neurotrauma. Elk Grove Village IL: American Academy of Pediatrics, 2003:3–11. Goldstein B, Kelly MM, Bruton D, Cox C. Inflicted versus accidental head injury in critically injured children. Crit Care Med 1993;21:1328 –32. Rao P, Carty H, Pierce A. The acute reversal sign: Comparison of medical and non- accidental injury patients. Clin Radiol 1999;54:495–501. Rao P, Carty H. Non-accidental injury: Review of the radiology. Clin Radiol 1999;54:11–24. Duhaime AC, Alario AJ, Lewander WJ, et al. Head injury in very young children: mechanisms, injury types, and ophthalmologic findings in 100 hospitalized patients younger than 2 years of age. Pediatrics 1992;90: 179 – 85. Minns RA, Busuttil A. Patterns of presentation of the shaken baby syndrome: Four types of inflicted brain injury predominate. BMJ 2004;328:766. Hobbs C, Childs AM, Wynne J, Livingston J, Seal A. Subdural haematoma and effusion in infancy. An epidemiological study. Arch Dis Child 2005;90:952–5. Mok JY-Q. Child protection and the prevention of abuse. In: Minns RA, Brown JK, eds. Shaking and other non-accidental head injuries in children. London: Mac Keith Press, 2005:415–26.
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11. Kaplun D, Reich R. The murdered child and his killers. Am J Psychiatry 1976;133:809 –13. 12. Wu SS, Ma CX, Carter RL, et al. Risk factors for infant maltreatment: a population-based study. Child Abuse Neglect 2004;28:1253– 64. 13. American Medical Association Council on Scientific Affairs. AMA diagnostic and treatment guidelines concerning child abuse and neglect. JAMA 1985;254:796 – 800. 14. Hunter RS, Kilstrom N, Kraybill EN, Loda F. Antecedents of child abuse and neglect in premature infants: a prospective study in a newborn intensive care unit. Pediatrics 1978;61:629 –35. 15. Nagler J. Child abuse and neglect. Curr Opin Pediatr 2002;14:251– 4. 16. Overpeck MD, Brenner RA, Trumble AC, Trifiletti LB, Berendes HW. Risk factors for infant homicide in the United States. N Engl J Med 1998;339: 1211– 6. 17. Sedlak A, Broadhurst DD. Executive summary of the third National Incidence Study of Child Abuse and Neglect. Washington DC: U.S. Department of Health and Human Services Administration for Children and Families. Administration on Children, Youth and Families. National Center on Child Abuse and Neglect, 1996. 18. Barlow KM, Milne S, Aitken K, Minns RA. A retrospective epidemiological analysis of non-accidental head injury in children in Scotland over a 15 year period. Scott Med J 1998;43:112– 4. 19. Jayawant S, Rawlinson A, Gibbon F, et al. Subdural haemorrhages in infants: Population based study. BMJ 1998;317:1558 – 61. 20. Barlow KM, Minns RA. Annual incidence of shaken impact syndrome in young children. Lancet 2000;356:1571–2.
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This prospective population-based study was conducted from January 1998 to September 2006. Data from the Lothian region of Scotland, where there is known full ascertainment of infant head injuries, including NAHI, have been used to calculate the incidence rate for this region of Scotland, with government statistics providing the normal annual infant population as the denominator. A new Scottish Index of Multiple Deprivation (SIMD), which assesses a very focused area (data zone population size⫽750) and provides novel information about social demography for education, housing, employment, health, crime, income, and geographic accessibility to services, was applied to the identified cases of NAHI during this study period.
Results:
The mean incidence of NAHI in southeast Scotland for 8.75 years was 33.8/100,000 infants per year. The cases of NAHI were mostly located in the lowest 1 (or 2) quintiles for all SIMD domains (education, housing, employment, health, crime, income), although they had good accessibility to medical and other community services.
Conclusions: The incidence rates from this prospective study for NAHI are considerably higher than other published UK surveys and are not considered to reflect a cluster effect. The perpetrators in this study fit a strongly skewed profile aggregating to the lowest socioeconomic groups in the community. (Am J Prev Med 2008;34(4S):S126 –S133) © 2008 American Journal of Preventive Medicine
Introduction
B
rain injury results from less than 1% of all types of child abuse and occurs in 1.8% of all cases of physical abuse.1 Although only a small segment of the whole panoply of child abuse, non-accidental head injury (NAHI; also called inflicted traumatic brain injury [inflicted TBI] and shaken baby syndrome [SBS]) accounts for an overwhelming number of fatal or life-threatening injuries attributed to physical abuse of children aged ⬍1 year. Some 20% of NAHI are fatal, while serious sequelae of learning disabilities, motor disabilities, blindness, epilepsy, or organic behavioral problems occur in approximately 60% of those who survive.1,2
From the Department of Child Life and Health, University of Edinburgh (Minns, Jones, Mok); Royal Hospital for Sick Children, Lothian University Hospitals NHS Trust (Minns, Mok), Edinburgh, Scotland, United Kingdom Address correspondence and reprint requests to: Professor R.A. Minns, PhD, Department of Child Life and Health, Reproductive and Developmental Sciences, 20 Sylvan Place, Edinburgh EH9 1UW, UK. E-mail: [email protected].
The cost can be substantial to the child, his immediate and extended family, the pediatric services involved in his acute and chronic medical care, and expenses for civil and criminal proceedings. However, the real magnitude of the burden of NAHI for any population can be appreciated only by multiplying the overall financial and emotional costs for the individual case by the true incidence. The incidence figure is important in planning for resources to address these issues and to fund surveillance by child-protection teams, including health visitors, social workers, district nurses, general practitioners, and pediatricians. Few studies have examined the incidence of NAHI and addressed the social demography of those cases in the population. The true incidence is important to assess effectiveness of new research proposals or public health strategies in a scientific way. The most accurate incidence figures likely will be derived from prospective population studies, which require the number of infants in the population annually as a denominator. The social demography of the families of children in the population with NAHI will further focus prevention
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strategies to ensure that the intervention is targeting those families in the population at a high risk of NAHI. A prospective study was conducted to: (1) ascertain the precise incidence of NAHI in southeast Scotland; (2) compare these figures with figures obtained variously for other regions and parts of the country, including Scotland as a whole, England, and Wales; and (3) profile the cohort of infants with NAHI using a social demographic tool (the Scottish Index of Multiple Deprivation [SIMD]).
Patients and Methods Participating Centers A prospective study (active surveillance) was commenced in 1998 to assess the incidence and demography of NAHI in Scotland. All Scottish pediatric and general hospitals with pediatric wards, Accident and Emergency departments admitting children, neurosurgical/neurologic units, and intensive care units admitting children were consulted on a regular basis (monthly) by a data coordinator requesting details concerning any recently admitted infants with a provisional diagnosis of “suspected non-accidental head injury.” Patient details were transferred onto an SPSS database. For the collection of demographic and patient details, names and addresses were required but not included in the database. The study has both Local and Multicentre Research Ethics approval. There are 16 hospitals in Scotland with pediatric units (midyear 2005 population equals approximately 5,094,800) transferring information to this database.2 The General Register Office for Scotland provides government statistics (www. GRO–Scotland.gov.uk/). This website provides midyear population estimates for Scotland by gender, every age (by year), and administrative and Health Board areas. This provides the denominator for the incidence calculations. The total infant population (i.e., children aged ⬍1 year) at mid-2005 was 54,476. Figure 1 shows the infant population nationally and for the Edinburgh and surrounding area (Lothian region).
Case Definition Local investigators were required to complete a form for any child presenting with “suspected NAHI,” and specifically for
Figure 1. The infant population nationally and for Edinburgh and the surrounding area (Lothian region).
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any child with evidence of a subdural hemorrhage or retinal hemorrhage, alone or in combination.
Data Collection The form for data collection consisted of 153 items in 11 sections: (1) demography including postcode; (2) history (medical diagnostic background); (3) presenting symptoms; (4) presenting signs; (5) imaging (cranial and peripheral); (6) retinal findings; (7) other injuries (fractures, bruising, signs of contact); (8) severity of injury (measured intracranial pressure levels, duration of ventilation); (9) outcome (at hospital discharge and 6 months); (10) discharge diagnosis; and (11) degree of surety of diagnosis. The database notes whether a case conference for child protection was initiated and whether civil or criminal proceedings were instigated or pending. It is also recorded if there were no court proceedings. When available, information about the legal outcome and perpetrator details (e.g., whether the perpetrator has acknowledged or confessed to the injury, and their age and relationship to the child) were noted.
Surety of Diagnosis An accurate diagnosis of NAHI predicates the investigation of true incidence figures. Guidelines for the confident diagnosis of NAHI are still required from large-scale prospective studies of accidental and non-accidental injuries to enable highly significant predictions from history, examination, and investigative findings. At the present time, significantly predictive factors have been extracted from prospective studies in the existing literature. The categories of certainty/uncertainty— as suggested by Keenan3 in 2003: definite, probable/ presumptive, possible/not certain, and not non-accidental head injury— have been employed and only those cases designated definite/probable were counted for the purposes of this incidence calculation. Those cases designated definite include confessed/ acknowledged cases and those with combinations of clinical and investigative findings that have been found to be highly significantly predictive in prospective studies of unselected infant injuries of a diagnosis of non-accidental injury. For example, Goldstein et al.4 in 1994 reported that any two of the following: (1) inconsistent history/clinical exam; (2) retinal hemorrhage; or (3) parental risk factors (alcohol/ drug abuse, previous social service intervention, past history of child abuse/neglect), highly significantly (p⬍0.001) indicated inflicted injury. Other examples of different combinations of clinical, ophthalmologic, and radiologic syndrome elements of NAHI that similarly predict a definite diagnosis would include: hypoxic ischemic encephalopathy plus interhemispheric subdural hemorrhage (Rao et al.5,6); multiple compartment subdural hemorrhage (bilateral hemispheric, interhemispheric, suboccipital, subtemporal, posterior fossa, spinal); and a full complement of the syndrome features such as typical subdural hemorrhage features (bilateral convexity, interhemispheric, tears, ruptured bridging veins) together with multilayer retinal hemorrhages and retinoschisis, bruising, metaphyseal and rib fractures, with or without skull fracture, an acute encephalopathy, and seizures. Finally, evidence of malicious injury would fall into the definite category.
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The probable or presumptive criteria were well summarized by Duhaime et al.7 in her flow diagram. Cases with a subdural hemorrhage, retinal hemorrhages, and skeletal injuries, together with a short fall history without evidence of impact, would fall into this category.
Table 1. Population and incidence of “definite/probable” non-accidental head injuries (NAHI) for Lothian region, 1998 –2006
Validation of Data Acquisition Validation was done by emailing questionnaires to the participating centers on a monthly basis. A separate search of the Information and Statistics Division of the Scottish Health Service ICD-10 coding system also might be undertaken. A further search of the Registrar Database for Childhood Deaths in Scotland was an attempt to ensure inclusion of those children with “hyperacute”8 craniocervical injury who might be dead on arrival, or shortly after presentation to hospital, and therefore would not be included in returns from intensive care or other hospital wards. Verification of the numbers and patient information was attempted by liaison with lead clinicians in child protection in the various regions of Scotland. This was done by means of a regular non-accidental head injury interest group meeting with representatives from these regions who advise of cases occurring recently in their area.
Social Factors Social factors might be contributory to the diagnosis but not a fundamental part of the diagnostic process. This was exemplified by an analogy with the diagnosis of “failure to thrive,” where delayed growth parameters made the diagnosis, and, barring gross malnutrition, and after exclusion of system disease and simple metabolic/biochemical issues, maternal child interaction factors (social factors) were deemed to be etiologic. The use of the database to investigate risk factors for children suffering non-accidental head injury is helpful, but one cannot use risk factors to make the diagnosis and then utilize the database to investigate common risk factors. Some criteria (e.g., as cited above by Goldstein9) include parental risk factors for making the diagnosis. It is therefore important
Figure 2. Incidence of “Suspected NAHI” in Scotland per 100,000 children aged 0 –12 months, 1998 –2002. Using updated population data from GROS (General Register Office, Scotland).
Year
Population of Lothian
Number of cases (nⴝ25)
Lothian incidence NAHI per 100,000
1998 1999 2000 2001 2002 2003 2004 2005 2006
8837 8857 8537 8116 8143 8132 8533 8480 6380a
3 3 4 4 3 3 1 2 2
33.95 33.87 46.85 49.29 36.84 36.89 11.72 23.58 31.35
a
January–September.
to be clear about which criteria are to be used for “definite” and “probable” diagnoses. Risk factors for child abuse and neglect may emanate from (1) the child victim (prematurity, twin birth, difficult temperament, and delayed neurodevelopment)10; (2) the perpetrator profile and background (e.g., lack of prenatal care, victim of physical, domestic violence and substance abuse,11 depression or other mental illness, and single12 parent aged ⬍25 years) (unpublished data, Scottish database); (3) the wider community (social contributory factors, which include poverty, unemployment, and relatively low socioeconomic status13–17), and previous social work involvement with the family.4 Some cases, however, have none or few of the classic factors for concern. Many of these child victim, perpetrator, and community factors are overlapping, and there are relatively few prospective studies that have attempted to identify and rank their relative importance. This database has the ability to make use of the family postcode (like U.S. ZIP codes) to uniquely investigate social deprivation of the indexed cases. Traditional measures of estimating deprivation in the UK such as the census-based
Figure 3. Incidence figures and confidence intervals for Lothian region, for non-accidental head injury (NAHI) cases ⬍1 year. *See Discussion for text relating to population estimate.
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Carstairs Index are applied at the postcode level. There are 124 postcode areas in the UK and 17 within Scotland. An example is EH9 1LF, where “EH” indicates the postcode area; “9” indicates the postcode district (approximately 20 districts within an area); “1” indicates the sector (approximately 300 addresses per sector); and “LF” is a unit of approximately 15 addresses within the sector. Sectors have an average population size of approximately 5000 and have been correctly criticized in the past as an inappropriately large unit of geography with which to measure social deprivation, because there may be various pockets of deprivation/affluence that are not identifiable at that level. For this reason, the Scottish Executive developed a new geography, the “data zone” with an average population size of 750, and this is the unit on which the new SIMD has been developed. The SIMD identifies small area concentrations of multiple deprivation across all of Scotland in a fair way. It allows effective targeting of policies and funding where the aim is to wholly or partly tackle or take account of area
concentrations of multiple deprivation. (See www.scotland. gov.uk/library5/government/glsimd-00.asp.) To use this system, a patient’s postcode is mapped to one of the 6505 data zones across Scotland. The data zone ranked 1 (by the SIMD2004 and the updated SIMD2006) is most deprived, and the data zone ranked 6505 is the least deprived. The 2006 SIMD index brings together 37 indicators which offer specific aspects of deprivation, such as current income; employment; health; education, skills and training; geographic access; housing; and crime. These are combined to create the overall SIMD2006 index.
Results From a total of 160 cases in the database, some 56 were added prior to 1998. The prospective study was conducted from January 1, 1998 to September 30, 2006. There were 104 suspected NAHI cases during the study period.
Perth & Kinross
Fife
Clackmannanshire Clackmannanshire
Stirling
Falkirk
East Lothian City of Edinburgh City of Edinburgh
West Lothian North Lanarkshire
East Lothian
Midlothian
South Lanarkshire Scottish Borders
Midlothian
SIMD quintile key
20
NAHI cases
1–1301 15
1302–2602 2603–3903
10
3904–5204 5205–6505
5
0
1–1301
Most deprived
1302– 2602
2603– 3903
SIMD quintiles
3904– 5204
5205–6505
Least deprived
SIMD rank for 25 NAHI cases Median: 863 Range: 34–5869 SIMD rank for whole population of Lothian Median: 4009 Range: 4–6505
Figure 4. Overall Scottish Index of Multiple Deprivation (SIMD) mapping for Lothian region (West Lothian, Midlothian, East Lothian, and the City of Edinburgh) and detailed mapping of the City of Edinburgh showing color-coded quintiles from the most-deprived to the least-deprived for the combined domains of income, employment, health, housing, education, crime, and geographic access. Each non-accidental head injury (NAHI) case is located by a dot according to postcode. The bar chart shows similarly color-matched precise data zones (from 1 to 6505) in quintiles. The median SIMD rank for NAHI cases comparing the whole Lothian population is shown.
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Incidence of Suspected NAHI for Scotland, 1998 –2002
been retrospectively adjusted in the light of confirmed infant populations (by the General Register, Office for Scotland) for those years and the precise incidence ranges from 22 to 32 (Figure 2).
At this time, a number of cases throughout Scotland remain unconfirmed and cannot be designated as definite or probable because of insufficient or outstanding information. Although regional differences in
20
15
15
15
10
10
1–1301
Most deprived
1302– 2602
3904– 5204
2603– 3903
SIMD quintiles
0
5205–6505
Least deprived
1–1301
1302– 2602
Most deprived
3904– 5204
2603– 3903
Education quintiles
1–1301
5205–6505
Most deprived
Least deprived
20
NAHI cases
20
15
10
1–1301
Most deprived
1302– 2602
2603– 3903
3904– 5204
Health quintiles
15
NB: No cases in 4th quintile
10
5205–6505
1–1301
Least deprived
Most deprived
1302– 2602
2603– 3903
3904– 5204
Housing quintiles
3904– 5204
Employment quintiles
5205–6505
Least deprived
15
10
5205–6505
1–1301
Least deprived
Most deprived
1302– 2602
2603– 3903
Income quintiles
3904– 5204
5205–6505
Least deprived
20
15
NAHI cases
NAHI cases
2603– 3903
5
20
10
15
10
5
5
0
1302– 2602
20
5
5
10
5
5
NAHI cases
0
NAHI cases
20
5
NAHI cases
Incidence of Definite/Probable NAHI for the Lothian Region, 1998 –2006
20
NAHI cases
NAHI cases
Previously published incidence figures for “suspected NAHI” for the whole of Scotland2 for 1998 –2002 (inclusive) were 24.6 per 100,00 children ⬍1 year (95% CI⫽14.9 –38.5). Cases were found to be more common in urban regions and during the autumn and winter months. Brain injury cases occurred almost exclusively in young infants (median age⫽2.2 months) and the risk of the child suffering non-accidental head injury by the age of 1 year was 1 in 4065.19 The denominator has
1–1301
Most deprived
1302– 2602
2603– 3903
Crime quintiles
3904– 5204
5205–6505
Least deprived
1–1301
Most deprived
1302– 2602
2603– 3903
3904– 5204
Geographic quintiles
5205–6505
Least deprived
Figure 5. Histograms (with five quintiles, apart from Housing) for the combined Scottish Index of Multiple Deprivation (SIMD) and the subdomains of education and skills, employment, health, income, crime, and geographic access.
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Table 2. Criteria employed for study of incidence and confidence intervals for non-accidental head injuries (NAHI) Requirement
Specific details
Population based
All hospitals in a defined area admitting infants and children, including pediatric hospitals and accident and emergency department accepting children, pediatric wards, intensive care units admitting children, pediatric neurosurgical and neurologic units in general hospitals. Prospective study (statistical requisite). Definite/probable NAHI only included. Clear case definition. Verification of numbers. Verification of patient details, such as imaging. A geographic area and denominator population that can practically be verified (larger areas may underestimate full ascertainment of incidence while smaller areas may miss regional variation in frequency). Forensic records of early NAHI deaths. Committed regional pediatricians.
Design Accurate diagnosis Complete ascertainment
incidence will likely be minimized in any large study over a large population, ascertainment difficulties may be increased. Additionally, a relatively broad case definition may result in reported cases being not strictly comparable. Incidence and confidence intervals therefore have been calculated and graphed only for the Lothian Region (postcode prefixed by EH) where the acquisition of cases of “definite/probable” nonaccidental head injury is believed to be complete. Because small numbers of NAHI are assumed to be occurring randomly in a small population area, a Poisson confidence interval calculation has been used. The childhood population for the Lothian region for children aged ⬍1 year for the study is shown in Table 1 along with the corresponding incidence and numbers of definite and probable cases of NAHI. The mean incidence for this period was 33.8/100,000 infants per year (range⫽11.72– 49.29) (see Figure 3).
Social Status for All Lothian Region Cases of NAHI, 1998 –2006 The category of overall deprivation for the Lothian region cases (N⫽25) of NAHI based on postcode and SIMD, is shown in Figure 4. It can be seen that 64% of cases are located in the lowest quintile (i.e., mostdeprived category). The component subdomains of this overall SIMD category include income, in which 60% are represented in the lowest and most-deprived category. For the other domains, such as employment, 48% are in the most-deprived category and 68% in the lowest health quintile. Similarly, 76% are located in the lowest quintile of education, skills, and training, 52% for housing, and 72% for crime. Paradoxically, 76% of cases are located in the top 2 quintiles, that is, the least-deprived, for geographic access, which is composed of indicators that reflect the transport time to places such as a general medical practice, shopping facilities, post office, or secondary school (Figure 5). April 2008
Discussion This population-based prospective study with clear case definitions fulfills the essential requirements (Table 2) for calculating the true incidence and confidence intervals of NAHI in a defined region, southeast Scotland. Potential limitations to the NAHI incidence calculation in this study are relatively minor but always remain a possibility. First, the accuracy of “surety of diagnosis” (i.e., definite or probable) was paramount. Particular attention was paid to excluding possible NAHI diagnoses or other cases of SDH deemed not to be of non-accidental origin. Second, ascertainment from all areas is essential and any reluctance to diagnose or report cases from particular regions might result in an underestimate of the true incidence. The nature of the region’s geography and medical referral pattern to the specialist tertiary hospital for all serious children’s head injury cases (including NAHI) reassured us of virtual total ascertainment of all cases. Third, a potential minor error is the normal infant population figure, which is based on government midyear estimates retrospectively and the incidence from January to September 2006 was based on the proportion of the normal population (75%) at the time of analysis. Fourth, if cases of NAHI were presenting to different tertiary hospitals, the case definition could conceivably be insufficiently precise to recruit all of the varied presentations of NAHI. However, with referral to a single tertiary hospital this does not apply. Fifth, should the diagnosis change from non-accidental to accidental head injury without alteration on the database a counting error would occur. Sixth, similarly, if a later court decision found to the contrary, it may not have been withdrawn from the calculation of the incidence. Seventh, errors in data handling such as transferring complex data onto the database will occasionally lead to inaccurate information being logged, and some information may be from restricted files or difficult to access (e.g., legal, social work, police, or community health records). Finally, maintenance of this database Am J Prev Med 2008;34(4S)
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Table 3. Published incidence figures from the UK Study
Journal
Study type
Study duration
Group
Average incidence
Barlow (1998)
Scott Med J
Retros
15 years
Suspected NAHI
Jayawant (1998)19
BMJ
Retros
3 years
SDH
Barlow (2000)20
Lancet
Prosp
18 months
Suspected NAHI
Hobbs (2005)9
Arch Dis Child
Prosp
1 year
Non-accidental (SDH/SDE)
0.04/1000/yr for children aged ⬍5 yrs 10.3/100,000/yr for children aged ⬍1 yr 24.6/100,000/yr for children aged ⬍1 yr 14.2/100,000/yr for children aged ⬍1 yr
18
NAHI, non-accidental head injury; Prosp, prospective study; Retros, retrospective study; SDE, subdural effusion; SDH, subdural hematoma.
relied on a part-time data manager and the goodwill of child-protection pediatricians and was not a timelimited grant funded study.
Incidence Studies Studies published from the UK are shown in Table 3. Two UK epidemiologic studies9,19 suggest an incidence of non-accidental head injury for infants with a subdural hematoma to be approximately 10 –14 per 100,000 infants per year. Earlier figures for suspected NAHI for the whole of Scotland were 24.6 per 100,000, and current figures for a verifiable region with essentially complete ascertainment have shown a mean incidence of NAHI of 33.8 per 100,000 infants per year. This is considered to be an accurate reflection of the incidence in this region, where it is likely all cases were identified and none omitted. There is no reason to suspect that this high incidence figure in an area of relative affluence in the country would be expected to be unusually higher than in other comparable regions or cities in the UK and possibly highlights shortcomings implicit in larger population-area studies where incomplete ascertainment and underreporting might occur in areas where there is a reticence in accepting a diagnosis of non-accidental head injury under any circumstances.
Social Profile of Perpetrators Apart from calculating the incidence rates and trends of NAHI in Scotland, the Scottish database can be utilized additionally for the study of the changing nature of injuries (which might occur as a result of any intervention program) and to report the global outcome of confirmed cases of NAHI. It should prove useful in reporting the frequency of the syndrome elements and in defining an expanded syndrome of NAHI in infants. One particularly useful facet is the facility to study contributory social factors as they occur in family/ caregiver dynamics and can help define the risk factors for infantile NAHI. Exposure of the social setting is possible by utilizing the patient’s postcode at acute hospital admission and the new Scottish Index of Multiple Deprivation.
In different parts of the world the profile of the shaker/perpetrator may be different. For example, child caregivers or nannies of a middle-class background, immigrant nannies from other cultures or, as found in this study, perpetrators who almost invariably derive from the lower socioeconomic groups. In the overall Index of Multiple Deprivation, 64% were located in the lowest quintile, and only 16% of cases (4/25) were distributed in the top three quintiles. A similar profile was evident for all subdomains, particularly for education, skills, and training in which 76% were in the lowest quintile with only six of 25 cases distributed across the upper four quintiles. In employment, 84% belonged to the lowest two quintiles. A similar picture is seen for health, income, housing, and crime (Figure 5). The geographic access subdomain (which provides an index of accessibility to common destinations such as primary medical care sites, secondary schools, shopping, and postal services) is almost totally reversed from the other profile descriptors showing that accessibility to these important services is not a factor in the perpetrator families. This reflects positively on existing government social policy. It appears the perpetrators in this series fit a strongly skewed profile, aggregating to the lowest socioeconomic groups, with little middle-class representation, and reflecting a locally distinctive social profile of perpetrators in this region of Scotland. We are grateful to the Lloyds TSB Foundation for Scotland for support for non-accidental head injury research in the University of Edinburgh. We would like to acknowledge the contribution made by Eleanor Kerr, Gillian Lawson, Caroline Millar, and Karen Barlow over the period of the study. Particular thanks go to Stuart Macdonald of EDINA National Data Centre and Edinburgh University Data Library, and Robin Rice, Data Librarian, EDINA and University Data Library, University of Edinburgh, Scotland, UK. No financial disclosures were reported by the authors of this paper.
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