Chiara Massullo,Elena De Rossi,Giuseppe Alessio Carbone,Claudio Imperatori,Rita B. Ardito,Mauro Adenzato,Benedetto Farina
Child Maltreatment, Abuse, and Neglect: An Umbrella Review of Their Prevalence and Definitions
child,adolescents,maltreatment,abuse,neglect,epidemiology,terminology
Objective Child maltreatment (CM) is a recognized public health problem, and epidemiologic data suggest that it is a widespread phenomenon, albeit with widely varying estimates. Indeed, CM as well as child abuse (CA) and neglect (CN) are complex phenomena that are difficult to study for several reasons, including terminological and definitional problems that pose a hurdle to estimating epidemiological rates. Therefore, the main aim of this umbrella review is to revise recent review data on the epidemiology of CM, CA, and CN. A second aim was to revise the definitions used. Method A systematic search of three databases was performed in March 2022. Recent reviews (published in the last 5 years: 2017-March 2022) addressing the epidemiological rates of CM, CA, and/or CN were included. Results Of the 314 documents retrieved by the selected search strategy, the eligibility assessment yielded a total of 29 eligible documents. Because of the great heterogeneity among them, a qualitative rather than a quantitative synthesis was performed. Conclusions The data from this umbrella review show that the different age groups, methods, and instruments used in the literature to collect the data on the epidemiology of CM make it difficult to compare the results. Although definitions appear to be quite homogeneous, CM categorization varies widely across studies. Furthermore, this umbrella review shows that the CM reviews considered do not examine some particular forms of CM such as parental overprotection. The results are discussed in detail throughout the paper.
Child Maltreatment, Abuse, and Neglect: An Umbrella Review of Their Prevalence and Definitions

Child maltreatment (CM) is a recognized public health problem, and epidemiologic data suggest that it is a widespread phenomenon, albeit with widely varying estimates. Indeed, CM as well as child abuse (CA) and neglect (CN) are complex phenomena that are difficult to study for several reasons, including terminological and definitional problems that pose a hurdle to estimating epidemiological rates. Therefore, the main aim of this umbrella review is to revise recent review data on the epidemiology of CM, CA, and CN. A second aim was to revise the definitions used.

A systematic search of three databases was performed in March 2022. Recent reviews (published in the last 5 years: 2017-March 2022) addressing the epidemiological rates of CM, CA, and/or CN were included.

Of the 314 documents retrieved by the selected search strategy, the eligibility assessment yielded a total of 29 eligible documents. Because of the great heterogeneity among them, a qualitative rather than a quantitative synthesis was performed.

The data from this umbrella review show that the different age groups, methods, and instruments used in the literature to collect the data on the epidemiology of CM make it difficult to compare the results. Although definitions appear to be quite homogeneous, CM categorization varies widely across studies. Furthermore, this umbrella review shows that the CM reviews considered do not examine some particular forms of CM such as parental overprotection. The results are discussed in detail throughout the paper.

Child maltreatment (CM) is internationally recognized as a serious public health, human rights, legal, and social problem (World Health Organization, 2006). Epidemiological studies show that CM is extremely common. Approximately one in four children is affected at some point in their lives (Lippard & Nemeroff, 2020). In terms of mental health, the various forms of CM such as child neglect (CN) and child abuse (CA) are considered the strongest predictors of several mental disorders across the lifespan and are associated with 44.6% of disorders occurring in childhood and 25.932.0% of disorders occurring later (Green et al., 2010; Lippard & Nemeroff, 2020; McCrory et al., 2017). They are also a major cause of more severe symptomatology, poor prognosis, and treatment resistance, regardless of the disorder or type of therapy (McCrory et al., 2017; Farina et al., 2019). For these reasons, the study of CM is crucial not only for developmental psychopathology but also for all mental health fields: from clinical psychiatry to psychotherapy and health psychology. In the scientific literature, different forms of CM are described: physical, sexual, emotional /psychological abuse, and neglect (American Psychiatric Association, 2013; World Health Organization, 2006). They can occur individually or, more commonly, in combination (Farina et al., 2019; U.S. Department of Health & Human Services, 2022). However, despite their importance and prevalence, definitions and conceptualizations of CM, neglect, and abuse lack broad agreement among researchers. For example, some authors (e.g., Bernstein et al., 1998) acknowledged phenomena such as child abuse and neglect under the conceptualization of trauma, while some other conceptualizations (as in the case of Centers for Disease and Control Prevention, 2022) included them under the wider category of adverse childhood experiences (ACEs). This leads to wide variability in epidemiologic data, which is in addition to other complex factors such as the different age groups sampled, the different instruments used, and, in general, the survey method (Stoltenborgh et al., 2011; World Health Organization, 2022). Indeed, as reported by Moody et al. (2018, p. 1) “estimating the prevalence of child maltreatment is challenging due to the absence of a clear ‘gold standard’ as to what constitutes maltreatment”. Thus, the aim of this umbrella review (Grant & Booth, 2009) is to provide a comprehensive overview of recent review-data on the epidemiology of the various forms of CM and to consider possible moderators. A further aim is to analyze, summarize, and critically discuss the definitions and conceptualizations used in these recent epidemiologic reviews of CM and its various forms.

The systematic search was conducted on March 28th, 2022, in the Scopus, PubMed, and Web of Science (WoS) databases by combining the following search terms: "child maltreatment" or "child abuse" or "child neglect" and "incidence" or "prevalence" or “epidemiology”. The search strategy for each database is reported in table 1. The search was limited to the last five years (i.e., only publications from 2017 to March 2022 were considered) and to review articles. This time period was chosen to cover the most recent reviews, most of which examine different decades of research on CM, CA, and CN. In this way, we chose to conduct an umbrella review (Grant & Booth, 2009) of the recent literature. A glossary of abbreviations used in the text and tables is provided in table 2 to facilitate reading.

Regarding inclusion criteria, we included documents if they: i) were written in English, ii) were review studies (e.g., narrative reviews, systematic reviews, meta-analyses), iii) primarily, overtly, and conclusively reported incidence or prevalence rates (or ODD ratio values) for CM, and/or CA, and/or CN as a result of their review process. To this regard, we included both retrospective (e.g., those focusing on adult samples in whom CM/CA/CN occurred in childhood) and developmental (i.e., those focusing on CM/CA/CN that occurred or were reported in childhood) review data. In this context, we did not define CM, CA, and CN or their age range in childhood a priori, but we chose to extract and discuss this information. On the other hand, documents were excluded if they: i) were not written in English, ii) were not review articles, iii) addressed other topics (not aimed at reviewing the epidemiology of CM/CA/CN), iv) did not primarily, overtly, and conclusively reported summary/pooled/range data for incidence or prevalence rates (or ODDs ratio) of CM, and/or CA, and/or CN in the main text as a result of the review process. In accordance with exclusion criterion “iii)”, we chose to exclude reviews on non-accidental trauma because the association with CM, CA, and CN is not direct. Similarly, we excluded all studies dealing with bone fractures where the association with such experiences was not direct. However, we did not exclude studies in which such an association is direct by definition such as, for example, those on Shaken Baby Syndrome/Abusive Head Trauma or Traumatic Head Injury due to Child Maltreatment. Inclusion of studies was assessed by two independent raters. In disputed cases, a third rater assessed that record and decided on inclusion. In further cases of doubt, inclusion was discussed by conferencing among the three raters until consensus was reached. The inter-rater agreement between the first two raters was fair (Cohen’s kappa= .23; accordance=75.25%).

The data contained in the included reviews were analyzed and extracted by a trained researcher and independently reviewed by two other trained scholars. In accordance with the aims of the current study, the following data were extracted: author/s, year of publication, type of article, number of studies included in the review, temporal range of the correspondent literature research, CM/CA/CN temporal assessment (retrospectively conducted on adults reporting CM/ CA/CN in childhood or conducted at developmental age and related to ongoing or recent CM/CA/CN), target population, target country (if any), types of CM/ CA/CN considered, macro-category under which they were categorized, epidemiologic rates (these data are presented in table 3). In addition, we also extracted the following definition-related information (table 4): definition of childhood, assessment instruments, types of CM/CA/CN considered (this information overlaps with that previously cited and has been duplicated in tables 3 and 4 for ease of reading), operational definition of CM/CA/CN (according to the inclusion/exclusion criteria of the included review), cited definition/s for CM/CA/CN (if any), and the respective references (if any). With respect to the cited definitions, in this section we decided to include also macro-definitions under which CM/CA/CN (e.g., polyvictimization) was classified. A qualitative synthesis was performed to interpret the results. Due to the heterogeneity of the designs and analysis methods of the reviews included in the current work, no quantitative synthesis was performed.

In total, the systematic search yielded 314 studies (n= 209 on Scopus, n= 57 on PubMed, and n= 48 on WoS). Of these, n= 65 records were excluded because they were duplicates. Thus, n= 249 studies were screened for eligibility. Title and abstract screening excluded a total of n=26 documents. Of these, n=13 were excluded because they were not in English, n=10 because they were not review articles, n=3 because they concerned other topics. Thus, n=223 full texts were sought for retrieval and n=1 document was not found. Thus, n=222 documents were assessed for eligibility. Of these, n=2 were excluded because they were not in English, n=23 because they were not review articles, n=108 because they addressed a different topic, and n=60 because epidemiologic data for CM/CA/CN were not primarily reported or were not specifically, overtly, and conclusively reported in terms of range values/ pooled data/ODDs ratio. Thus, 29 documents were considered eligible for the current umbrella review. The PRISMA (Page et al., 2021) flow diagram of included reviews is shown in figure 1. Of the included reviews, n=11 related to retrospective data (generally on adults), n=9 related to developmental age (of which n=1 review focused on developmental age, but the authors described the included studies as retrospective), n=1 review was prospective (i.e., considers Neonatal Abstinence Syndrome (NAS) as a risk factor preceding CM), n=1 review considered both retrospective and prospective data (i.e., longitudinal studies), n=1 review considered both developmental-age individuals (i.e., high school students) and adults, n=2 did not specify, and the remaining n=3 considered mixed research designs. Furthermore, n=1 study addresses the presentation of the WHO Violence Prevention Information System, an interactive knowledge platform that contains scientific data on violence and specifically on CM, CA, and CN. The data available on this platform are based on different data sources and, according to our inclusion/ exclusion criteria, we report only the data based on a review-like methodology (i.e., merged data coming from different studies, specifically, from a number ≥ 5 studies). Regarding the target country, the above-mentioned search provides country-specific review data for all countries in the world for which such data are available (see table 3 for more details). In addition, of the included studies, n=3 were worldwide meta-analyses, n=12 were reviews conducted at country level or targeted a specific geographic area [i.e., Latin American and Caribbean countries, Maghreb, Japan (n=2), China (n=3), Canada, India, Indonesia, South Asian countries], n=1 focused on low- and lower middle-income countries, and the remaining n=12 systematic reviews or meta-analyses were conducted without considering a geographic/political criterion. Regarding the type of CM/CA/CN reviewed, results revealed that n=6 studies focused only on Child Sexual Abuse (CSA) [also called Child Sexual Violence (CSV)], n=12 addressed both Child Physical Abuse (CPA), Child Emotional Abuse (CEA)/Child Psychological Abuse (CPA), CN [Child Neglect; expressed in terms of Child Emotional Neglect (CEN) and Child Physical Neglect (CPN), or CN only], and CSA. Other review studies were conducted on mixed forms of victimization, specifically, n=1 on Child Physical Maltreatment (CPM), Child Emotional Maltreatment (CEM)/Child Psychological Maltreatment (CPM), Child Sexual Maltreatment (CSM), CN, and financial exploitation, forced work, over burden, witness/ indirect victimization; n=1 on CEA, CEN and exposure to Intimate Partner Violence (IPV); n=1 on CSA, CPA, CEA, CEN, CPN and domestic violence, parental offending and other forms of victimization; n=1 on CSA, CPA, CEM, CN and exposure to IPV; n=1 on CPM, CPS, CEM, CN and witnessing violent acts, experiencing being robbed, having personal properties vandalized, and abduction; n=1 on exposure to violence by youths which included Physical Violence (PV), Emotional Violence (EV), and Sexual Abuse (SA); n=1 on PV, EV by caregivers, by students, and on physical IPV. In addition, n=1 addressed CM in general, n=1 addressed the Shaken Baby Syndrome/Abusive Head Trauma, and n=2 focused on CN only (one on CPN and CEN, and the other on CPN, CEN, educational, security and medical neglect). Heterogeneity in terminology and definitions used is described in more detail in a dedicated section. A detailed description of the above reported information for the included reviews as well as for the other extracted – but here not mentioned – can be found in table 3.

This section provides an overview of CM, CA, and the definitions used in the reviews considered. The results show heterogeneity in the definitions cited. Detailed information is provided below, and full data on these are presented in table 4. Of the reviews considered, a large proportion cites the World Health Organization (WHO) definition. In this definition, CM is a macro-category that includes both CA and CN. Some of these studies added other citations to the WHO definition, such as in the review by Ahad et al. (2021), who also cited Amdi (1990); National Research Council (1993); and Rutherford et al. (2007). However, in studies citing the WHO for the CM definition, some differences can be found in the WHO citation, such as the document (e.g., Krug et al., 2002a; World Health Organization, 1999) or the online resource cited [e.g., the definition reported on the WHO online website visited at different time points (e.g., World Health Organization, 2015; World Health Organization, 2016a, 2019)], but also the way in which the definitions are reported. In this context, Zhang et al. (2020), for example, do not quote the World Health Organization (2016a) verbatim, and report that CM “involves repeated trauma (…)” (Zhang et al., 2020; p. 1). This aspect differs from the ongoing WHO definition which can be found on the World Health Organization (2022) website [or that reported in World Health Organization (1999)]. However, the other studies chose different citations or approaches: some of them cited definitions reported in previous studies and others cited those reported by a specific institutional consortium (e.g., Centers for Disease Control and Prevention, 2019; Public Health Agency of Canada, 2010). For example, Wang et al. (2020) and Fu (2018) reported citations of CM from CDC (Centers for Disease Control and Prevention, 2017; 2019, respectively), that were quite similar to those reported by WHO (see table 2 for more details). In addition, one study overlapped the concepts of CA and CM and offered a cumulative definition for them, generally citing WHO. Furthermore, Tanaka et al. (2017), whose work focused on CSA, reported it as a subtype of CM (i.e., “CSA, as well as other subtypes of child maltreatment”; p. 32). On the other hand, some authors have classified the experiences of CA and CN (and often their subtypes CEA, CPA, CSA, CEN/CPSN, CPN) into macro-categories other than CM, such as “childhood adversities” and “childhood trauma”. For example, in the study by Peh et al. (2019), CA and CN are defined under the macro-category CT (and not CM), which in turn is defined under the macro-category “childhood adversities”. Furthermore, in the review by Kimber et al. (2017), the authors report that research on CM suggests that CEA and CEN are two different forms of CA, as the former is an act of commission and the latter is an act of omission. Apart from the classification of the act based on the agency, it can be stated in this definition that CEA and CEN fall under the category CA, which in turn is considered under the broader category CM. In doing so, the authors refer to the definition of Caslini et al. (2016), while for the definition of CM they refer to that of Gilbert et al. (2009) which, unlike other defintions such as the ones citing the WHO, includes children’s exposure to IPV as a form of CM. In addition, in the Malvaso et al. (2021) study, the authors referred to the term ACEs by Felitti et al. (1998) to indicate “the cumulative effects of both maltreatment (physical, sexual and emotional abuse, and physical and emotional neglect) and household dysfunction (parental separation, domestic violence, mental illness, substance abuse, and incarceration) before the age of 18” (as reported in Malvaso et al., 2021; p. 1). According to this definition, ACEs represent a macro-category that includes the cumulative effects of household dysfunction and CM which, in turn, include both CA and CN. In contrast, some other definitions adopted by authors group CM under the broad categories of “victimization” and “polyvictimization” (i.e., Hellström, 2019; Le et al., 2018). Other studies focused on sexual victimization/ abuse/violence against children. Again, the included reviews show definitional inconsistencies. Indeed, as openly reported by Karlsson and Zielinski (2020; p. 327): “Operationalizing sexual victimization, on the other hand, is more challenging as there is no universal definition of sexual violence or sexual assault”. Indeed, the majority of studies define the term as CSA, but the terms CSV and Teen Sexual Abuse have also been adopted by some other authors. In addition, n=2 studies (Pignatelli et al., 2017; Zhang et al., 2021) addressed CN only and provided different definitions, although both included the WHO’s citation. Furthermore, n=1 study (Biswas & Shroff, 2021) addressed a specific form of abuse, namely Shaken Baby Syndrome/Abusive Head Trauma. Again did not report a specific definition, some other included reviews. More detailed information for each included review is provided in table 4.

Regarding the operationalization of CM, CA, and CN, the included studies also showed variability in this regard. Specifically, a large proportion of the reviews defined childhood as before age 18 (i.e., 0-18 years old), whereas some other studies operationalized developmental age as 0-19 years old, and still others defined youths as between 13 and 24 years old. In addition, some operationalizations considered only CSA, while others considered both CSA, CEA, and CEN and CPSN. Others defined these categories in the context of maltreatment rather than abuse, such as the study by Ahad et al. (2021), which included Child Physical Maltreatment (CPM) – rather than CSA –, Child Emotional/Psychological Maltreatment (CE/PSM) – rather than CEA/CPSA -, Child Sexual Maltreatment (CSM) – rather than CSA. Another example is the study by Devries et al. (2019), which considered PV and EV (perpetrated by different actors) instead of CPA and CEA or CPM or CEM. Again, some studies categorize CSA, CPA, CEA, CN under the definition of ACEs (Malvaso et al., 2021), while other studies categorize them as CM (Laurin et al., 2018). Full data on operationalizations as well as on assessment materials are presented in table 4.

In a world-wide meta-analysis on the prevalence of CSA in women (Pan et al., 2021), the authors used the Childhood Trauma Questionnaire (CTQ) as an outcome measure. The results showed that the overall pooled rate of CSA was 24%. They also reported that the rate of CSA was higher in females compared with the general group in people with mental illness. In this regard, it should be noted that this result varied by geographic region. Indeed, in the study by Moody et al. (2018), which aimed to estimate worldwide prevalence rates considering self-report studies on maltreatment, the results showed that the median prevalence of CSA among girls was 20.4% in North America and 28.8% in Australia. For boys, results showed that they generally had lower rates. Regarding CPA, rates were similar between the sexes, except in Europe, where they were 12% for girls and 27% for boys. In other countries (e.g., in Africa), CPA rates appear to be very high (e.g., 50.8% and 60.2% for African girls and boys, respectively). Regarding median rates of emotional abuse, they appear to be almost twice as high for girls as for boys in both North America (28.4% and 13.8%, respectively) and Europe (12.9% and 6.2%, respectively). However, in other countries, they appear to be more similar in girls and boys. Although few studies were available for CN, median rates were high in Africa and South America (girls: 41.8%, boys: 39.1% for the first continent; girls: 54.8%, boys: 56.7% for the second continent). On the other hand, when considering North America and Asia (i.e., the continents with the highest number of available studies) CN median rates differ between girls and boys for the first continent (40.5% and 16.6%, respectively), whereas they are similar for Asia (girls: 26.3%, boys: 23.8%). The review by Biswas and Shroff (2021) also looked at worldwide data but, unlike the other studies, focused on a specific form of abuse: the Shaken Baby Syndrome/Abusive Head Trauma. The results showed that global rates for this form of abuse are unknown. Incidence rates from the available population studies (i.e., Switzerland, New Zealand, Wales, Scotland, Queensland – Australia, USA, Canada) ranged from 14 to 53 per 100,000 live births. Epidemiologic data from the included studies are shown in table 3.

Among the review studies that focused on a national – or, generally, on a specific – context, Choudhry et al. (2018) conducted a systematic review that focused on CSA in the Indian context and considered literature published from 2006 to 2016. The results showed that CSA prevalence went from 4% to 41% among girls under 18 years of age, and among those who exceeded this age window lifetime CSA-P went from 3% to 39%. Among boys in educational institutions, CSA-P went from 4% to 75%. Furthermore, Fu (2018) conducted a systematic-review and meta-analytic study in the Chinese context, considering studies published in a time window that overlapped with the above study (from 2006 to 2017). Specifically, the authors aimed to estimate CM prevalence among college students. The results showed that the CM pooled prevalence among college students was 64.7%. Specifically, the pooled estimates for CPA, CEA, CSA, CPN, and CEN were 17.4%, 36.7%, 15.7%, 54.9%, and 60%, respectively. Even in the Chinese context, in another review (i.e., specifically a systematic review and meta-analytic study) (Wang et al., 2020), the authors considered studies up to 2019 that addressed CPA, CEA, CSA, CPN, and CEN in Chinese primary school and middle school students. They found that the pooled prevalence was 0.20% for CPA, 0.30% for CEA, 0.12% for CSA, 0.47% for CPN, and 0.44% for CEN. Of note, CEN was reported primarily in rural areas. In addition, CPN and CEN were higher in studies conducted in the northern part of the Country than in southern and central China. The results also showed that children with mental health symptoms (compared with children without them) had a higher incidence for all CM categories. In another study conducted in the Chinese context (Zhang et al., 2021), the authors meta-analyzed studies up to 2019 (April) on CN in 3-6-year-old children in China. The results showed that the PP for CN was 32.1%, while for CN subtypes it was as follows: CPN=15.2%, CEN=15.2%, educational CN=10.4%, security CN=13.8%, and medical CN=11.5%. In the Japanese context, two review studies have been conducted (Mo et al., 2020; Tanaka et al., 2017). In the systematic review by Mo et al. (2020), the results based on studies from 2010 to 2018 yielded the following estimates for the following types of CA and CN. In males, CPA-prevalence was 8.40% and CPA incidence was 1.50%. In females, they were 6.69% and 1.19%, respectively. In males, CSA prevalence was 0.33% and the incidence was 0.11 %; in females, the prevalence was 7.38% and the incidence was 2.54%. The prevalence of Child Psychological Abuse (CPSA) associated with witnessing domestic violence (WDV) was 9.94% and the incidence was 2.16% for males. For females, the prevalence and incidence were 16.75% and 3.64%, respectively. For other forms of CPSA, the prevalence was 5.64% and the incidence was 1.23% for males. In females, the prevalence was 5.95% and the incidence was 1.29%. For CN, the prevalence and the incidence in males were 8.89% and 1.93%, respectively. In females, they were 9.01% and 1.96%, respectively. In the other systematic review conducted in the Japanese context (Tanaka et al., 2017), the authors focused on CSA studies conducted in non-clinical samples that included both individuals younger than 18 years and adults. The results showed that the prevalence of physical contact (not involving penetration)-CSA ranged from 10.4% to 60.7% in females and was 4.1% in males. On the other hand, the prevalence of penetrative-CSA went from 1.3% to 8.3% in females, and from 0.5% to 1.3% in males. Regarding South Asian countries in general, the scoping review by Ahad et al. (2021) examined studies from 1960 to 2020 that estimated the epidemiology of child laborers’ CPM, CE/PM, CSM, CN, financial exploitation, forced work, over burden, witness/indirect victimization. The results showed the following prevalence values: CPM=15.14%, CE/PM=52.21%, CSM=16.82%, CN=12.9%, financial exploitation=2.2%, forced work=1.7%, over burden= 3%, witness/indirect victimization= 94.46%. Another review (Mlouki et al., 2020) focused on studies that addressed exposure to violence among youths - including exposure to PV, EV, and SA - in Maghreb countries. They considered studies on youths conducted up to 2019 (October). The results showed that CPA-P was the most common type of violence, accounting for 43.8%. In addition, male adolescents were found to be most frequently affected by PV, while females were more likely to experience EV (63% vs. 51%). Another systematic review (Devries et al., 2019) focused on estimating the prevalence of recent PV, SV, and EV among 0-19-year-olds in Latin America and the Caribbean countries using studies and surveys up to 2015. The results showed that the prevalence of PV-and EV among caregivers ranged from 30% to 60% and decreased with age. In addition, PV prevalence among students ranged from 17% to 61% and decreased with age, which was different from EV prevalence, which was found to be constant. The prevalence of EV ranged from 60% to 92%, while the prevalence of physical IPV ranged from 13% to 18% among 15-19-year-old females. Data from Canada came from a systematic review and meta-analysis of CSA, CPA, CEA, and CN among Canadian incarcerated population (Bodkin et al., 2019). Results showed that the summary prevalence for each type of CA was 65.7% in women; only one of the studies reviewed by the authors reported prevalence in men (35.5%). The summary prevalence of CSA was 50.4% in women and 21.9% in men. The prevalence of CN was 51.5% in women and 42.0% in men. The prevalence of CPA was 47.7%, and the prevalence of CEA was 51.5%. Of the included reviews, the one by Karlsson and Zielinski (2020) was conducted in the United States. Specifically, the authors retrospectively examined CSA and Teen Sexual Abuse (TSA) in studies conducted on incarcerated women up to 2017 (August). The results showed that the best estimates for CSA from studies that used validated survey methods ranged from 50% to 66% and that lifetime sexual violence ranged from 56% to 82%. For TSA, the authors found a limited number of studies that did not allow summation of estimates. In addition, the systematic review and meta-analysis by Le et al. (2018) focused on data on victimization among children and adolescents from low- and lower-middle-income countries. They examined diferent forms of victimization, including CPS, CEM, CN, witnessing violent acts, experiencing being robbed, having personal property vandalized, and abduction. Results showed that the pooled prevalence of experiencing any type of victimization was 76.8%, while the overall prevalence estimate for polyvictimization was 38.1%. Another study that considers country-level data is the WHO’s Violence Info platform presentation by Burrows et al. (2018). For it, we only consider data based on a review-like methodology (i.e., merged data from a number ≥ 5 studies). Several country-level data were available (see table 3) but, as stated on their website (https://apps.who.int/violence-info/child-maltreatment), “these do not represent national or regional prevalence estimates” but “the median value in the range of lifetime prevalence estimates reported by studies in the database”.

Among reviews that did not address a specific geographic/political context (i.e., did not overtly aim to estimate epidemic rates worldwide or at a national/ specific level), a recent review by Brunton and Dryer (2021) focused on the prevalence of CSA and its associated outcomes during pregnancy and childbirth. The results showed that the prevalence of CSA in pregnant women ranged from 2.63% to 37.25%. Notably, the authors found that prevalence rates were often higher or lower depending on certain aspects (e.g., low income for higher rates and higher education for lower). In addition, pregnant women with a history of CSA (compared with women without such a history) are often more concerned about their care and childbirth, have more health-related complaints, dificulty giving birth, and are more likely to have psychiatric symptoms, poor health and sleep, and appearance related concerns. They may also use harmful substances and have a higher risk of being re-victimized. A meta-analysis by Zhang et al. (2020) aimed at estimating the prevalence of Childhood Trauma (measured by the CTQ short form) among people with substance use disorders. CT subtypes prevalence among all samples of people with substance use disorder considered was 38% for CEA; 36% for CPA; 31% for CSA; 31% for CEN and 32% for CPN. Of note, the highest prevalence rates for emotional abuse were found in North America and South America (45%). Furthermore, prevalence rates were highest in North America (compared to other continents) for CPA and CSA, CEN, and CPN (39%-44%). In the systematic review by Paine et al. (2019), the authors examined the prevalence of abuse in children with rib fractures. Results showed that CA prevalence rates varied by age group considered. Indeed, the CA prevalence i) ranged from 67% to 82% in infants younger than 12 months, ii) was of 29% in infants aged 12 to 23 months, and iii) was of 28% in infants aged 24 to 35 months. Accordingly, the authors reported that age younger than 12 months was highly associated with an increased likelihood of abuse across studies (i.e., “the only characteristic significantly associated”, Paine et al., p. 1). In contrast, location of rib fracture was not associated. Another review (Hellström, 2019) addressed polyvictimization in children with Autism Spectrum Disorder (ASD) or Attention Deficit Hyperactivity Disorder (ADHD). The results showed that the prevalence rates for polyvictimization were 1.8% and 23.1% in children with ASD and 7.3% in children with ADHD. In the work of Malvaso et al. (2021), which reviewed the literature from 2000 to 2019, studies retrospectively examined CSA, CPA, CEA, CEN, CPN, domestic violence, parental ofending, and other types of Adverse Childhood Experiences (ACEs) among justice-involved (JI) youth. Results showed that compared with not justice involved (NJI) youth, for JI ones the odds of experiencing at least one ACE were over 12 times greater. The prevalence of CSA among JI youth was 12.2%. The pooled prevalence of JI youth who reported experiencing CPA was 27.4%. The pooled prevalence of JI youth who reported experiencing CEA was 34.2%. The pooled prevalence of parental ofending was 60.8%. The pooled prevalence of JI youth who reported experiencing DV was 55.3%. In the study by Laurin et al. (2018), the authors reviewed literature from 2000 to 2016 –including post-1999 data – on CM among youth. Specifically, they examined CSA, CPA, CEM, CN, and exposure to IPV. Results showed that summary estimates for lifetime P ranged from 0.3% to 44.3% for CSA, 4.2% to 58.3% for CPA, 3.1% to 78.3% for CEM, 0.9% to 38.3% for CN, and 0.6% to 30.9% for IPV exposure. Nelson et al. (2017) conducted a meta-analysis of the literature up to 2013 (November 21st) on individuals with depression and CSA, CPA, CEA, CEN, and CPN. The results showed that the P estimates for individuals with depression were as follows: CSA=25.27%, CPA= 27.59%, CEA= 36.72%, CEN= 43.20%, CPN= 36.18%, any type of CM= 45.59%, multiple forms of CM= 19.13%. In contrast, Prangnell et al. (2020) conducted a systematic review of studies on adult participants with injection drug use and CSA, CEA, and CPA (they did not consider neglect). Results showed that the prevalence of CSA among individuals with injection drug use ranged from 1.4% to 42%; the prevalence of CEA was reported in two studies: 2.3% and 49.6%; and the reported prevalence of CPA ranged from 1.9% to 49.5%. In the systematic review and meta-analysis by Pignatelli et al. (2017), the authors reviewed literature studies on CN – CPN and CEN – in people with eating disorders conducted up to 2015 (July). Results showed that among individuals with eating disorders, the prevalence of CEN was 53.3% and of CPN was 45.4%. Kimber et al. (2017) also reviewed the literature up to 2015 (October 26th) on CEA and CEN in people with eating disorders or eating disordered behaviors. However, unlike Pignatelli et al. (2017), they also considered exposure to IPV and their study was a critical review. The results showed that the prevalence of CEA and CEN ranged from 21.1% to 66.0% in individuals with bulimia nervosa, binge eating disorder, and binge-eating symptoms but no data were available on the prevalence of IPV exposure in children. In addition, Peh et al. (2019) conducted a systematic review and meta-analysis of the literature published up to 2018 (September 25th) on CEA, CPA, CEN, CPN, and CSA in individuals at Ultra-High Risk (UHR) for psychosis and controls. They considered both retrospective and prospective (longitudinal) studies. Overall, the prevalence of CEA, CPA, CEN, CPN, CSA ranged from 54% to 90%. People with UHR were 5.06 times more likely to report CEA and 3.19 times more likely to report CPA. In conclusion, Rees et al. (2020) systematically reviewed and meta-analyzed studies from 1975 to 2019 on CM in people who had Neonatal Abstinence Syndrome. Results showed that CM odds ratio was 13.96 higher in people with NAS than in people without NAS. The authors also found a strong association of NAS with later CM (aOR: 6.49) and with poisoning and injury (aOR: 1.34).

The purpose of this umbrella review was twofold: first, to provide a comprehensive overview of the epidemiological data on CM and its various forms, including potential moderators, and second, to concisely analyze and critically discuss the definitions used in considered review studies. The great heterogeneity among the included reviews did not allow us to perform a quantitative analysis of the epidemiological data and moderators. A qualitative synthesis was performed.

A large proportion of researchers have used the definition of WHO, which distinguishes four different forms of CM: child emotional abuse, child physical abuse, child sexual abuse and neglect. Another widely used classification system is that of the Centers of Disease Control and Prevention of the U.S. Department of Health and Human Services (US-CDC), which does not differ substantially from the definitions of WHO either in distinguishing the different forms of CM or in their definitions (see table 5). This fourfold classification overlaps with that of the DSM-5 (American Psychiatric Association, 2013). It is important to note that both WHO and US-CDC definitions always imply the interpersonal aspect of maltreatment and negative actions directed against the child. Some authors suggest distinguishing between CEA and CEN based on the perpetrator’s actions, as the former is an act of commission and the latter is an act of omission (Kimber et al., 2017). This is consistent with the classification of child abuse and neglect based on the agency used by CDC in Leeb et al. (2008), which also defines CM as: “any act or series of acts of commission or omission by a parent or other caregiver that results in harm, potential for harm, or threat of harm to a child” (Leeb et al., 2008, p. 11). Not all studies derived the definition from the same WHO documents/online resources, and not all studies reproduced the definition verbatim. This means that some studies have used slightly different definitions that include other concepts related to CM experiences. For example, as in the case of Zhang et al. (2020), who reported that CM “involves repeated trauma (…)” (Zhang et al., 2020; p. 1). Some other studies used definitions from local government agencies (Centers for Disease Control and Prevention, 2019; Public Health Agency of Canada, 2010) that are broadly consistent with those from WHO (see Tables 2 and 3 for more details). A problematic element of the definition of CM is the introduction of the concept of childhood trauma (CT) in some studies, as it is generally not clearly described. In fact, the definition of CT itself has the same difficulties as “maltreatment” or “abuse” due to the same wide variance in interpretation and meaning (Isobel & Edwards, 2017). Although CM and CT share many similarities and, in some cases, overlap because they are considered macro-categories that encompass the same subcategories as abuse and neglect (Peh et al., 2019), some differences appear to emerge from their comparison. In fact, an analysis of their descriptions in the scientific literature shows that CT is characterized by more severe, persistent, or repeated threatening events and conditions that cannot be escaped, so the element of inescapability seems to be added (Farina et al., 2019; Isobel & Edwards, 2017). Several reviews focus only on sexual abuse (e.g., Brunton & Dryer, 2021; Choudhry et al., 2018; Karlsson & Zielinski, 2020), although there is considerable overlap between the various descriptions in many cases. Again, researchers complain about a lack of homogeneity in the constructs used (Karlsson and Zielinski, 2020) (see table 4). However, the problem of heterogeneity of definitions occurs mainly in those studies that use concepts other than the CM definition of WHO or similar ones. This is the case, for example, in studies based on the concept of “childhood adversities”. This concept was derived from the definition of Adverse Childhood Experiences (ACEs) by Felitti and colleagues (1998) and adopted by U.S. government agencies. The definition of ACEs is a broader category that includes not only CM, but also adverse events or conditions that are not directed at the child, such as parental separation, witnessing domestic violence, parental mental illness or substance abuse, and incarceration. In some cases, other categories were used that are even broader than ACEs (polyvictimization; Lee et al., 2018), which include not only household dysfunction but also violence one may experience at school or in the community in which one lives. In summary, the heterogeneity of definitions is not so much a problem for defining specific types of maltreatment that are essentially the same, but rather by the breadth of categories used: from those such as CM and its various forms (CPA, CEA, CSA, CN) that focus on acts or omissions directed against children, to broader ones that include household dysfunction and any form of violence or environmental victimization. Finally, this umbrella review shows that the CM reviews considered do not examine some particular forms of CM such as parental overprotection (Farina et al., 2021).

An important point is that, apart from the definitions given in the text of the research papers, whether they are single studies or reviews, the actual phenomenon studied is essentially determined by the instruments used to collect the data. Indeed, in the review studies, a great deal of heterogeneity is evident between the instruments used in the included primary studies to investigate CM, CA, and CN. This heterogeneity occurs both within reviews (i.e., between the primary studies of the reviews) and between reviews (i.e., between the primary studies of one review compared with the others). Indeed, in a large proportion of the included reviews, the inclusion criteria did not provide for the inclusion of primary studies based on a particular assessment instrument. Thus, among these instruments, there are some based on trauma, such as the Childhood Trauma Questionnaire (CTQ); some others based on the concept of victimization, such as the Juvenile Victimization Questionnaire (JVQ); still others based on the ACEs questionnaire. The results of these reviews, which do not consider an inclusion criterion based on an assessment instrument, indicate a large heterogeneity in the operationalization of CM, CA, and CN. However, a small proportion of reviews (i.e., Pan et al., 2021; Zhang et al., 2020) considered the use of a specific assessment tool as an inclusion criterion. In addition, some reviews did not specify assessment instruments. For more information on the instruments used in the primary studies of the included reviews, see table 4. Another problem with the heterogeneity of research data on CM or ACEs lies partly in the differences in the age groups considered and partly in the fact that many studies focus only on specific forms (as in the case of sexual abuse), making it difficult to compare the data with other studies (see table 4).

Comparison of the data collected in the various selected reviews, and presented in table 3, is very difficult due to the heterogeneity of the populations studied, the data collection methods, and the definitions just described. Moreover, it is important to note that epidemiological studies report prevalence but not incidence, with few exceptions (Biswas & Shroff, 2021; Mo et al., 2020). Nevertheless, there are some elements worth reflecting on. In general, females appear to be more affected by CSA than males (Bodkin et al., 2019; Mo et al., 2020; Tanaka et al., 2017). Furthermore, the prevalence of all forms of CM appears to be higher in clinical samples, incarcerated individuals, and juveniles in correctional settings than in the general population. This is consistent with findings widely reported in the scientific literature indicating CM as a risk factor for psychopathology and social dysfunction (Green et al., 2010; Lippard & Nemeroff, 2020; McCrory et al., 2017). Furthermore, as suggested by some national institutions’ data (U.S. Department of Health & Human Services, 2022) on neglect, CN (both CEN and CPN when studied) can have very high prevalence rates, notwithstanding the inherent detection and reporting problems (Fu, 2018; Wang et al., 2020). Moreover, it is important to note that US-CDC epidemiological data indicate that the vast majority of CM (approximately 90%) are perpetrated by parents (U.S. Department of Health & Human Services, 2022).

The data from this umbrella review confirm what other authors have complained, namely that the lack of uniform methods makes it difficult to compare data from different CM studies. Mainly because some studies do not only consider forms of CM but also extend their observations to other negative events or conditions that are not necessarily directed against the child or violence outside the family. On the other hand, when research focuses on forms of CM, definitions seem to be quite homogeneous. It is important to consider another element that seems very important for understanding the different forms of child abuse and neglect. Namely, one of the constituent elements of the definition of abuse and neglect that distinguishes it from other forms of ACEs (such as poverty, war scenarios, or bullying at school) is the role of parents or other caregivers as perpetrators, which is confirmed by epidemiological studies. For example, the US-CDC reports that these phenomena include “all types of abuse and neglect of a child under the age of 18 by a parent, caregiver, or another person in a custodial role (such as a religious leader, a coach, a teacher) that results in harm, the potential for harm, or threat of harm to a child” (Centers for Disease and Control Prevention, 2022). Similarly, the DSM-5 definitions specify that abuse and neglect are perpetrated by a parent, caregiver, or other individual who has responsibility for the child (American Psychiatric Association, 2013). This element is also central to the first drafted WHO definitions (Krug et al., 2002a; World Health Organization, 1999). The WHO Consultation on Child Abuse Prevention formulated the first definition of child abuse and neglect as follows: “Child abuse or maltreatment constitutes all forms of physical and/or emotional ill-treatment, sexual abuse, neglect or negligent treatment or commercial or other exploitation, resulting in actual or potential harm to the child’s health, survival, development or dignity in the context of a relationship of responsibility, trust or power” (World Health Organization, 1999, p. 15). Furthermore, in the chapter on abuse and neglect by parents or other caregivers of the WHO Report on Violence and Health, the authors (Krug, 2002, Chapter 3) defined the four forms of abuse and neglect (described in detail in this umbrella review, i.e., physical abuse, sexual abuse, emotional abuse, and neglect) by caregivers and emphasized that they result from "acts of commission and omission by parents or caregivers that result in harm to the child" (Krug et al., 2002a, p. 59). We should not forget that childhood is a state in which the individual is totally dependent on parents. According to evolutionary and developmental psychology, humans (like all mammals and some other species) have an innate tendency to look for proximity, care, help, and comfort from the caregivers to fulfill many essential purposes, not only for survival (such as defense from danger or nutrition), but also for healthy physiological and socioemotional development (Bowlby, 1969/1982. Harlow & Zimmermann, 1959; Lorenz, 1949). Thus, childhood could be an intrinsic state of vulnerability when caregivers not only actively abuse or threaten, but also neglect and abdicate their caregiving and regulatory roles (Isobel & Edwards, 2017; Liotti, 2004). Even a cognitive, affective, and neurovegetative misattunement with a hyper-aroused and dysregulated caregiver represents a pervasive stressor that can lead to lasting changes in neural, emotional, cognitive, and social development (Adenzato et al., 2019; Cicerale et al., 2013; Guérin-Marion et al., 2020; Massullo et al., 2022). For all of these reasons, parental neglect, understood as deprivation “of a stable, sensitive, and responsive caregiver, which is a species-expectant experience” (McLaughlin et al., 2017; p. 463), is the most important and common form of CM. Furthermore, previous research by Bifulco and Schimmenti (2019) suggested that forms of CM tend to be associated each other, with failures of care such as neglect having a strong association with episodes of sexual abuse. In other words, we hypothesize that neglect is at the root of all forms of CM because an actively abusive parent (physically, emotionally, and sexually) is simultaneously a caregiver who is not fulfilling his/her evolutionarily predisposed role. In addition, when violence or abuse is perpetrated outside the family, consideration should be given to whether the negative events were caused or encouraged by an absent or otherwise unprotective parent. We also believe that underlying the various forms of childhood maltreatment (including little-studied forms such as parental overprotection) may be the role of attachment trauma, understood as a severe and persistent failure of caregivers to perform a protective and regulatory role (Isobel & Edwards, 2017). A caregiver who neglects or actively abuses is indeed a traumatic condition, because he/she, who should be the primary source of safety and care, is at the same moment the source of an active or passive threat that leads to an unbearable and inescapable threatening one-time or ongoing experience that the child is powerless to face (Farina et al., 2019).

Although the results and conclusions of this umbrella review are potentially interesting, they should be considered with some limitations. In particular, the methodology adopted in this work means that we did not consider all the published literature on epidemiology and, consequently, on the definitions of CM, CA, and CN. Although the partial selection of literature made in our work may provide a basis for discussing the widely known problem in the literature of difficulties in estimating the epidemiology of CM, CA, and CN, which are also related to definitional inconsistencies, on the other hand, we lack a part of the literature that would have enriched and deepened the results and discussion. Accordingly, we report and discuss the results in a qualitative manner only. Future studies should cover a broader corpus of studies, also based on a larger time window.