Breaking the vicious circle of fear and avoidance in children with abdominal pain: A mediation analysis

Brief cognitive-behavioral treatment for avoidant/restrictive food intake disorder in the context of functional dyspepsia: Study protocol for a feasibility randomized controlled trial

BACKGROUND

Avoidant/restrictive food intake disorder (ARFID) symptoms are common (up to 40%) among adults with functional dyspepsia (FD), a disorder of gut-brain interaction characterized by early satiation, post-prandial fullness, epigastric pain, and/or epigastric burning. Using an 8-session exposure-based cognitive-behavioral treatment (CBT) for adults with FD + ARFID compared to usual care (UC) alone, we aim to: (1) determine feasibility, (2) evaluate change in clinical outcomes in, and (3) explore possible mechanisms of action.

METHODS

We will randomize adults with FD who meet criteria for ARFID with ≥5% weight loss (N = 50) in a 1:1 ratio to CBT (with continued UC) or to UC alone. A priori primary benchmarks will be: ≥75% eligible participants enroll; ≥75% participants complete assessments; ≥70% participants attend 6/8 sessions; ≥70% of sessions have all content delivered; ≥70% participants rate Client Satisfaction Questionnaire scores above scale midpoint. We will also examine the size of changes in FD symptom severity and related quality of life within and between groups, and explore possible mechanisms of action.

CONCLUSIONS

Findings from this trial will inform next steps with treatment development or evaluation-either for further refinement or for next-step efficacy testing with a fully-powered clinical trial.

Advancing the Assessment and Treatment of Comorbid Pediatric Chronic Functional Abdominal Pain (CFAP) and Restrictive Eating Disorders

The aim of this review is to heighten awareness of the association between chronic functional abdominal pain (CFAP) and restrictive eating disorders (ED) in adolescents. We describe current diagnostic practices and propose future research efforts to improve the assessment and treatment of comorbid CFAP and restrictive EDs. A narrative review of the literature on CFAP and EDs was performed using PubMed, JSTOR, ScienceDirect, and PsycINFO and the following search terms: 'restrictive eating disorders', 'chronic functional abdominal pain', 'chronic pain' 'treatment' 'diagnosis' and 'adolescents'. Published studies on restrictive EDs and CFAP from May 2008 to March 2023 were included. Ascribable to the overlap in etiology and symptom presentation, adolescents with chronic pain are significantly less likely to have their ED pathology promptly identified by providers compared to adolescents without comorbid chronic pain. This highlights the importance of the time sensitive and accurate identification of EDs in adolescents with CFAP. Overall, assessment methods are limited and EDs take longer to be identified in adolescents with comorbid CFAP. Future efforts should address diagnostic practices in pediatric settings and improve the communication among medical and mental health providers in order to promote the rapid and effective diagnosis and treatment of comorbid CFAP and EDs.

Clinical Impact of Systematic Assessment and Psychoeducation in Specialized Treatment of Adolescents with Severe Functional Somatic Disorders: Results from the AHEAD Study

Functional somatic disorders (FSD), characterized by persistent and disabling physical symptoms, are common in adolescents. Diagnostic uncertainty and insufficient illness explanations are proposed perpetuating factors that may constitute barriers for treatment engagement. This study describes the impact of manualized assessment and psychoeducation on diagnostic certainty and various clinical outcomes in adolescents with multi-system FSD. Ninety-one adolescents (15-19 years) received systematic assessment (4 h) and a subsequent psychiatric consultation (1.5 h). Clinical characteristics included self-reported physical health, symptom severity, illness perception, illness-related behavior, and psychological flexibility assessed before and approximately two months after assessment, prior to specialized treatment. Data were analyzed using t-tests. Immediately following assessment, 71 (80.7%) adolescents out of 88 reported a higher diagnostic certainty and 74 (84.1%) reported that attending assessment gave them positive expectations for future treatment. A clinically relevant improvement of physical health was not observed at two months but considerable reductions were seen in symptom severity, illness worry, negative illness perceptions, illness-related limiting behavior, and psychological inflexibility. The results emphasize that systematic assessment and psychoeducation are important in their own right in the specialized treatment of adolescents with severe FSD.

Gastrointestinal-Specific symptom anxiety in patients with gastroparesis: Relationships to symptom severity and quality of life

BACKGROUND

Gastrointestinal (GI)-specific anxiety has been identified as a treatment target in irritable bowel syndrome. However, GI-specific anxiety has been understudied in other GI functional/motility disorders. Among adults with gastroparesis, we aimed to: (1) initially validate a measure of GI-specific anxiety, the Visceral Sensitivity Index (VSI); and (2) evaluate the relationship between GI-specific anxiety and gastroparesis symptom severity and quality of life, compared to measures of anxiety, depression, and somatization.

METHODS

Consecutive adult patients (N = 100) with gastroparesis presenting for initial consultation completed a series of self-report measures including the VSI. We conducted a confirmatory factor analysis of the VSI one-factor structure and tested internal consistency and convergent validity. We then performed hierarchical linear regression analyses to explore associations between VSI and gastroparesis symptom severity and overall quality of life.

KEY RESULTS

Confirmatory factor analysis revealed that the original VSI one-factor structure overall fit well [χ2 (90) = 220.1, p < 0.0001; SRMR = 0.08; RMSEA = 0.12; CFI = 0.96]. The VSI also had excellent internal consistency (α = 0.99) and convergent validity (r = 0.29-0.56; all p < 0.01). Higher GI-specific anxiety was significantly associated with greater gastroparesis symptom severity, including nausea/vomiting, fullness/satiety, and upper abdominal pain scores beyond depression, anxiety, or somatization (all p = <0.01-0.01). Additionally, higher GI-specific anxiety was significantly associated with lower mental health-related quality of life, beyond gastroparesis symptom severity, depression, anxiety, or somatization (p = 0.01).

CONCLUSIONS & INFERENCES

The VSI is an adequate measure of GI-specific anxiety in patients with gastroparesis. Higher GI-specific anxiety was associated with increased patient-reported gastroparesis symptom severity and decreased quality of life, beyond depression/anxiety.

Nurse practitioner-delivered cognitive-behavioral treatment as a novel implementation route for irritable bowel syndrome: A proof of concept

BACKGROUND

Exposure-based cognitive-behavioral therapy (exposure-CBT) is efficacious for irritable bowel syndrome (IBS). However, few patients receive exposure-CBT due to a lack of behavioral health providers trained in brain-gut behavior therapies. Nurse practitioners (NPs) could fill a critical need for scalable delivery methods. In a pragmatic investigation of a 5-session NP-delivered exposure-CBT for adults with Rome IV-defined IBS, we evaluated treatment feasibility and acceptability and explored changes clinical outcomes.

METHODS

Exposure-CBT was delivered as part of routine care involving four sessions every other week and a 2-month booster session. Patients could electively participate in an observational study including pre-, mid-, and post-treatment surveys and a post-treatment qualitative interview. Independently coded ratings of NP treatment protocol adherence and competence ratings were completed from audio recordings, rated on a 1 (not at all) to 5 (completely) scale.

RESULTS

Twenty-five patients consented (ages 22-67 years; 76% female; 48% IBS-diarrhea predominant). There was high feasibility-adherence average = 4.1, NP competence average = 4.8, 72% treatment completion, 93% satisfaction scores ≥3. Treatment satisfaction was high (rated as 4/4 "very satisfied" by n = 9 and as 3/4 "mostly satisfied" by n = 5). There were improvements in clinical outcomes across treatment with large effects for IBS-symptom severity (-53%; Hedge's g = 1.0; 95% confidence interval [CI] = 0.5, 1.5) and IBS quality of life (+31%; Hedge's g = 0.8; 95% CI = 0.4, 1.2).

CONCLUSIONS

NP-delivered exposure-CBT for IBS was initially feasible and acceptable with promising clinical improvements. Findings will inform a future NIH Stage 1B/ORBIT Phase IIB pilot randomized control trial.

Development of a brief cognitive-behavioral treatment for avoidant/restrictive food intake disorder in the context of disorders of gut-brain interaction: Initial feasibility, acceptability, and clinical outcomes

BACKGROUND

Avoidant/restrictive food intake disorder (ARFID) symptoms are common (up to 40%) among adults with disorders of gut-brain interaction (DGBI), but treatments for this population (DGBI + ARFID) have yet to be evaluated. We aimed to identify initial feasibility, acceptability, and clinical effects of an exposure-based cognitive-behavioral treatment (CBT) for adults with DGBI + ARFID.

METHODS

Patients (N = 14) received CBT as part of routine care in an outpatient gastroenterology clinic. A two-part investigation of the CBT included a retrospective evaluation of patients who were offered a flexible (8-10) session length and an observational prospective study of patients who were offered eight sessions. Feasibility benchmarks were ≥75% completion of sessions, quantitative measures (for treatment completers), and qualitative interviews. Acceptability was assessed with a benchmark of ≥70% patients reporting a posttreatment satisfaction scores ≥3 on 1-4 scale and with posttreatment qualitative interviews. Mixed model analysis explored signals of improvement in clinical outcomes.

RESULTS

All feasibility and acceptability benchmarks were achieved (and qualitative feedback revealed high satisfaction with the treatment and outcomes). There were improvements in clinical outcomes across treatment (all p's < .0001) with large effects for ARFID fear (-52%; Hedge's g = 1.5; 95% CI = 0.6, 2.5) and gastrointestinal-specific anxiety (-42%; Hedge's g = 1.0; 95% CI = 0.5, 16). Among those who needed to gain weight (n = 10), 94%-103% of expected weight gain goals were achieved.

DISCUSSION

Initial development and testing of a brief 8-session CBT protocol for DGBI + ARFID showed high feasibility, acceptability, and promising clinical improvements. Findings will inform an NIH Stage 1B randomized control trial.

PUBLIC SIGNIFICANCE

While cognitive-behavioral treatments (CBTs) for ARFID have been created in outpatient feeding and eating disorder clinics, they have yet to be developed and refined for other clinic settings or populations. In line with the recommendations for behavioral treatment development, we conducted a two-part investigation of an exposure-based CBT for a patient population with high rates of ARFID-adults with disorders of gut-brain interaction (also known as functional gastrointestinal disorders). We found patients had high satisfaction with treatment and there were promising improvements for both gastrointestinal and ARFID outcomes. The refined treatment includes eight sessions delivered by a behavioral health care provider and the findings reported in this article will be studied next in an NIH Stage 1B randomized controlled trial.

Future of Brain-Gut Behavior Therapies: Mediators and Moderators

With growing evidence to support their efficacy, brain-gut behavior therapies are increasingly viewed as a key component to integrated care management of disorders of gut-brain interaction. However, the types of brain-gut behavior therapies differ in how and for whom they purportedly work. We provide a conceptual review of these brain-gut behavior therapies, with an emphasis on describing how (ie, mechanisms) and for whom (ie, moderators) they work as hypothesized and/or supported by evidence. Based on evidence to date, we recommend that brain-gut behavior therapies prioritize gastrointestinal-specific targets, such as gastrointestinal-specific anxiety.

Parental responses and catastrophizing in online cognitive behavioral therapy for pediatric functional abdominal pain: A mediation analysis of a randomized controlled trial

Objective

To test if decreased parental protective behaviors, monitoring behaviors, and parental catastrophizing mediate relief of gastrointestinal symptoms in children 8-12 years with functional abdominal pain disorders (FAPDs). The study uses secondary data analyses of a randomized controlled trial in which exposure-based online cognitive behavioral therapy (ICBT) was found superior to treatment as usual in decreasing gastrointestinal symptoms.

Methods

The ICBT included 10 weekly modules for children and 10 weekly modules for parents. Treatment as usual consisted of any medication, dietary adjustments, and healthcare visits that the participants engaged in during 10 weeks. All measures were self-assessed online by parents. Biweekly assessments of the Adult Responses to Children's Symptoms (ARCS), Protect and Monitor subscales, and the Pain Catastrophizing Scale, parental version (PCS-P) were included in univariate and multivariate growth models to test their mediating effect on the child's gastrointestinal symptoms assessed with the Pediatric Quality of Life Gastrointestinal Symptoms Scale (PedsQL).

Results

A total of 90 dyads of children with FAPDs and their parents were included in the study, of which 46 were randomized to ICBT and 44 to treatment as usual. The PCS-P was found to mediate change in the PedsQL ab = 0.639 (95% CI 0.020-2.331), while the ARCS Monitor ab = 0.472 (95% CI -1.002 to 2.547), and Protect ab = -0.151 (95% CI -1.455 to 0.674) were not mediators of change.

Conclusions

To target parental catastrophizing in ICBT for pediatric FAPDs is potentially important to reduce abdominal symptoms in children.

Psychological treatment for pediatric functional abdominal pain disorders

PURPOSE OF REVIEW

The purpose of this review is to discuss up-to-date psychological treatment strategies for functional abdominal pain disorders (FAPDs) with practical implications for primary care providers who are the "front line" of treatment for pediatric FAPD.

RECENT FINDINGS

Positive diagnosis, pain education, and access to multidisciplinary care improve outcomes for FAPD patients. Cognitive behavioral therapy (CBT) and hypnosis continue to have the strongest evidence in psychological treatments, but educational interventions and other nonpharmacological approaches show promise as well. There are innovative programs that combine these tools into group or internet-based treatments to expand access to care. Additionally, nonpharmacological tools, including neurostimulation and virtual reality programs, are increasing in popularity.

SUMMARY

FAPD is prevalent across pediatric practices, yet there is no standard medical or dietary approach, and there are many barriers to diagnosis and treatment. It is important for patients to have positive encounters around diagnosis and education, access to multidisciplinary care, and integrated psychological support. Consistently, studies show that psychology continues to be a vital component of care. This review discusses supported uses of psychology, innovative programming for increasing access to care, and how primary care providers can incorporate lessons learned from psychology in FAPD care.

VIDEO ABSTRACT

http://links.lww.com/MOP/A67 .

A unified Internet-delivered exposure treatment for undifferentiated somatic symptom disorder: single-group prospective feasibility trial

BACKGROUND

Exposure-based psychological treatment appears to have beneficial effects for several patient groups that commonly report distress related to persistent somatic symptoms. Yet exposure-based treatment is rarely offered in routine care. This may be because existing treatment protocols have been developed for specific symptom clusters or specific unwanted responses to somatic symptoms, and many clinics do not have the resources to offer all these specialised treatments in parallel. In preparation for a randomised controlled trial, we investigated the feasibility of a new and unified Internet-delivered exposure treatment (OSF.io: cnbwj) for somatic symptom disorder regardless of somatic symptom domain (e.g. cardiopulmonary, fatigue, gastrointestinal, pain), combination of unwanted emotions (e.g. anger, anxiety, fear, shame) and whether somatic symptoms are medically explained or not. We hypothesised that a wide spectrum of subgroups would show interest, that the treatment would be rated as credible, that adherence would be adequate, that the measurement strategy would be acceptable and that there would be no serious adverse events.

METHODS

Single-group prospective cohort study where 33 self-referred adults with undifferentiated DSM-5 somatic symptom disorder took part in 8 weeks of unified Internet-delivered exposure treatment delivered via a web platform hosted by a medical university. Self-report questionnaires were administered online before treatment, each week during treatment, post treatment and 3 months after treatment.

RESULTS

Participants reported a broad spectrum of symptoms. The Credibility/Expectancy mean score was 34.5 (SD = 7.0, range: 18-47). Participants completed 91% (150/165) of all modules and 97% of the participants (32/33) completed at least two exposure exercises. The average participant rated the adequacy of the rationale as 8.4 (SD = 1.5) on a scale from 0 to 10. The post-treatment assessment was completed by 97% (32/33), and 84% (27/32) rated the measurement strategy as acceptable. The Client Satisfaction Questionnaire mean score was 25.3 (SD = 4.7, range: 17-32) and no serious adverse events were reported. Reductions in subjective somatic symptom burden (the Patient Health Questionnaire 15; d = 0.90) and symptom preoccupation (the somatic symptom disorder 12; d = 1.17) were large and sustained.

CONCLUSIONS

Delivering a unified Internet-delivered exposure-based treatment protocol for individuals with undifferentiated somatic symptom disorder appears to be feasible.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT04511286 . Registered on August 13, 2020.

Validation of child-adapted short scales for measuring gastrointestinal-specific avoidance and anxiety

Aim

To validate child‐adapted shortened versions of the Irritable Bowel Syndrome‐Behavioural Responses Questionnaire (IBS‐BRQ; short scale denoted BRQ‐C) and the Visceral Sensitivity Index (VSI; short scale denoted VSI‐C) for children with functional abdominal pain disorders (FAPDs).

Methods

A child psychologist supervised by a child gastroenterologist was responsible for shortening the scales (BRQ‐C, 11 items; and VSI‐C, 7 items). Then, a sample of 89 children aged 8–12 years with FAPDs was used in the validation. Construct validity was assessed with correlations. Measures included gastrointestinal symptoms, quality of life, pain intensity and anxiety. Also, internal consistency, test–retest reliability, administration time and factor structure were assessed.

Results

Internal consistency for the BRQ‐C and the VSI‐C was α = 0.84 and α = 0.80, respectively. Correlations with related scales were similar between child‐adapted scales and original scales, indicating construct validity equivalence. Correlations between short scales and original scales were high. Mean administration time was reduced by 47% (BRQ‐C) and 42% (VSI‐C), compared with original scales. Test–retest reliability was r = 0.72 for BRQ‐C and r = 0.83 for VSI‐C. BRQ‐C had two factors (Avoidance and Bowel control). VSI‐C had a unifactorial structure.

Conclusion

The BRQ‐C and the VSI‐C were found to be time‐saving, reliable and valid for children with FAPDs.

Non-pharmacological management of pediatric functional abdominal pain disorders: Current evidence and future perspectives

Functional abdominal pain disorders (FAPDs) are an important and prevalent cause of functional gastrointestinal disorders among children, encompassing the diagnoses of functional dyspepsia, irritable bowel syndrome, abdominal migraine, and the one not previously present in Rome III, functional abdominal pain not otherwise specified. In the absence of sufficiently effective and safe pharmacological treatments for this public problem, non-pharmacological therapies emerge as a viable means of treating these patients, avoiding not only possible side effects, but also unnecessary prescription, since many of the pharmacological treatments prescribed do not have good efficacy when compared to placebo. Thus, the present study provides a review of current and relevant evidence on non-pharmacological management of FAPDs, covering the most commonly indicated treatments, from cognitive behavioral therapy to meditation, acupuncture, yoga, massage, spinal manipulation, moxibustion, and physical activities. In addition, this article also analyzes the quality of publications in the area, assessing whether it is possible to state if non-pharmacological therapies are viable, safe, and sufficiently well-based for an appropriate and effective prescription of these treatments. Finally, it is possible to observe an increase not only in the number of publications on the non-pharmacological treatments for FAPDs in recent years, but also an increase in the quality of these publications. Finally, the sample selection of satisfactory age groups in these studies enables the formulation of specific guidelines for this age group, thus avoiding the need for adaptation of prescriptions initially made for adults, but for children use.

Mediation of outcomes for cognitive behavioral therapy targeted to parents of children with Functional Abdominal Pain Disorders

OBJECTIVE

There is a large body of evidence for the efficacy of Cognitive Behavioral Therapy (CBT) in treating Functional Abdominal Pain Disorders (FAPD) in children. In most CBT interventions for FAPD, parents participate together with their children. However, only one study to date has examined targeting parents alone for treatment. The aim of the current study was to examine mediators of a parent-only CBT treatment incorporating social learning (SLCBT) for FAPD in children.

METHODS

We examined mediators of child outcomes in an existing randomized controlled trial (n = 316) of parent-only social learning CBT compared to an education condition. Hypothesized mediators (parental protectiveness, perceived threat of pain, catastrophizing) were assessed at 3 months post-treatment, and outcomes (parent ratings of disability, quality of life, school absences, and health care visits) were assessed at 6 months post-treatment. Mediation analyses were performed using Hayes' PROCESS macro.

RESULTS

Pain catastrophizing significantly mediated treatment effects for all outcomes (B ranged from -1.65 to 2.22). Reduction in pain threat was a significant mediator for all outcomes (B ranged from -1.84 to 3.13) except school absences and health care visits. Decrease in parental protectiveness mediated effects on disability and missed school (B ranged from -1.47 to 1.34). Mediation effects did not differ by in-person or remote delivery of SLCBT.

CONCLUSION

Changes in maladaptive parental thoughts and behaviors following parent-only SLCBT intervention appeared to mediate the effects of the intervention. Parental catastrophizing appears to be a particularly important target given that decreases in that variable mediated all outcomes.

Allergy-related diseases in childhood and risk for abdominal pain-related functional gastrointestinal disorders at 16 years-a birth cohort study

BACKGROUND

Studies on allergy-related diseases in relation to abdominal pain-related functional gastrointestinal disorders (AP-FGIDs) in children are few and results are contradictory. We examined the associations between childhood allergy-related diseases and adolescent AP-FGIDs in general and irritable bowel syndrome (IBS) in particular.

METHOD

Prospective population-based birth cohort study of 4089 children born in Sweden 1994-1996. We analysed data from 2949 children with complete follow-up at 16 years (y) and no diagnosis of inflammatory bowel disease or coeliac disease at 12y or 16y. Asthma, rhinitis, eczema, and food hypersensitivity (FH) were assessed through questionnaires at 1-2y, 4y, 8y, 12y, and 16y. AP-FGIDs and IBS were assessed through questionnaires at 16y and defined according to the Rome III criteria. Associations between childhood allergy-related diseases and any AP-FGID and IBS and 16y respectively were examined using binomial generalized linear models with a log link function and described as relative risk with 95% confidence intervals.

RESULTS

The prevalence of any AP-FGID and IBS at 16y were 12.0% and 6.0% respectively. Eczema at 1-2y, 4y, and 8y, and FH at 12y and 16y were associated with an increased risk for any AP-FGID at 16y. Asthma and FH at 12y and 16y were associated with an increased risk for IBS at 16y. The relative risk for IBS at 16y increased with increasing number of concurrent allergy-related diseases at 16y, but linear trend for relative risk was only borderline statistically significant (P for trend = 0.05).

CONCLUSIONS

This prospective population-based study demonstrated positive associations between childhood allergy-related diseases and adolescent AP-FGIDs, including IBS, implicating shared pathophysiology among these disorders.

Passive Coping Associations With Self-Esteem and Health-Related Quality of Life in Youth With Inflammatory Bowel Disease

Pediatric patients with inflammatory bowel disease (IBD) may experience chronic stress related to disease symptoms and treatment, with negative consequences to their health-related quality of life (HRQOL). Lower HRQOL among pediatric patients with IBD has been associated with worse disease-related symptoms and psychological functioning, while higher HRQOL has been associated with more adaptive coping with disease symptoms and treatment. In addition, patients’ self-esteem may impact the selection and use of coping strategies through global cognitions about their abilities and perceived competence. The current study seeks to extend existing research on HRQOL in youth with IBD by examining cross-sectional associations among self-esteem and passive coping strategies. Youth ages 9–18 with IBD (n = 147) rated their HRQOL using a disease-specific measure, typical strategies used to cope with pain or GI symptoms, and their general self-esteem. Mediation analyses were performed using regression-based techniques and bootstrapping. Results indicated that greater self-esteem was positively associated with HRQOL but negatively associated with passive coping. Controlling for disease activity, age, and gender, significant indirect effects were found in the relation between self-esteem and HRQOL through passive coping. Multiple mediation analyses using the three passive coping subscales found that self-esteem was indirectly associated with HRQOL through its effects specifically on catastrophizing as a passive coping strategy. Results suggest that pediatric patients’ general self-esteem can impact their HRQOL through passive coping and specifically, maladaptive cognitions (e.g., catastrophizing). Interventions aimed at addressing both self-esteem and catastrophizing as a passive coping strategy may offer promise for improving HRQOL in youth with IBD.

Using Mediation Analysis to Understand How Treatments for Paediatric Pain Work: A Systematic Review and Recommendations for Future Research

Clinicians have an increasing number of evidence-based interventions to treat pain in youth. Mediation analysis offers a way of investigating how interventions work, by examining the extent to which an intermediate variable, or mediator, explains the effect of an intervention. This systematic review examined studies that used mediation analysis to investigate mechanisms of interventions on pain-relevant outcomes for youth (3–18 years) with acute or chronic pain, and provides recommendations for future mediation research in this field. We searched five electronic databases for clinical trials or observational longitudinal studies that included a comparison group and conducted mediation analyses of interventions on youth and assessed pain outcomes. We found six studies (N = 635), which included a total of 53 mediation models examining how interventions affect pain-relevant outcomes for youth. Five studies were secondary analyses of randomized controlled trials of psychological interventions for chronic pain; one was a longitudinal observational study of morphine for acute pain. The pain conditions studied were irritable bowel syndrome, functional abdominal pain, juvenile fibromyalgia, mixed chronic pain, and post-operative pain. Fourteen putative mediators were tested, of which three partially mediated treatment effect; seven did not significantly mediate treatment effect and four had mixed results. Methodological and reporting limitations were common. There are substantial gaps in the field with respect to investigating, and therefore understanding, how paediatric interventions work.