Chronic abdominal pain (CAP) is one of the most common pediatric complaints, with a reported prevalence in Western countries of 0.3% to 19% (1). Complaints of abdominal pain are often long-lasting, with many children experiencing a reduced quality of life and anxiety (2,3). The average cost of diagnostic evaluation of CAP in children is high, being estimated at $6104.30 per patient in the United States (4).
In the late 1950s, CAP was defined by Apley and Naish (5) as recurrent abdominal pain (RAP) with at least 3 episodes in 3 months or more. A decade ago, this definition was revised by a panel of pediatric gastroenterologists, who established the Rome III criteria for abdominal pain–related functional gastrointestinal disorders (FGIDs). Since then, CAP has been subdivided into 5 categories based on symptomatology and lack of evidence of organic causes (6,7). These categories differ in the location of pain, the existence of a relation with defecation, and the extent of loss of daily functioning.
Multiple factors play a role in the pathophysiology of CAP, but the precise etiology is not yet well understood (8). The brain–gut axis is considered to play an important role in causing CAP, as well as bowel motility, psychological factors, and stressful life events such as the disruption of personal relationships and childhood sexual abuse (CSA) (9–12).
The definition of CSA differs among countries, but is more or less based on the definition as proposed by Kempe in 1977 (13): “Sexual abuse occurs when a child is engaged in sexual activities that he or she cannot comprehend, for which he or she is developmentally unprepared and cannot give consent, and/or that violate the law or social taboos of society.” Sexual activities may include sexual contact with the child (which can be oral-genital, genital, or anal), as well as sexual activities that do not involve contact (eg, exhibitionism, voyeurism, using the child in the production of pornography) (13). In the Adverse Childhood Experiences study (14), 25% of women and 16% of men reported having experienced a form of CSA. Reported prevalence rates of CSA differ among studies because of variations in CSA definition, incidence, cumulative prevalence outcomes, self-report, or reports by caregivers or professionals. The Fourth National Incidence Study of Child Abuse and Neglect (NIS-4) found an incidence of CSA known to professionals of 2.4/1000/year (15). In the Netherlands, the incidence of CSA known to professionals is 0.8/1000 children each year, with a prevalence of 4% (16).
In developed countries (United Kingdom, United States, Canada, Australia), the retrospective self-reported cumulative prevalence of any form of CSA (noncontact, contact or penetrative) is 15% to 30% for girls and 5% to 15% for boys, whereas penetrative CSA is reported in 5% to 10% of girls and 1% to 5% of boys (17). In Swedish adolescents (mean age 18.15 years), self-reported cumulative prevalence of any form of CSA is 64.8% in girls, 22.7% in boys, and penetrative CSA is reported in 13.5% of girls and 5.5% of boys (18). The worldwide prevalence of any form of CSA is estimated on 8% to 31% for girls and 3% to 17% for boys (19). Victims of CSA experience a wide range of acute and chronic effects, which are physical and/or psychological in nature. These include age-inappropriate sexual behavior or knowledge, school problems, anxiety, depression, posttraumatic stress disorder, alcohol or drug abuse, suicide, and pain symptoms (20–22). Several pain syndromes, including CAP, are reported as long-term somatic complaints (23–26).
In adults, a history of sexual abuse is found in 31.6% to 44% of all patients with gastrointestinal (GI) complaints, especially in those with functional disorders (26–29). Although data show that CAP is frequently present in sexually abused children (25), no reliable data exist on the prevalence of CSA among pediatric patients with CAP. We therefore conducted a systematic review to determine the prevalence of CSA in children with CAP.
We searched the electronic database MEDLINE by PubMed (1953–July 27, 2012), and the databases EMBASE (1980 to July 27, 2012), PsychInfo (1806–July 27, 2012), and ERIC (1965–July 27, 2012) by Ovid. The main search design consisted of 3 components combined by “AND”: “Child sexual abuse AND Child/Adolescent AND Gastrointestinal disease/symptom.” Synonyms for these terms were combined with the corresponding component with “OR,” including database-specific MeSH and thesaurus terms and text words.
The MEDLINE search was ((“Child Abuse, Sexual”[Mesh] AND (“Child”[Mesh] OR “Adolescent”[Mesh] OR “Child, Preschool”[Mesh]))) AND (gastrointestinal diseases [Mesh] OR Abdominal pain[Mesh] OR abdominal migraine[tiab] OR dyspepsia[tiab] OR irritable bowel syndrome[tiab] OR functional abdominal pain[tiab] OR chronic abdominal pain[tiab] OR recurrent abdominal pain[tiab]). The other databases were searched using the MEDLINE search method converted into a database-specific search. Additionally, we scanned reference lists of relevant articles and conducted a cited reference search of these articles in the Web of Science databases.
Study selection was independently performed by 2 authors (L.P.S., E.M.M.H.K.) and disagreement was resolved through discussion. First, all references were screened by title. Next, possible relevant references were examined on the basis of abstracts and, if abstracts were not available, on the basis of the full text. Finally, the full text of all remaining articles was read to determine their eligibility for inclusion. Inclusion criteria were children ages 0 to 18 with CAP or any specific abdominal pain–related FGID; the prevalence or incidence of CSA as an outcome of the study; where a control group was investigated FGID or GI somatic complaints were required to be absent. Studies involving constipation, incontinence (nonretentive fecal incontinence), vomiting, aerophagia, or abdominal pain resulting from organic causes or medication were excluded.
There was no restriction in respect of publication year, publication status, or language. Authors were contacted for additional data if necessary.
The methodological quality of the studies included was systematically assessed by 2 authors (L.P.S., E.M.M.H.K.), using a standardized checklist (http://links.lww.com/MPG/A200) drawn from the QUADAS instrument (30) for assessment of the methodological quality of diagnostic accuracy studies. Lack of agreement was resolved by consensus (L.P.S., E.M.M.H.K.). The principal summary measure extracted was the prevalence of CSA in the selected population.
The literature search identified 269 articles. We selected 76 articles by title for abstract and/or full-text reading. Nine studies were identified as potentially relevant, 7 of which (12,31–36) were excluded on the basis of supplementary data provided by the authors. A figure, viewable online only (http://links.lww.com/MPG/A201), depicts the study selection process, with the reasons for exclusion. Finally, 2 studies, Woodbury's (37) and Alfvén's (38) met eligibility criteria and were included. The characteristics of the studies included are listed in Table 1.
Woodbury (37) investigated stressful life events as stressors for the onset of CAP (defined as RAP consistent with the Apley and Naish criteria (5)) in children ages 4 to 21 years (mean age 8) (Table 1). Only children with persistent CAP and loss of daily functioning were included and referred by the hospital's GI medical clinic to a psychiatric consultant. Fifty children (21 girls, 29 boys) and their parents were interviewed based on DSM-III-R criteria in 1 to 6 meetings, depending on their willingness to cooperate. Children's schoolteachers provided additional information. In 4 children (8%) with CAP, sexual abuse in the preceding 2 years by nonfamily members was reported as the cause of their complaints. No standardized interview method was used.
In the second study included (Alfvén (38)), 100 children ages 6 to 15 years with RAP and their parents were interviewed by a pediatrician at a stomach pain clinic. Interview questions included pain history, stressors for the complaints, and psychosocial circumstances. The first interview session took 90 minutes and in the case of diagnostic uncertainty, additional interviews were held. In unclear cases, teenagers were also interviewed without the parents’ presence and were specifically asked for experiences of CSA (G. Alfvén, personal communication, 2011). The pain was diagnosed as psychosomatic (CAP) if meeting Apley and Naish's criteria plus at least 6 of 7 supplementary criteria (Table 1). A psychosomatic diagnosis was made in 48 cases, of which 1 child (2%) reported sexual abuse as a life event occurring at the time of onset of CAP. Reports of life events were limited to the period of onset of CAP. Apart from a standardized pain questionnaire, no standardized interview method was used.
Risk of Bias
The methodological quality of the studies included is summarized in Table 2. Alfvén (38) scored as adequate 6 of 15 items addressing the risk of bias and Woodbury (37) scored 7. Both studies used a nonreplicable instrument to diagnose the target condition, and CSA was not investigated in all subjects.
This systematic review identified only 2 small studies including 98 children (37,38), which describe the prevalence of CSA in children with CAP. The prevalence of CSA as found in these studies varies from 2% to 8%.
Comparability With Other Research Results
Several studies of adults report a high prevalence (range 31.6%–44%) of sexual abuse among patients with CAP symptoms (26,31,39). The prevalence of CSA in children with CAP as found in this review (2%–8%) is lower than that in adult patients with CAP, and is comparable with the 4% prevalence rate of CSA known to professionals in the general population (16); however, the self-reported cumulative prevalence rates of any form of CSA in the general population (8%–64.8% for girls, 3%–22.7% for boys (17–19)) are much higher than the prevalence of CSA in children with CAP found in this review.
Only 2 studies with low methodological quality were identified in this systematic review, which undermines the reliability of the 2% to 8% prevalence. In general, because no criterion standard exists to determine whether a child has been sexually abused, it is unknown whether a reported prevalence of CSA is a reflection of the true prevalence.
Number of Studies
The lack of studies in this field may be explained by the rise of ethical considerations when investigating experience(s) of sexual abuse in children who “simply” complain of abdominal pain. Doctors may be afraid of unnecessarily worrying parents or of falsely accusing them because this could cause a negative atmosphere in a diagnostic interview. Moreover, CSA is difficult to detect because of several factors such as a low specificity of symptoms (40) and feelings of guilt, nonunderstanding, and distrust in abused children resulting in unwillingness to talk about their experiences (41). Factors influencing the willingness of children to tell others about CSA could be whether the perpetrator is someone close to them (eg, a parent vs a vague friend of the family), whether the abuse has stopped, the age of the child, whether violence or threat are used, and how well they know and trust the interviewer (41,42). Studies investigating the prevalence of CSA are thus difficult to conduct. Little or no information on these aspects was available in the studies included in this review.
Other Studies Investigating the Relation Between CSA and CAP
Van Tilburg et al (25) investigated the association between abdominal pain and sexual abuse in reverse. In this prospective study, 845 children (ages 4–12 years) at risk for abuse and neglect and their parents listed unexplained GI symptoms during the previous 6 months in self-report questionnaires (Child Behavior Check List and Youth Self Report (43)). In 91% of children who experienced CSA, that experience preceded or coincided with unexplained abdominal pain. However, organic causes were not investigated and symptoms were rated positive if either the child or a parent reported the symptom, with children reporting 2 to 3 times more often than parents.
Hyman (32) investigated visceral pain-associated disability syndrome, defined as at least 2 months of abdominal or chest pain with severe loss of daily functioning, a lack of organic substrate, and failure of several earlier therapies, in 40 children. Precursors of the syndrome were identified by chart reviews and interviews covering inter alia life-changing events and family problems. None of the subjects was asked about or investigated on a history of CSA, but CSA was in fact spontaneously reported in some cases during interviews or previously recorded in the medical chart (P. Hyman, personal communication, 2011). Three parents (7.5%) reported sexual abuse as an unresolved family problem, but it is not clear whether the child in question was abused. In 2 children (5%), a CSA experience was reported as the event triggering the symptoms.
Van Oudenhove et al (44) recently completed a study on the association of a history of abuse with gastric sensitivity and gastric emptying in functional dyspepsia. Sexual abuse history was assessed in 201 subjects (age 15.5–71 years) by means of self-report dichotomous questionnaires, and 21.4% reported a history of sexual abuse; however, the subjects of the present study were mainly adults seen in tertiary care centers. No information is provided about the onset of functional dyspepsia and the period of sexual abuse.
Quality of Included Studies
The report bias in Alfvén's study and possibly Woodbury's study could underestimate the prevalence of CSA. If authors did not explicitly mention CSA to all patients, then it was reported on a voluntary basis, possibly resulting in an underestimation of the prevalence found. Moreover, in an interview setting, only known CSA can be reported by parents. Even if a CSA experience is known, a report bias by parents is still likely because in most cases, it occurs in family settings (15) and the parent(s) could therefore be the perpetrator(s). The fact that no records of Child Protective Services were checked for CSA experiences and the subject of CSA was not explicitly mentioned in the interviews suggest that the rates of 2% and 8% are probably an underestimation. The lack of a criterion standard for determining CSA makes the interpretation of these data even more difficult. It is not possible to say to what extent the prevalence would increase if the possibilities for parents and children to report CSA were enhanced and the risk of bias could be diminished.
In adults, the prevalence of CSA is positively related to the severity of CAP symptoms (28). The selection bias in Woodbury's study could therefore result in a higher prevalence of CSA.
Because no control groups were involved, prevalence rates cannot be compared with the prevalence of CSA in healthy subjects. These limitations of the studies included being the case results should be interpreted with caution in expectation of future studies.
The main strength of the present study is its systematic review of all available literature on CSA in children with CAP. This systematic review reveals a lack of knowledge on the prevalence of CSA in children diagnosed as having CAP. A limitation of this review is that no methodologically well-designed studies were identified so as to estimate a reliable prevalence.
This review shows that reliable data on the prevalence of CSA in children with CAP are lacking and prospective well-designed studies are important. On the contrary, diagnosing CSA is difficult and can best be achieved by combining the results of a complete (medical) history obtained from the parents, a complete physical examination (head to toe), including detailed genital examination, and a standardized and validated child interview integrating a measurement to test the child's sexual knowledge, one of the most specific indicators of CSA (45,46). To our knowledge, the Sexual Knowledge Picture Instrument (45) is the only instrument available for the reliable measurement of children's sexual knowledge, but further research on the validation of this instrument is required for its use by international professionals in identifying signs of CSA. For a reliable indication of the prevalence of CSA in children with CAP, this combined and systematic approach should be used for a study including an adequate sample of children with CAP and a control group without CAP.
Detection of CSA is important because only in this way can future CSA experiences be prevented. Early detection and somatic and psychological treatment can prevent later somatic and psychological consequences of CSA (20–22,25,28). It is most likely that CAP is partially mediated by the psychological distress caused by CSA (47–49). Evidence-based therapies for the trauma caused by CSA may fundamentally improve the outcome of CAP.
This systematic review describes the existing gap in the literature concerning the prevalence of CSA in children with CAP. A better understanding of the contribution of CSA to the etiology of CAP could improve the prognosis of CAP and save children from further CSA victimization. Future research using standardized and validated instruments in large samples including control groups is needed to determine the prevalence of CSA in children with CAP.
The authors thank Arnold G.E. Leenders, clinical librarian of the medical library at the Academic Medical Center, for contributing to the development of a well-designed literature search.
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