A prevalence-based approach to societal costs occurring in consequence of child abuse and neglect
© Habetha et al.; licensee BioMed Central Ltd. 2012
Received: 15 May 2012
Accepted: 8 November 2012
Published: 16 November 2012
Traumatization in childhood can result in lifelong health impairment and may have a negative impact on other areas of life such as education, social contacts and employment as well. Despite the frequent occurrence of traumatization, which is reflected in a 14.5 percent prevalence rate of severe child abuse and neglect, the economic burden of the consequences is hardly known. The objective of this prevalence-based cost-of-illness study is to show how impairment of the individual is reflected in economic trauma follow-up costs borne by society as a whole in Germany and to compare the results with other countries’ costs.
From a societal perspective trauma follow-up costs were estimated using a bottom-up approach. The literature-based prevalence rate includes emotional, physical and sexual abuse as well as physical and emotional neglect in Germany. Costs are derived from individual case scenarios of child endangerment presented in a German cost-benefit-analysis. A comparison with trauma follow-up costs in Australia, Canada and the USA is based on purchasing power parity.
The annual trauma follow-up costs total to a margin of EUR 11.1 billion for the lower bound and to EUR 29.8 billion for the upper bound. This equals EUR 134.84 and EUR 363.58, respectively, per capita for the German population. These results conform to the ones obtained from cost studies conducted in Australia (lower bound) and Canada (upper bound), whereas the result for the United States is much lower.
Child abuse and neglect result in trauma follow-up costs of economically relevant magnitude for the German society. Although the result is well in line with other countries’ costs, the general lack of data should be fought in order to enable more detailed future studies. Creating a reliable cost data basis in the first place can pave the way for long-term cost savings.
KeywordsTrauma follow-up costs Trauma-related disorder Cost of illness Societal costs Childhood traumatization Child abuse Child neglect Child maltreatment
Traumatization of children (the United Nations Convention on the Rights of the Child defines a "child" as "a human being below the age of 18 years") occurs in many ways. Due to their often very pronounced aftereffects, sexual, physical and emotional abuse in the home environment play a central role. For example, Maercker et al.  describe a Post-Traumatic Stress Disorder after sexualized violence in more than one third of the cases and Steil and Straube  in up to 80% of the cases. Close relationship with the offender, repetitions and combinations of various forms of abuse significantly contribute to this strong impact on the individual [3–6].
All in all, childhood traumatization is not a rare event. In two German studies on juveniles and young adults, 25.5% of the male and 17.7% of the female participants , or a total of 22.5% of the investigated juveniles  had already experienced at least one traumatic event. The most common types of traumatic events were violent attacks, accidents and witnessing trauma. Child neglect – mostly subdivided into physical and emotional neglect – also belongs to the most common types of traumatization [4, 9, 10].
A recent representative population survey in Germany  has shown that emotional abuse concerned 14.9%, physical abuse 12.0% and sexual abuse 12.5% of the respondents, where 14.5% were affected by “severe/extreme” abuse or neglect, respectively. In a somewhat older investigation by Wetzels , 38.8% of the participants had experienced physical violence by the parents more often than rarely, while 4.7% were severely affected. Contact sexual abuse before the age of 18 was indicated by 6.5% of the respondents (3.2% of men and 9.6% of women). A share of 8.9% of the participants had witnessed violence between the parents more than rarely.
A characteristic feature of childhood traumatization is that children are often affected by several types of traumatization. This has been shown for Germany [6, 10] and in large population studies for Canada  and the USA [12, 13]. The rate of children who were affected by at least two types of traumatization is presented with 40% in a German study  and with one quarter in a US-American study .
Consequences of childhood traumatization
The consequences of childhood traumatization (hereinafter referred to as trauma-related disorders) are – apart from acute injuries and reactions – additionally mirrored in restricted social, emotional and physical development, which are associated with an increased risk of mental disorders, alcohol- and drug abuse as well as physical diseases in adulthood . The “Final Report of the Independent Commissioner for Accounting for Child Sexual Abuse, Dr. Christine Bergmann”  published in May 2011 clearly demonstrates – especially by the integrated statements of the people concerned – how severely childhood traumatization can affect later life. With regard to the consequences of abuse, somatic complaints were reported starting at a rate of 50%, followed by relationship- and partnership problems, a row of symptoms typical of post-traumatic stress, performance impairment in connection with poorer school results, problems in professional education, occupational disability, etc., problems with self-esteem, self-hatred and self-disgust up to problems with corporeality and sexuality in even more than one fifth of the persons concerned.
Besides Post-Traumatic Stress Disorder (PTSD) – a trauma-related disorder by definition – increased risks after childhood traumatization have been shown and connections proven, respectively, in the following selected mental illnesses in retrospective and partly also prospective studies: depressive disorders [7, 9, 12, 13, 16–19], anxiety disorders [7, 12, 16, 17, 20], addictions [7, 12, 13, 16–18, 21, 22], somatoform disorders [7, 9, 23–28], personality disorders [12, 18, 29–31] and conduct disorder [12, 16, 17, 29]. The same applies to the following somatic diseases: overweight [3, 13, 19, 32, 33], diabetes mellitus [13, 32, 34, 35], hypertension [36, 37] and ischemic heart diseases [13, 38–41]. The strength of the association between traumatization and trauma-related disorder reported in the aforementioned studies varies due to different approaches and methodologies.
Trauma-related disorders are thus by no means limited to the time of traumatization; they often accompany patients throughout their lives, with the time lag to the trauma being highly variable. While PTSD is defined over a close time connection of several weeks or months , trauma-related disorders such as depression, anxiety disorders, addiction or obesity can occur even in adulthood, i.e., years to decades after traumatization . The far-reaching consequences of trauma-associated developmental disorders [43, 44] and the multifaceted manifestation of trauma-related disorders, which affect various areas of life such as education, social contacts and working ability, are also mirrored in the high comorbidity rates that have been proven comprehensively for mental and somatic disorders in large studies [5, 7, 12, 13, 45–47].
However, childhood traumatization can by no means be regarded as the sole cause of the development of diseases or disorders . Traumatization represents one of several variables in a biopsychosocial model, which measurably increases the risk of suffering from a certain disease or disorder. The extent of this risk increase varies depending on the type and severity of traumatization, individual conditions (e.g. gender) and the influence of external risk- and protective factors [2, 23, 48–50].
Costs of childhood traumatization
Up to now, there are only few sources examining the cost side of childhood traumatization and the relevant social- and health policy questions. The total societal costs incurring due to childhood traumatization (hereinafter referred to as trauma follow-up costs) are unknown. A few studies from English-speaking countries have attempted to give at least approximate estimates of trauma follow-up costs. Authors of a cost-benefit analysis by the National Center of Early Assistance (NZFH, Nationales Zentrum Frühe Hilfen)  express concern that national studies on trauma follow-up costs are neither available nor feasible in Germany due to the non-availability of data.
What all studies known to the authors have in common is great uncertainty and incompleteness of the available data – starting from the prevalence of traumatization over the definition of cost areas to the calculation and allocation of costs. The variability of individual progressions between complete resilience and lifelong trauma-related disorders must be estimated as well, since they directly determine the long-term follow-up costs. By means of their conservative calculation methodology, studies on trauma follow-up costs explain in detail that the results of this puzzle are throughout underestimating [52–58]. In summary, underestimation is most notably explained by the insufficient availability of relevant data, which leaves certain cost areas partially or completely out of consideration, and by the uncertainty with regard to trauma prevalence, the dark figure of which (estimated number of unknown cases) can at best be taken into consideration but approximately.
One US-American study estimates societal costs related to reported cases of child abuse and neglect at USD 103.8 billion per year – without taking intangible costs into consideration . For Australia, trauma follow-up costs have been calculated for the year 2007 in the amount of approximately AUD 4.0 billion on the basis of a population survey and in the amount of AUD 10.7 billion on the basis of prevalence information from literature . In Canada, the annual amount is around CAD 15.7 billion – calculated as "a minimum cost to society" . In the US state of Michigan, two consecutive cost-benefit studies refer to costs in the amount of USD 823 million for the year 1992  and USD 1.8 billion for the year 2002 . A cost-benefit study conducted in the state of New York quotes USD 9.0 million per year for "catastrophic maltreatment" .
Sources about federal costs in Germany are not known to the authors. The objectives of the present study are to estimate societal trauma-follow up costs (including direct and indirect costs) in Germany for the first time and to compare the results to costs in Australia, Canada and the USA.
Derivation of the total trauma follow-up costs
This prevalence-based cost-of-illness study is performed from the societal perspective. This perspective comprises not only individual costs, but most of all costs borne by society, caused by expenses in cost sectors such as health insurance, social service or losses in added value. The costs include those directly linked to traumatization as well as short- and long-term costs occurring due to aftereffects (indirect costs). The insufficiency of the available data did not allow for any estimation of opportunity costs. In order to estimate annual trauma follow-up costs in Germany, already published, aggregated data was used. The cost derivation follows a bottom-up approach based on the following formula:
Number of "A" units x costs per unit "A" = Total cost of "A" units.
In this context, unit "A" represents a case of (former) child abuse and/or neglect, respectively, where trauma-related disorders incur additional, economical costs for a lifetime.
Characteristics of the German prevalence study
Retrospective population survey
Prevalence of child maltreatment (physical, emotional, sexual) and neglect (physical, emotional) in Germany
Representative of the German population
Sample size: 2,504
Females: 53.2%, males 46.8%
Age: 14–90 years, mean value: 50.6 years
Assessment of child maltreatment and neglect through the Childhood Trauma Questionnaire (German version)
Characteristics of the German cost study
Assessment of cost and benefit of an Early Family Assistance Program
One prevention scenario versus four scenarios under the assumption of early child endangerment (child abuse and neglect fall within this definition)
Case scenarios based on literature and expert knowledge
Costs modeled on the basis of available data, supplemented by literature
Healthcare services, social services, educational services and losses in productivity (due to low professional qualification, unemployment and occupational disability)
Different types of educational family/parent support and foster care
Treatment of trauma-related disorders, educational services and productivity losses
In order to account for uncertainty, sensitivity analysis was performed by estimating a frame of trauma follow-up costs, based on the two different scenario types. Because of the great uncertainty of the information base and the lack of alternative resources, this cost-of-illness study follows a conservative approach. In order to abide by this principle and to create a coherent age range several adjustments had to be applied to prevalence and to cost data.
At first, the prevalence rate  was transferred to the German population utilizing population data from the German Federal Statistical Office . From the given age groups the range of 15 to 64 years was the one that conformed best with the age ranges of the prevalence rate (≥ 14 years) and cost data (3 to 67 years). The exclusion of individuals aged 65 years and more is not expected to have any relevant influence on the prevalence rate, because only physical neglect was associated with a slightly higher risk in elderly persons (OR 1.03) .
Secondly, due to the individually different histories after traumatization, it cannot be assumed that all traumatized persons will suffer lifelong aftereffects [23, 50], in particular not in an extent that would incur further costs in the dimension described later. Therefore, only the prevalence of "severe/extreme" cases as defined by the CTQ was considered.
Yet even for the group of "severely/extremely" affected, it is not clear to what extent the consequences of trauma are reflected as measurable costs. Since one of the few available German studies  estimates the frequency of permanently impaired children among severely affected cases in child protection centers to be 21% (including cases of developmental retardation and learning disability), the authors have decided to use this 21% rate for derivation.
Furthermore, the case costs were adjusted for the age range of 15 to 64 years as defined by population data. As a consequence, the matters of expense in the years below and above that age range were deducted. This step was made on the assumption that costs are homogeneously distributed throughout the highest age group (51 to 67 years), whereas in the age group of 13 to 16 years the single matter of expense is considered in relation to the corresponding age.
Finally, the case costs were converted into annual costs by dividing them by the age range of 50 years (15 up to including 64 years). The case scenarios are presented on the 2008 cost level . Consequently, total trauma follow-up costs are quoted in Euro for the year 2008. Since other years' cost figures are not included, no discounting was applied.
Calculation of international comparative values
Characteristics of the Cost Studies used for International Comparison
Annual Costs* (million)
Australia :AUD 3,947**
One-year prevalence in 0-17-year-olds: 3.7% (based on a population survey on physical and sexual abuse)
Short- and long-term costs of physical, emotional and psychological, sexual abuse, neglect and witness of (or knowledge of) family violence by a combination of top-down and bottom-up methods
Health, Additional educational assistance, Productivity losses of child abuse survivors and due to premature death, Crime, Government expenditures on care and protection, Deadweight losses
Canada :CAD 15,706
Lifetime prevalence in 15-64-year-olds: 30% total, 14.6% severe (based on a population survey on physical and sexual abuse); Lifetime prevalence in 0-14-year-olds: 6.89% (based on the number of investigated cases of physical, emotional, sexual abuse or neglect)
Short- and long-term costs of physical, emotional, sexual abuse, neglect and witnessing violence by a combination of top-down and bottom-up methods
Judicial, Social Services, Education, Health, Employment, Personal
USA :USD 7,300
Number of 0-17-year-old abuse victims (sexual, emotional and physical) in the year 1990: 794,000 (based on a national study of recognized child abuse and neglect); equal to 1,24% of that age group [own calculation]
Short- and long-term costs of physical, sexual and emotional abuse by a combination of top-down and bottom-up methods
Productivity, Medical Care/Ambulance, Mental Health Care, Police/Fire Services, Social/Victim Services, Property Loss/Damage
Additionally, the international costs were calculated as notional total costs for Germany by multiplying per capita costs of the respective country by the German population. These figures serve as a complementary way of illustrating the results, in order to point out the cost dimension of traumatization in relation to other societal expenses.
By means of these methods, differences between the individual countries with regard to purchasing power, population size and currency shall be balanced, so that results can be compared in the form of single figures on one level.
Total trauma follow-up costs
The prevalence rate of at least one form of child abuse or neglect classified as "severe/extreme" is 14.5% . This 14.5% share transferred to the German population aged between 15 and 64 years (54.1 million in the year 2008 ), the number of people concerned would be 7.8 million.
On the basis of the indications available in literature, only a 21% share of the 7.8 million individuals affected by “severe/extreme” child abuse or neglect has been included in the derivation of costs. This percentage equals 1.6 million (or 3.0% of the population aged 15 to 64 years), which represent the number of units "A".
The costs of the moderate scenarios average to EUR 432,951 (mean value of EUR 424,005 and EUR 441,896) for the age range of three to 67-year-olds; of the pessimistic scenarios, the average costs are EUR 1,159,294 (mean value of EUR 1,243,002 and EUR 1,075,585) for the age range of six to 67-year-olds . By adjusting the costs for the age range of 15 to 64 years, average costs are reduced to a total of EUR 335,421 (mean value of EUR 326,745 and EUR 344,096) in the moderate scenario and to EUR 904,375 (mean value of EUR 870,579 and EUR 938,169) in the pessimistic scenario. The resulting average annual costs, related to a period of 50 years, amount to EUR 6,708 per unit "A" in the moderate scenario and to EUR 18,087 in the pessimistic scenario.
the resulting total annual costs amount to EUR 11.1 billion, which incur as follow-up costs of child abuse and neglect, respectively, for German society. In other words, the annual per capita trauma follow-up costs would amount to EUR 134.84 (German population 2008: 82,002,400 ).
the upper bound of the annual trauma follow-up cost frame is EUR 29.8 billion in total or EUR 363.58 per capita.
International comparative values
Conversion of International Cost Values into Euro in the Year 2008
Original total annual costs in national currency
Total annual costs in Euro, different cost years
Total annual costs in Euro, 2008
Per capita costs* in Euro, different cost years
Per capita costs* in Euro, 2008
Australia, without intangible costs 
Australia, including intangible costs 
USA, without intangible costs 
USA, including intangible costs 
Canada, without intangible costs 
The German lower bound in the amount of EUR 11.1 billion per year is close to the Australian result, while the Canadian study has returned costs very close to the German upper bound. The US-American study is somewhat out of scope with about one sixth of the German lower bound costs.
The Australian and US-American studies additionally quote intangible costs, whereby results are increased to EUR 287.67 and EUR 169.81, respectively, per capita (EUR 23.6 billion and EUR 13.9 billion total costs).
Total trauma follow-up costs
The objective of the present study was to estimate trauma follow-up costs for Germany. A margin of total annual trauma follow-up costs was calculated in the amount of EUR 11.1 billion for the lower bound and EUR 29.8 billion for the upper bound, respectively. The correspondence of the Australian result with Germany’s lower bound should be considered with utmost caution, since both cost studies are based on completely different methods and also include different cost areas. In contrast to the Australian study , the German cost calculation  does not take crime and deadweight losses into consideration, whereas the areas health, education, productivity and social services have been considered equally.
In both studies, prevalence is based on a population survey with similar results for the lifetime prevalence of physical and sexual abuse (17.8% in Australia  and approximately 15.9% in Germany [10, own calculation]). However, the Australian study uses only the one-year prevalence of 0 to 17- year-olds and does not include emotional abuse or neglect. Thus, the number of people concerned is much lower in the Australian study, whereas the total costs per person must lie close to those of Germany’s upper bound: the upper bound costs (EUR 18,087) multiplied by Australia’s prevalence (3.7% of Germany’s population aged 0–15 years: 412.147, age range as presented by the German Federal Statistical Office ) would yield – with EUR 7.5 billion – a result quite close to the Australian one.
The Canadian result  is very close to the German upper bound, but relies on higher prevalence rates (cf. Table 3), which have been used for cost calculation in a sophisticated way. Canadian costs comprise expenses related to the legal system, social services, education, health, employment and personal costs, with the employment sector being the most expensive one, accounting for 72% of the total costs (CAD 11.3 billion of a total of CAD 15.7 billion). Other than in the Australian and US-American studies, Canada has based their cost calculation in the employment sector on a large population survey, which combined information on income with physical and sexual abuse in the respondents' history (Ontario Health Survey Mental Health Supplement (OHSUP)).
With a loss of productivity of over 70% in the moderate case scenarios and over 50% in the pessimistic ones, the German cost-benefit-analysis  ranks close to the Canadian result. Since costs are oriented towards individual life courses in both countries – in Canada on the basis of a population survey and in Germany on the basis of individual case scenarios – this result could in fact point in the right direction, namely to regarding productivity losses as the main cost driver of societal trauma follow-up costs. The other two studies [52, 53] rely on less specific, aggregated data. In Australia , losses of productivity rank far behind the other areas, while an approximate proportion of almost 30% can be derivated for the United States .
The total costs in the United States  are considerably lower than those in other countries, even though the cost sectors taken into consideration largely correspond. However, on the one hand, child neglect is not included for methodological reasons, and on the other hand, the number of child abuse victims is not determined on the basis of a population survey, but official information sources are used . Despite the attempt to calculate institutionally unknown cases, the dark figure remains largely unconsidered. There is naturally no precise information regarding the magnitude of this dark figure. Wetzels  indicates an optimistic estimate at the ratio of one to ten. This estimate projected on the US-American study would yield a result of EUR 18 billion instead of EUR 1.8 billion and thus above the Australian costs and within the German cost frame.
The two results from Australia  and the United States , which contain intangible costs, cannot be compared with the German result (without intangible costs). In the Australian study, intangible costs make up for 1.7 times, in the US-American study even 6.7 times of the tangible costs. In spite of this large difference it can be stated on the transnational level that intangible costs as a measure for personally experienced burden considerably exceed the actual expenses in the form of tangible costs in any case.
Generally, the comparison of the four aforementioned results of trauma follow-up costs is limited due to the time lag of altogether fifteen years between the individual studies, which have certainly influenced prices, services and their utilization. Additionally, national service organization and funding structures, e.g. of the health care systems, are fundamentally different . These variations presumably influence the availability and the assessment of costs and their assignment to various sectors, so that differences in costs are to be expected a priori due to structural conditions.
The calculated amount of trauma follow-up costs clearly has economic relevance, constituting 0.44% (lower bound) and 1.20% (upper bound) of Germany’s 2008 Gross Domestic Product (EUR 2,489.4 billion) . The figures have an additional relevance due to the fact that with early and effective intervention or prevention, they reveal a considerable saving potential [9, 51, 56–58].
Basically, trauma follow-up costs were determined by following a conservative approach. This is reflected in several details, for example in the restriction to a 21% share of only severely affected cases [4, 10]. Results of risk- and resilience research lie around this value for the share of traumatized individuals with long-term consequences caused by trauma-related disorders [50, 68].
Moreover, total costs have only been taken into account for the age group from 15 up to including 64 years. Consequently, direct costs are only considered to a small extent and indirect costs of older ages remain completely excluded. With existing trauma-related disorders, it can be assumed that the age-related, increasing instability of life situation leads to further health problems, which again incur additional costs in higher age. In general, trauma-related disorders do not tend to decrease in higher age [1, 69], but elderly people are often severely impaired due to e.g., insufficient specialized care .
Last but not least it should be noted that types of traumatization other than sexual, physical and emotional abuse and neglect are left unconsidered in the present study, so that no statements can be made on their prevalence or on follow-up costs. However, it appears reasonable to limit the derivation of trauma follow-up costs to child abuse and neglect, since other current data are not available and international cost studies [52–58] refer to these types of traumatization exclusively or predominantly, so that results can be better compared with each other.
When trying to estimate whether the true costs may tend towards the lower or the upper bound one has to keep in mind that the cost scenarios are based on early childhood traumatization, whereas the prevalence data include the entire childhood and adolescence as defined by the CTQ. Since trauma-related disorders tend to be more severe the earlier traumatization was experienced [2, 70], this discrepancy leads in the direction of the lower bound.
The international comparison supports both the lower and the upper bound of the cost margin – depending on the respective study. Due to methodological differences the results have to be interpreted rather as crude reference points, though. Despite all limitations, the comparison shows that the cost margin calculated for Germany is well associated with other countries’ results.
Limitations associated with the use of already existing data are particularly given by the fact that these data have been collected with different objectives and are not well-matched. The question arises, in particular, to what extent the cost scenarios – determined under the assumption of child endangerment  – can be projected on the number of traumatized individuals identified in epidemiologic studies [4, 10]. While various age limits of the investigated populations can be approximated, it cannot be stated with certainty whether the cost scenarios described by Meier-Gräwe and Wagenknecht  are based on the same kind of traumatization as the determination of prevalence by Häuser et al. .
The prevalence of traumatization has been determined by Häuser et al.  retrospectively, which may represent yet another source of error – due to blurred or imprecise memories. However, several studies of this kind illustrate the fact very well that the number of errors is to be estimated rather low and of conservative type, in other words, that the results tend to underestimate reality [3, 5, 11, 20, 45, 71, 72].
Another significant uncertainty lies in the cost data themselves. The authors of the cost study explain in detail that due to the lack of data, several parts had to be completed by expert knowledge and international literature . The complete case scenarios are thus but a construct, which has been developed as close to reality as possible with the help of various information sources.
The problem of low availability and unsatisfactory quality of the data with regard to the estimation of trauma follow-up costs does not only exist in Germany but it is criticized in all cost studies [52–58]. Consequently, results are consistently presented as fragmentary and underestimating. Since it can therefore be assumed that all cost studies deviate from reality in the same direction – with the extent of deviation being unclear – a comparison is possible and reasonable. Nevertheless, it can only be valued as a comparison of cost dimensions, not of amounts calculated precisely to the cent, solely due to the different methodologies. In view of the generally weak data, it should be noted that by using more precise procedures, only the illusion of higher precision could be created. This is not the intention of the authors.
Realizing numerous questions and imponderabilities in the assessment of results, creating a reliable data basis must be of highest priority in Germany, in order to answer the question how expensive it is not to provide sufficient and timely assistance to traumatized children and juveniles. The gathering of reliable cost data seems to be a highly challenging task in the light of an extremely fragmentary information basis. Serious efforts should therefore be undertaken to collect reliable data, in the first place. Only on the basis of results that are accepted by all sides due to their validity can steps be ground in order to sustainably improve the status quo of prevention and post-traumatic care.
Starting points for the improvement of care and thus assumingly also for long-term cost savings are indicated in numerous literature sources, which, for example demand a stronger interconnectedness of the respective institutions [15, 73–77] or a more specific qualification in the medical community [15, 78–81]. Fiscally responsible decision-making, though, should rely on the economic evaluation of any intervention or prevention program .
Total costs of EUR 11.1 billion or EUR 29.8 billion, respectively, for the consequences of childhood traumatization by various types of severe child abuse as well as neglect are undoubtedly relevant for German economy. Considering the paucity of data, especially of cost data, the result cannot be seen without restrictions. Therefore serious efforts should be undertaken to generate reliable data, in the first place.
Besides the question of personal suffering, political decision-makers should pay much more attention to the economic perspective of childhood traumatization and its comprehensive dimension of long-term consequences. By improving trauma-related care and prevention, the societal economic burden might be reduced.
SH has worked as a medical doctor before additionally graduating in Public Health. She specialized in DRG-based hospital reimbursement while working in the German DRG-Institute (Institut für das Entgeltsystem im Krankenhaus GmbH). Currently, SH is working on different health economics-related projects.
SB holds a Master of Science and a PhD in Economics. During the progress of this paper she has worked as JMF’s Executive Assistant at the Hospital for Child and Adolescent Psychiatry and Psychotherapy of the Ulm University Hospital. Currently she is working at the Baden-Württembergische Krankenhausgesellschaft, a regional association of hospitals.
JW is neurologist and psychiatrist, specialized in psychotherapy and psychoanalysis. Over a period of many years he has gained comprehensive and multifaceted experiences in Health Management, e.g. as Medical Director or Health Management Consultant, most recently as Managing Director at Asklepios Medical School GmbH.
JMF is child and adolescent psychiatrist and psychotherapist. He is Medical Director and founder of the Hospital for Child and Adolescent Psychiatry and Psychotherapy at the Ulm University Hospital. He is member of the Scientific Board for Family Affairs at the Bundesministerium für Familie, Senioren, Frauen und Jugend (BMFSFJ), and since 2010 he is deputy chairman of this board.
Childhood Trauma Questionnaire
National Center of Early Assistance (Nationales Zentrum Frühe Hilfen)
Post Traumatic Stress Disorder.
First and foremost, the authors are grateful to the Bundesministerium für Familie, Senioren, Frauen und Jugend (BMFSFJ) for having provided funding for the study, and thus allowing this important issue to be analyzed and the results to be published. Special thanks go to Almut Hornschild-Rentsch and her team who accompanied the development of the study.
We thank Anna Herboly for her excellent work on editing the manuscript.
Last but not least, we would like to thank the library of Asklepios Medical School GmbH in Hamburg, namely Sabrina Juhst, Birgit Scherpe and Verena Reiser, for their straightforward support by providing the literature needed.
- Maercker A, Forstmeier S, Wagner B, Brähler E, Glaesmer H: Posttraumatische Belastungsstörungen in Deutschland. Ergebnisse einer gesamtdeutschen epidemiologischen Untersuchung. Nervenarzt. 2008, 79: 577-586. 10.1007/s00115-008-2467-5.View ArticlePubMedGoogle Scholar
- Steil R, Straube ER: Posttraumatische Belastungsstörung bei Kindern und Jugendlichen. Z Klin Psychol Psychother. 2002, 31: 1-13. 10.1026//1616-34126.96.36.199.View ArticleGoogle Scholar
- Gilbert R, Widom CS, Browne K, Fergusson D, Webb E, Janson S: Burden and consequences of child maltreatment in high-income countries. Lancet. 2009, 373: 68-81. 10.1016/S0140-6736(08)61706-7.View ArticlePubMedGoogle Scholar
- Thyen U, Kirchhofer F, Wattam C: Gewalterfahrung in der Kindheit – Risiken und gesundheitliche Folgen. Gesundheitswesen. 2000, 62: 311-319. 10.1055/s-2000-11468.View ArticlePubMedGoogle Scholar
- Kessler RC, Sonnega A, Bromet E, Hughes M, Nelson CB: Posttraumatic Stress Disorder in the National Comorbidity Survey. Arch Gen Psychiatry. 1995, 52: 1048-1060. 10.1001/archpsyc.1995.03950240066012.View ArticlePubMedGoogle Scholar
- Wetzels P: Gewalterfahrungen in der Kindheit. Sexueller Mißbrauch, körperliche Mißhandlung und deren langfristige Konsequenzen. 1997, Baden Baden: Nomos. [Criminological Research Institute of Lower Saxony (Series Editor)Interdisziplinäre Beiträge zur kriminologischen Forschung, vol 8.]Google Scholar
- Perkonigg A, Kessler RC, Storz S, Wittchen H-U: Traumatic events and post-traumatic stress disorder in the community: prevalence, risk factors and comorbidity. Acta Psychiatr Scand. 2000, 101: 46-59. 10.1034/j.1600-0447.2000.101001046.x.View ArticlePubMedGoogle Scholar
- Essau CA, Conradt J, Petermann F: Häufigkeit der Posttraumatischen Belastungsstörung bei Jugendlichen: Ergebnisse der Bremer Jugendstudie. Z Kinder Jugendpsychiatr Psychother. 1999, 27: 37-45. 10.1024//1422-49188.8.131.52.View ArticlePubMedGoogle Scholar
- Felitti VJ, Anda RF: The relationship of adverse childhood experiences to adult medical disease, psychiatric disorders, and sexual behavior: implications for healthcare. The Impact of Early Life Trauma on Health and Disease: The Hidden Epidemic. Edited by: Lanius RA, Vermetten E, Pain C. 2010, New York: Cambridge University Press, 77-87. 1View ArticleGoogle Scholar
- Häuser W, Schmutzer G, Brähler E, Glaesmer H: Misshandlungen in Kindheit und Jugend: Ergebnisse einer Umfrage in einer repräsentativen Stichprobe der deutschen Bevölkerung. Dtsch Arztebl Int. 2011, 108: 287-294.PubMed CentralPubMedGoogle Scholar
- MacMillan HL, Fleming JE, Trocmé N, Boyle MH, Wong M, Racine YA, Beardslee WR, Offord DR: Prevalence of child physical and sexual abuse in the community. Results from the Ontario health supplement. JAMA. 1997, 278: 131-135. 10.1001/jama.1997.03550020063039.View ArticlePubMedGoogle Scholar
- Kessler R, Davis CG, Kendler KS: Childhood adversity and adult psychiatric disorder in the US National Comorbidity Survey. Psychol Med. 1997, 27: 1101-1119. 10.1017/S0033291797005588.View ArticlePubMedGoogle Scholar
- Felitti VJ, Anda RF, Nordenberg D, Williamson DF, Spitz AM, Edwards V, Koss MP, Marks JS: Relationship of childhood abuse and household dysfunction to many of the leading causes of death in adults. The adverse childhood experiences study (ACE). Am J Prev Med. 1998, 14: 245-258. 10.1016/S0749-3797(98)00017-8.View ArticlePubMedGoogle Scholar
- Putnam FW: The impact of trauma on child development. Juv Fam Ct J. 2006, 57: 1-11.View ArticleGoogle Scholar
- Geschäftsstelle der Unabhängigen Beauftragten zur Aufarbeitung des sexuellen Kindesmissbrauchs: Abschlussbericht der Unabhängigen Beauftragten zur Aufarbeitung des sexuellen Kindesmissbrauchs, Dr. Christine Bergmann. 2011, BerlinGoogle Scholar
- Nelson EC, Heath AC, Madden PAF, Cooper ML, Dinwiddie SH, Bucholz KK, Glowinski A, McLaughlin T, Dunne MP, Statham DJ, Martin NG: Association between self-reported childhood sexual abuse and adverse psychosocial outcomes. Arch Gen Psychiatry. 2002, 59: 139-145. 10.1001/archpsyc.59.2.139.View ArticlePubMedGoogle Scholar
- Fergusson DM, Horwood LJ, Lynskey MT: Childhood sexual abuse and psychiatric disorder in young adulthood: II. Psychiatric outcomes of childhood sexual abuse. J Am Acad Child Adolesc Psychiatry. 1996, 34: 1365-1374.View ArticleGoogle Scholar
- Silverman AB, Reinherz HZ, Giaconia RM: The long-term sequelae of child and adolescent abuse: a longitudinal community study. Child Abuse Negl. 1996, 20: 709-723. 10.1016/0145-2134(96)00059-2.View ArticlePubMedGoogle Scholar
- Rohde P, Ichikawa L, Simon GE, Judmann EJ, Linde JA, Jeffery RW, Operskalski BA: Associations of child sexual and physical abuse with obesity and depression in middle-aged women. Child Abuse Negl. 2008, 32: 878-887. 10.1016/j.chiabu.2007.11.004.PubMed CentralView ArticlePubMedGoogle Scholar
- Goodwin RD, Fergusson DM, Horwood LJ: Childhood abuse and familial violence and the risk of panic attacks and panic disorder in young adulthood. Psychol Med. 2005, 35: 881-890. 10.1017/S0033291704003265.View ArticlePubMedGoogle Scholar
- Schäfer M, Schnack B, Soyka M: Sexueller und körperlicher Mißbrauch während früher Kindheit oder Adoleszenz bei späterer Drogenabhängigkeit. PPmP Psychother Psychosom med Psychol. 2000, 50: 38-50. 10.1055/s-2000-13235.View ArticleGoogle Scholar
- European Monitoring Centre for Drugs and Drug Addiction (EMCDDA): Preventing later substance use disorders in at-risk children and adolescents: a review of the theory and evidence base of indicated prevention. Thematic papers. 2009, Luxembourg: Office for Official Publications of the European Communities,http://www.emcdda.europa.eu/publications/thematic-papers/indicated-prevention.Google Scholar
- Egle UT, Hoffmann SO, Steffens M: Psychosoziale Risiko- und Schutzfaktoren in Kindheit und Jugend als Prädisposition für psychische Störungen im Erwachsenenalter. Nervenarzt. 1997, 68: 683-695. 10.1007/s001150050183.View ArticlePubMedGoogle Scholar
- Waldinger RJ, Schulz MS, Barsky AJ, Ahern DK: Mapping the road from childhood trauma to adult somatization: the role of attachment. Psychosom Med. 2006, 68: 129-135. 10.1097/01.psy.0000195834.37094.a4.View ArticlePubMedGoogle Scholar
- Sansone RA, Wiederman MW, Sansone LA: Adult somatic preoccupation and its relationship to childhood trauma. Violence Vict. 2001, 16: 39-47.PubMedGoogle Scholar
- Sansone RA, Gaither GA, Sansone LA: Childhood trauma and adult somatic preoccupation by body area among women in an internal medicine setting: a pilot study. Int J Psychiatry Med. 2001, 31: 147-154. 10.2190/TC5A-07AK-50RU-R2RG.View ArticlePubMedGoogle Scholar
- Walker EA, Katon WJ, Roy-Byrne PP, Jemelka RP, Russo J: Histories of sexual victimization in patients with irritable bowel syndrome or inflammatory bowel disease. Am J Psychiatry. 1993, 150: 1502-1506.View ArticlePubMedGoogle Scholar
- Barsky AJ, Wool C, Barnett MC, Cleary PD: Histories of childhood trauma in adult hypochondriacal patients. Am J Psychiatry. 1994, 151: 397-401.View ArticlePubMedGoogle Scholar
- Spataro J, Mullen PE, Burgess PM, Wells DL, Moss SA: Impact of child sexual abuse on mental health. Br J Psychiatry. 2004, 184: 416-421. 10.1192/bjp.184.5.416.View ArticlePubMedGoogle Scholar
- Kopp D, Spitzer C, Kuwert P, Barnow S, Orlob S, Lüth H, Freyberger HJ, Dudeck M: Psychische Störungen und Kindheitstraumata bei Strafgefangenen mit antisozialer Persönlichkeitsstörung. Fortschr Neurol Psychiat. 2009, 77: 152-159. 10.1055/s-0028-1109150.View ArticlePubMedGoogle Scholar
- Luntz BK, Widom CS: Antisocial personality disorder in abused and neglected children grown up. Am J Psychiatry. 1994, 151: 670-674.View ArticlePubMedGoogle Scholar
- Thomas C, Hyppönen E, Power C: Obesity and type 2 diabetes risk in midadult life: the role of childhood adversity. Pediatrics. 2008, 121: e1240-1249. 10.1542/peds.2007-2403.View ArticlePubMedGoogle Scholar
- Williamson DF, Thompson TJ, Anda RF, Dietz WH, Felitti V: Body weight and obesity in adults and self-reported abuse in childhood. Int J Obes Relat Metab Disord. 2002, 26: 1075-1082. 10.1038/sj.ijo.0802038.View ArticlePubMedGoogle Scholar
- Rich-Edwards JW, Spiegelman D, Lividoti Hibert EN, Jun HJ, Todd TJ, Kawachi I, Wright RJ: Abuse in childhood and adolescence as a predictor of type 2 diabetes in adult women. Am J Prev Med. 2010, 39: 529-536. 10.1016/j.amepre.2010.09.007.PubMed CentralView ArticlePubMedGoogle Scholar
- Kendall-Tackett KA, Marshall R: Victimization and diabetes: an exploratory study. Child Abuse Negl. 1999, 23: 593-596. 10.1016/S0145-2134(99)00033-2.View ArticlePubMedGoogle Scholar
- Riley EH, Wright RJ, Jun HJ, Hibert EN, Rich-Edwards JW: Hypertension in adult survivors of child abuse: observations from the Nurses' health study II. J Epidemiol Community Health. 2010, 64: 413-418. 10.1136/jech.2009.095109.PubMed CentralView ArticlePubMedGoogle Scholar
- Stein DJ, Scott K, Haro Abad JM, Aguilar-Gaxiola S, Alonso J, Angermeyer M, Demytteneare K, de Girolamo G, Iwata N, Posada-Villa J, Kovess V, Lara C, Ormel J, Kessler RC, Von Korff M: Early childhood adversity and later hypertension: data from the World Mental Health Survey. Ann Clin Psychiatry. 2010, 22: 19-28.PubMed CentralPubMedGoogle Scholar
- Dong M, Giles WH, Felitti VJ, Dube SR, Williams JE, Chapman DP, Anda RF: Insights into causal pathways for ischemic heart disease: adverse childhood experiences study. Circulation. 2004, 110: 1761-1766. 10.1161/01.CIR.0000143074.54995.7F.View ArticlePubMedGoogle Scholar
- Roy A, Janal MN, Roy M: Childhood trauma and prevalence of cardiovascular disease in patients with type 1 diabetes. Psychosom Med. 2010, 72: 833-838. 10.1097/PSY.0b013e3181eafc2d.View ArticlePubMedGoogle Scholar
- Fuller-Thomson E, Brennenstuhl S, Frank J: The association between childhood physical abuse and heart disease in adulthood: findings from a representative community sample. Child Abuse Negl. 2010, 34: 689-698. 10.1016/j.chiabu.2010.02.005.View ArticlePubMedGoogle Scholar
- Goodwin RD, Stein MB: Association between childhood trauma and physical disorders among adults in the United States. Psychol Med. 2004, 34: 509-520. 10.1017/S003329170300134X.View ArticlePubMedGoogle Scholar
- German Institute of Medical Documentation and Information, DIMDI: Internationale statistische Klassifikation der Krankheiten und verwandter Gesundheitsprobleme, 10. Revision, German Modification (ICD-10-GM), Version. 2011,http://www.dimdi.de/static/de/klassi/icd-10-gm/kodesuche/onlinefassungen/htmlgm2011/index.htm.Google Scholar
- Schmid M, Fegert JM, Petermann F: Traumaentwicklungsstörung: Pro und Contra. Kindheit und Entwicklung. 2010, 19: 47-63. 10.1026/0942-5403/a000008.View ArticleGoogle Scholar
- Knudsen EI, Heckman JJ, Cameron JL, Shonkoff JP: Economic, neurobiological, and behavioral perspectives on building America’s future workforce. Proc Natl Acad Sci. 2006, 103: 10155-10162. 10.1073/pnas.0600888103.PubMed CentralView ArticlePubMedGoogle Scholar
- Anda RF, Felitti VJ, Bremner D, Walker JD, Whitfield C, Perry BD, Dube SR, Giles WH: he enduring effects of abuse and related adverse experiences in childhood. A convergence of evidence of neurobiology and epidemiology. Eur Arch Psychiatry Clin Neurosci. 2006, 256: 174-186. 10.1007/s00406-005-0624-4.PubMed CentralView ArticlePubMedGoogle Scholar
- Van der Kolk BA, Pynoos RS, Cicchetti D, Cloitre M, D’Andrea W, Ford JD, Lieberman AF, Putnam FW, Saxe G, Spinazzola J, Stolbach BC, Teicher M: Proposal to include a developmental trauma disorder diagnosis for children and adolescents in DSM-V.http://www.traumacenter.org/announcements/DTD_papers_Oct_09.pdf.
- Perkonigg A, Wittchen H-U, et al: Prevalence and comorbidity of traumatic events and posttraumatic stress disorder in adolescents and young adults. Posttraumatic stress disorder: a lifespan developmental perspective. Edited by: Maercker A, Schützwohl M. 1999, Seattle, Toronto, Bern, Göttingen: Hogrefe & Huber, 113-133. 1Google Scholar
- Caspi A, McClay J, Moffitt TE, Mill J, Martin J, Craig IW, Taylor A, Poulton R: Role of genotype in the cycle of violence in maltreated children. Science. 2002, 297: 851-854. 10.1126/science.1072290.View ArticlePubMedGoogle Scholar
- Häfner S, Franz M, Lieberz K, Schepank H: Psychosoziale Risiko- und Schutzfaktoren für psychische Störungen: Stand der Forschung. Teil 2 Psychosoziale Schutzfaktoren. Psychotherapeut. 2001, 46: 403-408. 10.1007/PL00006733.View ArticleGoogle Scholar
- Werner EE: Vulnerable but invincible: High risk children from birth to adulthood. Eur Child Adolesc Psychiatry. 1996, 5: 47-51. 10.1007/BF00538544.View ArticlePubMedGoogle Scholar
- Meier-Gräwe U, Wagenknecht I: Expertise Kosten und Nutzen Früher Hilfen. 2011, Köln: Nationales Zentrum Frühe HilfenGoogle Scholar
- Miller TR, Cohen MA, Wiersema B: Victim costs and consequences: a New look. 1996, Washington, DC: U.S: Department of Justice, National Institute of JusticeGoogle Scholar
- Taylor P, Moore P, Pezzullo L, Tucci J, Goddard C, De Bortoli L: The cost of child abuse in Australia. 2008, Melbourne: Australian Childhood Foundation and Child Abuse Prevention Research AustraliaGoogle Scholar
- Wang C-T, Holton J: Total estimated cost of child abuse and neglect in the united states. Economic impact study. 2007, Chicago, Illinois: Prevent Child Abuse AmericaGoogle Scholar
- Bowlus A, McKenna K, Day T, Wright D: The Economic Costs and Consequences of Child Abuse in Canada. 2003, Ottawa: Law Commission of CanadaGoogle Scholar
- Caldwell RA: The costs of child abuse vs. Child abuse prevention: Michigan's experience. 1992, Lansing: Michigan Children's Trust FundGoogle Scholar
- Noor I, Caldwell RA: The costs of child abuse vs. Child abuse prevention: a multi-year follow-up in Michigan. 2005, Lansing: Michigan Children's Trust FundGoogle Scholar
- Nobuyasu S: Costs and Benefit Simulation Analysis of Catastrophic Maltreatment. The cost of child maltreatment: Who pays? We all do. Edited by: Franey K, Geffner R, Falconer R. 2001, San Diego: Family Violence and Sexual Assault Institute, 199-210. 1Google Scholar
- Statistisches Bundesamt – German Federal Statistical Office: Bevölkerung nach Altersgruppen, Familienstand und Religionszugehörigkeit. 2008,https://www.destatis.de/DE/ZahlenFakten/GesellschaftStaat/Bevoelkerung/Bevoelkerungsstand/Tabellen/AltersgruppenFamilienstand.html.Google Scholar
- The World Bank: PPP conversion factor, GDP (LCU per international $).http://data.worldbank.org/indicator/PA.NUS.PPP.
- Zinsenberechnen.de: Inflationsrechner.http://www.zinsen-berechnen.de/inflationsrechner.php.
- Australian Bureau of Statistics: Australian Historical Population Statistics. 1. Population Size and Growth (cat. no. 3105.0.65.001).http://www.abs.gov.au/AUSSTATS/abs@.nsf/DetailsPage/3105.0.65.0012008?OpenDocument.
- Statistics Canada: Estimated population of Canada. 1605,http://www.statcan.gc.ca/pub/98-187-x/4151287-eng.htm#table%203, to present.Google Scholar
- Population Estimates Program, Population Division, U.S. Census Bureau: Resident population estimates of the united states by Age and Sex, selected years from. 1990,http://www.census.gov/popest/data/national/totals/1990s/tables/nat-agesex.txt, to 2000.Google Scholar
- National Data Archive on Child Abuse and Neglect: Study of National Incidence and Prevalence of Child Abuse and Neglect. 1987, Ithaca: NIS-2Google Scholar
- Beske F, Drabinski T, Golbach U: Leistungskatalog des Gesundheitswesens im internationalen Vergleich. Eine Analyse von 14 Ländern. Institut für Gesundheits-System-Forschung. Edited by: Fritz B. 2005, Kiel: Schmidt & Klaunig, [Fritz Beske Institut für Gesundheits-System-Forschung (Series editor) Schriftenreihe / Institut für Gesundheits-System-Forschung Kiel, vol 104.]Google Scholar
- Statistisches Bundesamt – German Federal Statistical Office: Bruttoinlandsprodukt für Deutschland. 2008,https://www.destatis.de/DE/PresseService/Presse/Pressekonferenzen/2009/BIP2008/Pressebroschuere_BIP2008.pdf?__blob=publicationFile.Google Scholar
- Tress W: Das Rätsel der seelischen Gesundheit. Traumatische Kindheit und früher Schutz gegen psychogene Störungen. 1986, Göttingen: Vandenhoeck & RuprechtGoogle Scholar
- Tagay S, Gunzelmann T, Brähler E: Posttraumatische Belastungsstörungen alter Menschen. Psychotherapie. 2009, 14: 234-342.Google Scholar
- De Bellis MD, Thomas LA: Biologic findings of post-traumatic stress disorder and child maltreatment. Curr Psychiatry Rep. 2003, 5: 108-117. 10.1007/s11920-003-0027-z.View ArticlePubMedGoogle Scholar
- Sachs-Ericsson N, Blazer D, Plant EA, Arnow B: Childhood sexual and physical abuse and the 1-year prevalence of medical problems in the national comorbidity survey. Health Psychol. 2005, 24: 32-40.View ArticlePubMedGoogle Scholar
- Fergusson DM, Lynskey MT, Horwood LJ: Childhood sexual abuse and psychiatric disorder in young adulthood: I. Prevalence of sexual abuse and factors associated with sexual abuse. J Am Acad Child Adolesc Psychiatry. 1996, 34: 1355-1364.View ArticleGoogle Scholar
- Schulte-Markwort M, Bindt C: Psychotherapie im Kindes- und Jugendalter. Psychotherapeut. 2006, 51: 72-79.Google Scholar
- Fegert JM: Kinderschutz aus kinder- und jugendpsychiatrischer und psychotherapeutischer Sicht. Zeitschrift für Kindschaftsrecht und Jugendhilfe. 2008, 4: 136-139.Google Scholar
- Fegert JM, Schnoor K, Kleidt S, Kindler H, Ziegenhain U: Lernen aus problematischen Kinderschutzverläufen - Machbarkeitsexpertise zur Verbesserung des Kinderschutzes durch systematische Fehleranalyse. Bundesministerium für Familie, Senioren, Frauen und Jugend. 2008, Berlin: 2008,http://www.bmfsfj.de/RedaktionBMFSFJ/Broschuerenstelle/Pdf-Anlagen/Lernen-aus-problematischen-Kinderschutzverl_C3_A4ufen,property=pdf,bereich=bmfsfj,sprache=de,rwb=true.pdf.Google Scholar
- Krüger A, Brüggemann A, Holst P, Schulte-Markwort M: Psychisch traumatisierte Kinder: Vernetzung unabdingbar. Dtsch Arztebl. 2006, 103: A2230-A2231.Google Scholar
- Fegert JM, Ziegenhain U, Goldbeck L: Traumatisierte Kinder und Jugendliche in Deutschland. Analysen und Empfehlungen zu Versorgung und Betreuung. 2010, Weinheim, München: Juventa, Fegert JM, Ziegenhain U, Goldbeck L (Series editors): Studien und Praxishilfen zum KinderschutzGoogle Scholar
- Kraft S, Schepker R, Goldbeck L, Fegert JM: Behandlung der posttraumatischen Belastungsstörung bei Kindern und Jugendlichen: Eine Übersicht empirischer Wirksamkeitsstudien. Nervenheilkunde. 2006, 25: 709-716.Google Scholar
- Cierpka M, Streeck-Fischer A: Kinder- und Jugendlichenpsychotherapie in Deutschland. Psychotherapeut. 2006, 51: 71.View ArticleGoogle Scholar
- Fegert JM: Sexueller Missbrauch an Kindern und Jugendlichen. Bundesgesundheitsblatt Gesundheitsforschung Gesundheitsschutz. 2007, 50: 78-89. 10.1007/s00103-007-0111-y.View ArticlePubMedGoogle Scholar
- Fegert JM, Resch F: Editorial. Z Kinder Jugendpsychiatr Psychother. 2009, 37: 91-92.View ArticlePubMedGoogle Scholar
- Corso PS, Lutzker JR: The need for economic analysis in research on child maltreatment. Child Abuse Negl. 2006, 30: 727-738. 10.1016/j.chiabu.2005.12.006.View ArticlePubMedGoogle Scholar
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.