The Long-Term Health Consequences of Child Physical Abuse, Emotional Abuse, and Neglect: A Systematic Review and Meta-Analysis

The Long-Term Health Consequences of Child Physical Abuse, Emotional Abuse, and Neglect: A Systematic Review and Meta-Analysis

The Long-Term Health Consequences of Child Physical Abuse, Emotional Abuse, and Neglect: A Systematic Review and Meta-Analysis

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Child maltreatment is defined as all forms of physical and/or

emotional ill-treatment, sexual abuse, neglect or negligent treat-

ment, or commercial or other exploitation of children that results in

actual or potential harm to a child’s health, survival, development,

or dignity in the context of a relationship of responsibility, trust, or

power [1]. Four types of maltreatment are commonly recognised:

sexual abuse, physical abuse, emotional abuse (also referred to as

psychological abuse), and neglect (Table 1).

There is a great deal of uncertainty around estimates of the

frequency and severity of child maltreatment worldwide.

Furthermore, much violence against children remains largely

hidden and unreported because of fear and stigma and the

societal acceptance of this type of violence [2]. Globally,

prevalence of reported child sexual abuse varies from 2% to

62%, with some of this variation explained by a number of

methodological factors including definition of abuse, method of

data collection, and type of sample assessed [3]. In high-income

countries, the annual prevalence of physical abuse ranges from

4% to 16%, and approximately 10% of children are neglected

or emotionally abused [4]. Eighty percent of this maltreatment

is perpetrated by parents or parental guardians [4], and poverty,

mental health problems, low educational achievement, alcohol

and drug misuse, having been maltreated oneself as a child, and

family breakdown or violence between other family members

are all important risk factors for parents abusing their children

[5].

There is growing recognition that different forms of interper-

sonal violence have a large public health impact [6]. In children,

the consequences of violence can vary widely. Physical injuries

and, in extreme cases, death are direct consequences. World

Health Organization (WHO) estimates of child homicide suggest

that infants and very young children are at greatest risk, with rates

for the 0- to 4-y age group about double those for 5- to 14-y-olds as

a result of their dependency and vulnerability [5]. However, in the

majority of non-fatal cases, the direct physical injury causes less

morbidity to the child than the long-term impact of the violence

on the child’s neurological, cognitive, and emotional development

and overall health [5].

Child maltreatment is a major public health problem, yet a lack

of understanding of its serious lifelong consequences and of the

cost and burden on society has hampered investment in

prevention policies and programs. In order to effectively respond

to the problem, the WHO 2006 report on prevention of child

maltreatment [5] recommended expanding the scientific evidence

base for the magnitude, consequences, and preventability of child

maltreatment.

The relationship between child sexual abuse and adverse

psychological consequences in adults is well established [7–9],

and in the WHO comparative risk assessment study, Andrews and

colleagues [3] carried out a systematic review and meta-analysis

summarising the evidence of a relationship between child sexual

abuse and subsequent mental disorders. This review is currently

being updated in the new iteration of the Global Burden of

Diseases, Injuries, and Risk Factors Study, aiming to provide

global estimates of attributable burden for 1990 to 2010 [10], but

other forms of child maltreatment have been omitted.

Exposure to non-sexual child maltreatment, namely, physical

abuse, emotional abuse, and neglect, is associated with increased

risk of a wide range of psychological and behavioural problems,

including depression, alcohol abuse, anxiety, and suicidal behav-

iour, and with increased risk of HIV and herpes simplex virus type

2 (HSV2) infection [11–14]. However, the long-term health

consequences of these other forms of child maltreatment have not

been systematically examined. To address these omissions, clarify

the present state of empirical research, and enable the quantifi-

cation of the health impacts of child neglect, physical abuse, and

emotional abuse at the population level using burden of disease

and comparative risk assessment methodology, we conducted a

systematic review of the scientific literature and quantitative meta-

analyses. To the best of our knowledge, this is the first meta-

analysis to summarise the evidence for associations between

individual types of non-sexual child maltreatment and outcomes

related to mental and physical health.

Methods

General recommendations from the PRISMA 2009 revision

[15], with regard to processing and reporting of results, were taken

Table 1. Definition of child maltreatment.

Type of Maltreatment Description

Physical abuse Physical abuse of a child is defined as the intentional use of physical force against a child that results in—or has a high likelihood of resulting in—harm for the child’s health, survival, development, or dignity. This includes hitting, beating, kicking, shaking, biting, strangling, scalding, burning, poisoning, and suffocating. Much physical violence against children in the home is inflicted with the object of punishing.

Sexual abuse Sexual abuse is defined as the involvement of a child in sexual activity that he or she does not fully comprehend, is unable to give informed consent to, or for which the child is not developmentally prepared, or else that violates the laws or social taboos of society. Children can be sexually abused by both adults and other children who are—by virtue of their age or stage of development—in a position of responsibility, trust, or power over the victim.

Emotional and psychological abuse Emotional and psychological abuse involves both isolated incidents, as well as a pattern of failure over time on the part of a parent or caregiver to provide a developmentally appropriate and supportive environment. Acts in this category may have a high probability of damaging the child’s physical or mental health, or his/her physical, mental, spiritual, moral, or social development. Abuse of this type includes the following: the restriction of movement; patterns of belittling, blaming, threatening, frightening, discriminating against, or ridiculing; and other non-physical forms of rejection or hostile treatment.

Neglect Neglect includes both isolated incidents, as well as a pattern of failure over time on the part of a parent or other family member to provide for the development and well-being of the child—where the parent is in a position to do so—in one or more of the following areas: health, education, emotional development, nutrition, shelter, and safe living conditions. The parents of neglected children are not necessarily poor.

Adapted from Butchart et al. [5]. doi:10.1371/journal.pmed.1001349.t001

Consequences of Child Nonsexual Maltreatment

PLOS Medicine | www.plosmedicine.org 2 November 2012 | Volume 9 | Issue 11 | e1001349

into account (Text S1). The meta-analysis conforms to the

guidelines outlined by the Meta-analysis of Observational Studies

in Epidemiology recommendations [16]. Methods and inclusion

criteria were specified in advance and documented in a review

protocol (Text S2).

Inclusion and Exclusion Criteria This systematic review and meta-analysis incorporated retro-

spective and prospective cohort, cross-sectional, and case-control

studies meeting the following inclusion criteria: (1) the study

reported original, empirical research published in a peer-reviewed

journal, (2) the study considered non-sexual child maltreatment as

a potential risk factor for loss of health, and (3) the related health

outcomes or behavioural risk factors were among those listed in

the Global Burden of Diseases, Injuries, and Risk Factors Study

[10]. Studies reporting exposure only to combined types of abuse

were excluded. Included studies reported odds ratios (ORs) and

confidence intervals (CIs) comparing those exposed and not

exposed by type of abuse or, alternatively, provided the

information from which effect sizes and confidence intervals could

be calculated (Text S2).

Search Strategy Three electronic databases (Medline, EMBASE, and PsycINFO

up to 26 June 2012) were searched using full text and Medical

Subject Headings (MeSH) terms to identify studies reporting an

association between non-sexual child maltreatment and health

outcomes (Text S2). Truncation of terms was used to capture

variation in terminology. The search was not restricted to the

English language, nor restricted by any other means. Searches

were conducted using synonyms and combinations of the following

search terms: ‘‘maltreatment’’, ‘‘physical abuse’’, ‘‘psychological

abuse’’, and ‘‘emotional abuse’’, and automatic explosion of the

terms ‘‘child abuse’’ and ‘‘child neglect’’. The search was also not

restricted to any particular health outcome. Instead, the broader

terms ‘‘risk’’, ‘‘adverse effect’’, ‘‘consequences’’, ‘‘harm’’, and ‘‘as-

sociation’’ were used to encompass all studies that investigated any

adverse outcome of non-sexual child maltreatment. In addition,

reference lists of selected studies were screened for any other

relevant study, and additional studies were also identified through

contact with study authors. Articles in languages other than

English were translated.

Data Collection and Quality Assessment The full-text article of any study that appeared to meet the

inclusion criteria was retrieved for closer examination. Two

reviewers (R. E. N. and M. B.) independently assessed articles for

eligibility. Disagreements were resolved by consensus. The coders

were not masked to the journals or authors of the studies reviewed. A

standardised data extraction sheet was developed, and data retrieved

included publication details, country where study was conducted,

methodological characteristics such as sample size and study design,

exposure and outcome measures, type of abuse, and health outcomes

(Text S2). The data extraction sheet included a quality assessment

tool (Table 2) to rate the methodological quality of each study based

on the Newcastle-Ottawa Scale for assessing the quality of

observational studies [17]. Quality assessment was completed

independently by two reviewers, and disagreements were resolved

by discussion. One author was contacted for further information.

Statistical Analyses Weighted summary measures were computed using MetaXL,

version 1.2 [18], a tool for meta-analysis in Microsoft Excel, with

ORs chosen as the principal summary measure. Heterogeneity

was quantitatively assessed using the Cochran’s Q and I2 statistics

to evaluate whether the pooled studies represent a homogeneous

distribution of effect sizes. Evidence of publication bias was

investigated by means of funnel plots using the standard error on

the y-axis [19].

Meta-analyses were complicated by the presence of significant

heterogeneity in the data, likely due to a combination of true

variance in these relationships and variability produced by

differences in the methodology used to measure exposure and

outcomes. We hypothesised that effect size may differ according to

the methodological quality of the studies. MetaXL implements a

process to explicitly address study heterogeneity caused by

differences in study quality. This so-called quality effects (Doi

and Thalib) model [20] is a modified version of the fixed-effects

inverse variance method that additionally allows giving greater

weight to studies of high quality versus studies of lesser quality by

using the quality scores assigned to each study to weigh studies not

only according to sample size but also by study quality [20,21].

Forest plots were made to visualise individual as well as pooled

effects.

To address the effects of important study characteristics and

explore heterogeneity, we additionally conducted several pre-

specified subgroup analyses (depending on data availability) by the

following: gender of participants in the sample, geographic

location (high income versus low-to-middle income), type of

sample (population-based versus non-representative samples),

measurement of abuse (self-reported versus official records),

assessment of health outcome (structured clinical interview versus

self-reported), prospective versus retrospective assessment of abuse

and neglect, and appropriate adjustment versus no or inadequate

adjustment for confounders.

Results

Out of 285 articles assessed for eligibility, 124 studies provided

evidence of a relationship between non-sexual child maltreatment

and various health outcomes for use in subsequent meta-analyses

(Figure 1). The majority (n = 112) were from Western Europe,

North America, Australia, and New Zealand. Data from low- and

middle-income countries were sparse. Only 16 studies used a

prospective cohort design that followed abused or neglected

children over time to identify later health outcomes (Table 3). The

remaining studies included cohort, cross-sectional, and case-

control studies that measured the maltreatment retrospectively,

usually by self-report in adolescence or adulthood. Most of the

studies included in our meta-analysis presented data from regional

or nationally representative samples (Table 3). The results of

primary meta-analyses are presented in Tables 4–6, with Figures

S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S13, S14, S15,

S16, S17, S18, S19, S20, S21, S22, S23, S24, S25, S26, S27, S28,

S29, S30, S31, S32, S33, S34, S35, S36, S37, S38, S39, S40, S41,

S42 showing the forest plots of these meta-analyses. Details of

subgroup analyses are presented in Tables S1, S2, S3, S4, S5, S6,

S7, S8, S9, S10, S11.

Mental Disorders Physically abused (OR = 1.54; 95% CI 1.16–2.04), emotionally

abused (OR = 3.06; 95% CI 2.43–3.85), and neglected (OR = 2.11;

95% CI 1.61–2.77) individuals were found to have a higher risk of

developing depressive disorders than non-abused individuals

(Table 4; Figures S1, S2, S3). The test for heterogeneity was highly

significant, with p,0.01 for both abuse types and neglect. Funnel plots indicate the possibility of publication bias for physical abuse, as

Consequences of Child Nonsexual Maltreatment

PLOS Medicine | www.plosmedicine.org 3 November 2012 | Volume 9 | Issue 11 | e1001349

it appears that some smaller, less precise studies have a greater effect

size than the larger studies, and there are no smaller studies to the

left (negative) side of the graph, suggesting that some negative

studies may never have been published (Figure S4).

For physical abuse, emotional abuse, and neglect, OR estimates

in males were higher than in females, but the difference was not

statistically significant (Table S1). The odds of developing

depressive disorders with exposure to physical abuse were greatest

in prospective studies. Although the OR point estimate was higher

in subgroup analyses of studies where exposure to physical abuse

was court-substantiated by official records—which would include

the more severe cases of abuse (OR = 2.41; 95% CI 1.32–4.41)—

compared with self-reported physical abuse (OR = 1.56; 95% CI

1.11–2.19) and physical punishment (OR = 1.20; 95% CI 0.88–

1.61), the 95% CIs were overlapping, and these differences were

not statistically significant. There was a stronger association

between physical abuse and a diagnosis of major depressive

disorder using structured interviews (OR = 1.82; 95% CI 1.44–

2.30) than when depressive disorders were diagnosed by symptom

scales (OR = 1.52; 95% CI 1.03–2.24), but again these differences

were not statistically significant (Table S1). Restricting the physical

abuse analysis to studies from high-income countries increased the

odds of developing depressive disorders to 1.58 (95% CI 1.18–

2.12), but the association was not significant in low-to-middle-

income countries (Table S1).

However, for neglect in childhood, similar odds of developing

depressive disorders were observed in high- and low-to-middle-

income countries. Data from two studies suggest a dose–response

relationship, with depression more likely with frequent neglect

compared with neglect that occurred only sometimes in childhood

[13,22]. A dose–response relationship was also reported for

emotional abuse and depressive disorders, but not for physical

abuse and depressive disorders (Table S1).

Physical abuse (OR = 1.51; 95% CI 1.27–1.79), emotional

abuse (OR = 3.21; 95% CI 2.05–5.03), and neglect (OR = 1.82;

95% CI 1.51–2.20) were associated with a significantly increased

risk of anxiety disorders (Figures S5, S6, S7, S8). For physical

abuse, significant associations were also observed with post-

traumatic stress disorder (PTSD) and panic disorder diagnoses

(Table S2). A dose–response relationship was observed with

physical abuse but not with emotional abuse and neglect [22],

with anxiety disorders more likely with frequent physical abuse

than with abuse that occurred only sometimes in childhood

(Table S2). Physical abuse, emotional abuse, and neglect were

also associated with an almost 3-fold increased risk of developing

eating disorders (Figures S9, S10, S11, S12), and physical abuse

was associated with a 5-fold increased risk of developing bulimia

nervosa meeting Diagnostic and Statistical Manual of Mental

Disorders (DSM) diagnostic criteria. Most of the evidence came

from retrospective studies, and only one prospective study [23]

reported a strong association with neglect in childhood (Table

S3). A dose–response relationship was also observed, with bulimia

nervosa more likely with more severe and repeated physical abuse