Posttraumatic stress disorder following childhood sexual and physical abuse: a study protocol for an 11-week randomised controlled trial comparing imaginal exposure and imagery rescripting

ABSTRACT

Background: There is a vast amount of evidence supporting the effectiveness of trauma-focused cognitive-behavioral therapy in treating posttraumatic stress disorder (PTSD). However, it remains unclear which specific treatment is most effective for patients with PTSD following childhood sexual and physical abuse (CSPA). Although Imaginal Exposure (IE) has proven highly effective in treating PTSD and is widely acknowledged as a standard method, Imagery Rescripting (IR) may be more suitable for CSPA-related PTSD. IR not only addresses fear but also targets other emotions and cognitions associated with childhood maladaptive schemas. Preliminary findings suggest lower drop-out rates for IR compared to IE, but no Randomized Controlled Trial (RCT) currently assesses the effectiveness of IR for CSPA-related PTSD.

Objective: This article presents a study protocol designed to investigate the optimal treatment (IE or IR) for individuals with CSPA-related PTSD and explore predictors of treatment success.

Method: In our study protocol, we suggest the inclusion of 173 patients (N = 64 in IR, N = 64 in IE, and N = 45 in the waitlist condition). The therapy procedures for both IE and IR will consist of 16 sessions lasting 90 min each, with treatment durations of 11 weeks. Measurements take place at baseline, at start of treatment, 11 weeks after the start of treatment (after 16 sessions) and at follow-up at 26 weeks after the last session. A mixed regression will be used to compare the three active conditions before and after measurement.

Results: This article serves as a study protocol. The results are not yet available but they will be presented in a subsequent article.

Conclusion: This study protocol outlines a RCT which will be the first to provide information on the effectiveness of IR versus IE versus a control group in CSPA-related PTSD.

Trial registration: Netherlands Trial Register NTR 4817. Registered 26 September 2014.

HIGHLIGHTS

• This study protocol is designed to enhance the clinical treatment for individuals (aged 18 and above) experiencing posttraumatic stress disorder (PTSD) resulting from childhood sexual and physical abuse (CSPA) occurring before the age of 16.

• Within this protocol, the efficacy of two PTSD interventions – Imagery Rescripting (IR) and Imaginal Exposure (IE) – will be systematically compared, both against each other and a control group.

• The secondary objective of this study protocol is to investigate potential predictors of treatment success, including factors such as tonic immobility, dissociation, heart rate variability, measures of autonomic arousal, personality disorders, and the quality of therapeutic alliance.

1. Introduction

Childhood sexual abuse and childhood physical abuse represent a concerning global issue, with prevalence rates remaining relatively stable over the past two decades. Worldwide, 3% to 17% of men and 8% to 31% of women have experienced sexual abuse before the age of 18 (Barth et al., 2013). In the Netherlands, 22% of women and 6% of men are estimated to have experienced this type of abuse before the age of 18 (Rutgers & Wijsen, 2017). A meta-analysis focusing on childhood maltreatment also reported high prevalence rates for physical abuse, estimating a global prevalence rate of 22.6% (Stoltenborgh et al., 2015).

Childhood sexual and physical abuse (CSPA) are strong predictors for mental and physical health problems later in life. Physical health symptoms that childhood sexual abuse is associated with include, gastrointestinal, gynaecological, cardiopulmonary, pain, greater likelihood of headache, panic-related symptoms and obesity symptoms (Irish et al., 2010), (Leserman, 2005). The long-term physical consequences of childhood physical abuse are also concerning, including a high risk of several physical symptoms, and medical diagnoses (Springer et al., 2007). Childhood sexual and physical abuse both have strong psychopathological health effects as well. These types of abuse are associated with an increased risk of borderline personality disorder (OR = 6.07) (Cutajar et al., 2010), alcohol- and/or drug-related disorders (OR between 1.01 and 8.9) (Cutajar et al., 2010; Kendler et al., 2000), as well as mood disorders (OR = 3.39) and suicide attempts (OR 7.97) (Perez-Fuentes et al., 2013). CSPA is also strongly linked to posttraumatic stress disorder (PTSD) (Odds Ratio (OR) 5.56) (Kessler et al., 1995). McLaughlin et al. (2017) propose that the increased salience of threat cues and amplified emotional responses to potential threats could be the potential mechanisms explaining how exposure to childhood maltreatment, such as sexual and physical abuse, increases the vulnerability to PTSD.

Overall, CSPA and its associated health problems lead to limited participation in society and high societal costs. In the United States alone, the annual economic burden of child maltreatment was $428 billion in 2015 (Peterson et al., 2018).

In the treatment guidelines for PTSD (National Institute for Health and Clinical Excellence [NICE], 2018) and according to the American Psychiatric Association practice guideline (American Psychological Association, 2017), the first-line psychological treatments for PTSD are trauma-focused cognitive behavioural therapy and Eye Movement Desensitisation and Reprocessing (EMDR). One of the common techniques used in trauma-focused cognitive behavioural therapy is Prolonged Exposure: this is a combination of Imaginal Exposure (IE) and exposure in vivo. These exposure-based techniques imply confrontation with the feared object, situation or activity. IE is based on confronting the patient with a feared mental Imagery from memory. The aim of this type of treatment is to dissolve the conditioned emotional response to traumatic stimuli by learning that the feared adverse outcomes will not occur during such events. This will eventually reduce or eliminate avoidance of feared situations and reduce the PTSD symptoms (Foa et al., 2007). Several studies found that several exposure treatment forms, like IE, appeared to be very effective in treating PTSD with a large overall effect size of Cohen’s d > 1.6 on primary outcome measures such as the Clinician-Administered PTSD scale (CAPS) and other PTSD severity scales (Bisson & Andrew, 2007). There is a majority of evidence supporting individual trauma-focused cognitive behavioural therapy, like IE, and EMDR, to be superior to non-trauma focused psychological treatment (Lewis et al., 2020). Based on various meta-analyses (Lewis et al., 2020; Oprel et al., 2021), it appears that in 40–70% of the patients a relatively short exposure-based treatment (9–12 sessions of 90 min) resulted in a considerable reduction of PTSD symptoms. However, compared to single onset and adult-onset PTSD, the amount of treatment studies for PTSD as a result of repeated and long-term child abuse in the immediate surroundings, is limited (Bisson & Andrew, 2013).

Moreover, the question arises whether standard treatment methods (trauma-focused cognitive behavioural therapy and EMDR) effectively target the fundamental processes contributing to the development of PTSD related to CSPA. Despite the established efficacy of these treatments, there are compelling reasons to explore alternative methods like Imagery Rescripting (IR) for the CSPA-related PTSD patients specifically. Layden et al. (1993) were one of the first to propose to use of imagery with rescripting to help a patient deal with traumatic memories and schema's/beliefs with a significant visual element. IR has evolved further as part of schema therapy, and was initially designed for treating personality disorders. However, an increasing body of research indicates that IR is also an effective treatment for axis 1 disorders, in particular PTSD (Arntz et al., 2007; Jung & Steil, 2013; Kindt et al., 2007; Raabe et al., 2015; Wild et al., 2008). IR can serve as an extension of or alternative to IE, functioning as the imagery component in the treatment of PTSD. But instead of focusing on fear extinction, IR additionally includes a change of the childhood maladaptive schemas into new adaptive schemas, thereby addressing other core cognitions and emotions such as guilt, shame, disgust, anger and sorrow (Arntz et al., 2007).

The following reasons provide support for the necessity of exploring alternative treatment approaches, like IR, specifically for treating CSPA-related PTSD.

1. End Result: A significant proportion of patients (ranging from 20% to 50%) who have completed exposure-based treatment, like IE, continue to meet the diagnostic criteria for PTSD. It is important to emphasise that this observation is applicable to PTSD resulting from various types of traumas and is not limited to PTSD stemming from childhood traumatisation (Bradley et al., 2005).

2. Exclusion criteria: Comorbidity is more the rule than the exception, especially in the CSPA-related PTSD patient group (Bisson & Andrew, 2013). However, it is worth noting that many studies tend to exclude comorbidity from their samples. In a review of 30 PTSD related studies, psychosis, alcohol abuse, suicidality, dissociative disorders, eating disorders, borderline personality disorders and bipolar disorders turned out to be an exclusion criterion in more than 60% of cases (Spinazzola et al., 2005).

3. Dropout rates: in recent RCTs of reasonably adequate power (N = 30 or more per condition), the drop-out rate for exposure-based treatment for PTSD was 36% (Cloitre et al., 2010). A meta-analysis comparing psychological therapies for chronic PTSD showed high overall dropout rates for trauma-focused cognitive behavioural therapy, which for the most part consisted of IE as primary treatment technique (Bisson & Andrew, 2013). Additionally, in a study comparing IE with a control group or waitlist, CSPA-related PTSD patients receiving IE treatment frequently dropped out of treatment prematurely, with dropout rates of 39% to 41%, compared to rates ranging between 9% and 26% in control groups consisting of supportive counselling or a waitlist (Cloitre et al., 2010; McDonagh et al., 2005). Overall, drop-out rates for IE treatment are generally high, with CSPA-related PTSD patients experiencing the highest drop-out rates. Previous research suggested that higher dropout rates were associated with a higher intensity of the exposure component (Becker et al., 2004). In one study, IE was compared to IE with the addition of IR to treat PTSD; the addition of IR reduced the dropout rate from 51% in (IE alone) to 25% (IE combined with IR) (Arntz et al., 2007).

4. Early Childhood Traumatisation and Tonic immobility: Previous studies showed that 37% to 52% of CSPA survivors report peritraumatic responses, such as analgesia, gross motor inhibition, eye closure and fixed or unfocused staring, collectively known as tonic immobility (Humphreys et al., 2010; Kleine et al., 2018). Tonic immobility is a state in which painful stimuli no longer lead to adequate responses. Tonic immobility can occur in response to the perception of immediate life-threat but extreme fear alone will not result in tonic immobility; it is the combination of fear, physical hindrance and no longer being able to escape (restraint) (Volchan et al., 2017). In CSPA related PTSD, 52% of the patients were found to report tonic immobility. And this type of PTSD was also correlated with poorer psychological functioning (more severe anxiety, depression and PTSD) (Humphreys et al., 2010). The relationship between tonic immobility and PTSD has been established in various studies. A meta-analytic study found out that tonic immobility mediates the influence of peritraumatic fear and observed inevitability on the severity of PTSD symptoms and that not the peritraumatic fear but the motoric tonic immobility was found to be the predictor of severity of the PTSD symptoms (Coimbra et al., 2023). Tonic immobility is accompanied by a suppression of the autonomic responses. Since autonomic arousal is required for adequate fear extinction, it could be assumed that patients experiencing tonic immobility show decreased autonomic arousal during exposure to trauma cues and would therefore benefit less from IE. Two studies have already shown poorer recovery from PTSD in patients with higher peritraumatic tonic immobility after pharmacological treatment (Coimbra et al., 2023; Fiszman et al., 2008). To our knowledge there is no study to date that researched the recovery from PTSD in patients with high peritraumatic tonic immobility comparing IE to IR treatment.

5. Focus on fear reduction: IE focuses more specifically on reduction of fear. Since dysfunctional schemas and emotions like guilt, shame, disgust, anger and sorrow are prevalent in the CSPA-related PTSD patient population, it is questioned whether IE is the most effective treatment for this specific population.

2. Research questions

Given the reasons above and the dysfunctional schemas and emotions that are prevalent in this specific population, we hypothesise that IR is more effective than IE for reducing PTSD symptoms in patients with CSPA-related PTSD. Additionally, we predict an improvement in overall psychopathology for both groups after treatment, with the IR group experiencing a greater decrease in psychopathology scores compared to the IE group. Similarly, we expect a reduction in depressive symptoms overall, with IR resulting in fewer depressive symptoms compared to IE. We expect IR to be more effective, because IR targets the schemas and memory traces within semantic memory, resulting in a more comprehensive change, whereas IE primarily addresses memories stored in the episodic memory (Arntz et al., 2007).

We also expect less dropout in the IR group because in IR, only a short exposure time is necessary. Treatment dropout is expected to be a lot lower than the average 51% drop-out rate for IE treatment (Cloitre et al., 2010) and also lower than the 25% drop-out rate that was seen in a previous study where IR was added to IE (Arntz et al., 2007). We expect that the shorter exposure time that is needed in IR, might be easier to maintain and might lead patients to less frequently dropout. The shorter exposure time might also work better in patients with CSPA-related PTSD because they are more likely to have tonic immobility. In order to accomplish fear extinction, autonomic arousal is essential, and tonic immobility is linked to the suppression of autonomic responses. We expect the patients to experience less tonic immobility with IR compared to IE. Despite the fact that tonic immobility and dissociation play a central role in CSPA-related PTSD, psychophysiological studies on PTSD have not yet included these aspects as predictors. We expect that higher scores of tonic immobility, dissociating and autonomic arousal (higher heart rate variability), will result in bigger differences in the effectiveness between groups, with IR being more effective than IE for people that score high on these items.

In conclusion, in this study protocol we propose a RCT where the main objective is to compare the effectiveness of IR versus IE for the treatment of patients (18 years and older) with PTSD following CSPA (with onset before the age of 16 years). To exclude time-effect bias, we added a (waiting list) control group. Besides, we will also take into account possible predictors like tonic immobility, dissociation and autonomic arousal (heart rate variability). We anticipate both IE and IR to yield significant results in reducing PTSD symptoms, leading to fewer individuals meeting diagnostic PTSD criteria, reduced overall psychopathology, and diminished depressive symptoms at post-treatment. However, we expect IR to demonstrate superior outcomes and lower dropout rates compared to IE across all measures. Furthermore, we predict that higher scores in tonic immobility, dissociation, and autonomic arousal will result in greater differences in effectiveness between the two groups, with IR proving to be more effective.

3. Methods

3.1. Participants

A total of 173 participants, all diagnosed with a primary diagnosis of PTSD stemming from CSPA, are included. Participants were notified about the research after referral. Upon expressing interest, screening interviews were administered (see screening measurements). Random assignment to one of three different conditions occurred only for individuals who met the inclusion criteria, did not meet the exclusion criteria, and had provided signed informed consent. They were randomly assigned to one of the three conditions. A power-analysis has been done to calculate the sample size, see below. To read more about the recruitment, see procedure.

3.2. Recruitment of patients

General practitioners could refer patients to the Psychotherapy & Movement institution, a relatively small outpatient treatment facility located in the centre of Amsterdam. This institution is recognised for its expertise in addressing trauma and personality disorders, leading general practitioners throughout Amsterdam to specifically refer their patients for trauma treatment. Following an initial assessment, potentially eligible patients were informed about the ongoing study and provided with an informational brochure. Details about the study were also available on the practice's website. Individuals expressing interest in participation were scheduled for an appointment with an independent research assistant who conducted the measures for T0, the inclusion measurement. General characteristics and other inclusion and exclusion criteria were asked out by the research assistant. Once T0 was concluded, and if the patient met the inclusion criteria, the clinical psychologist extended an invitation to participate in the study and sign the informed consent.

3.3. Inclusion criteria

The primary inclusion criterion was a primary diagnosis of PTSD according to DSM-5, following sexual and physical abuse before the age of 16 according to the Interview for Traumatic Events in Childhood (ITEC) (Lobbestael et al., 2009). Sexual abuse was defined as one or more episodes of sexual contact against the victim’s will. Physical abuse was defined as one or more episodes of intentional hitting, punching, kicking, cutting, pinching, hair pulling or strong threatening to perform one of these events against the victim’s will. The perpetrator was a person that lived in the participant’s direct social environment, was at least five years older than the victim and had a role as a figure of authority.

Psychiatric comorbidity was allowed. Patients with the following comorbid psychiatric disorders were included: depressive disorder, anxiety disorder, attention deficit-hyperactivity disorder, dissociative symptoms, reactive psychotic episodes in the context of PTSD, substance dependence (drugs and/or alcohol), borderline personality disorder and cluster C personality disorders. If a participant used Selective Serotonin Re-uptake Inhibitors (SSRI), the dosage needed to be stable for at least three months before inclusion. Benzodiazepines were allowed if patients had a stable dosage of a maximum of 30 mg oxazepam equivalents for at least three months.

3.4. Exclusion criteria

During the screening assessment at T0, exclusion criteria were asked out by the independent research assistant. Participants lacking adequate proficiency in both verbal and written Dutch were excluded, as well as patients who were receiving additional treatment for other mental disorders. Furthermore, due to the absence of a crisis intervention service and a psychiatrist, the following exclusion criteria were established: psychotic disorders (or a history thereof), present suicide risk (no suicide attempts must have taken place in the three months prior to inclusion), actual self-wounding behaviour, dissociative disorders (but dissociative symptoms like depersonalisation, derealisation or dissociative amnesia were not considered as grounds for exclusion) and mental retardation. Usage of psychopharmacological medication other than SSRI and benzodiazepines was not allowed. Participants using alternative psychopharmacological medications were excluded to avoid potential bias in treatment outcomes linked to medication use. However, we did not exclude the use of SSRIs and benzodiazepines due to their widespread usage in this particular population. Nonetheless, we only included patients whose dosage had remained stable for a minimum of three months. Additionally, a person who had substantial financial issues, no single supportive figures, problems with the Ministry of Justice, ongoing physical or sexual abuse and/or was homeless, was excluded. The selected exclusion criteria were designed to prioritise the safety, well-being, and therapeutic readiness of participants. Individuals confronting substantial stressors such as financial challenges, involvement in the justice system, or inadequate support systems may not possess the emotional or psychological readiness necessary to engage effectively in trauma treatment.

3.5. Therapists and treatment adherence

All seven therapists participating in this study are experienced cognitive behavioural psychotherapists that have been well trained in cognitive behavioural therapy (CBT) (with a minimum of 150 h of schooling in CBT accredited by the Dutch CBT association) and that received specific schooling in the protocols of IR and IE. The group of therapists encompassed of therapist who were still in training for their post-master degrees, all the way to those with doctoral degrees and over 30 years of experience. Four hours of group supervision was provided each month by experts in the target treatments (two hours IE and two hours IR). Additional supervision by telephone or email was provided on request. To verify treatment adherence, all IE and IR sessions were audio/video-recorded and a random selection (10%) was taken for independent reviewing by trained raters who were blind to treatment outcome.

3.6. Treatment

In this study, two psychotherapeutic interventions will be compared, IE and IR. The IE protocol that was applied in this study is the standard protocol that is described in the Dutch Multidisciplinary Guideline for Anxiety disorders (Keijsers et al., 2011) as first choice treatment and is based on the Prolonged exposure protocol by Dancu and Foa (1992; Foa et al., 1997). Smucker and Niederee described a two-phase IR procedure for the treatment of childhood abuse-related PTSD in 1995, namely IRRT (Smucker & Niederee, 1995). Arntz and Weertman (1999) added a third phase to this protocol for the treatment of traumatic childhood memories. In this study, the three-phase IR protocol was used.

Both IR and IE are manualized protocolled treatments consisting of 16 face-to-face sessions of 90 min. During the first five weeks, the treatment frequency was twice a week, and during the final six weeks the frequency was once a week. We aimed for a total treatment period of 11 weeks. In case the patient and/or therapist had to miss a session unexpectedly, a prolongation of this interval was allowed up to a maximum of 14 weeks. After the 16th session, the patients who had been treated in the IR or IE condition got a treatment break of 26 weeks. In this period, the patients received four monitoring sessions evaluating their clinical status. These brief monitoring sessions, which were aimed to keep an eye on the patient's well-being, did not involve any form of therapy.

After the 26 week-follow-up period, treatment as usual was started, if indicated. The control group did not receive any treatment in the first 11-weeks. After this period, patients in this group received treatment as usual.

3.7. Measurement

Measurements were taken at four moments. T0 was the time point of inclusion measurement and contained four diagnostic clinical interviews (see Table 1). The time points thereafter were fixed intervals: T1 (one week after T0 and directly before start of treatment), T2 (week 11, directly post-treatment) and T3 (26 weeks after T2). During these three time points, self-administered questionnaires were filled in online. All the assessment scales were filled in at T1, T2 and T3. After T2, a break of 26 weeks took place. After T3 patients would either have successfully completed treatment, or if necessary, treatment as usual was offered. Table 1 provides an overview of all measurements (including diagnostic interviews, questionnaires and psychophysiological measures) at each time point.

Table 1.

Fixed time intervals with an overview of all measurements.

	Measurement method	With the aim to measure:	T0 screening	T1 session 1	T2 Session 16	T3 (26 weeks after T2)
Primary outcome	Klinisch Interview PTSS (KIP)	A PTSD diagnosis with a PTSD diagnostic interview	x		x	x
	Posttraumatic Diagnostic Scale (PDS)	PTSD symptoms		x	x	x
Secondary outcome	Brief Symptom Inventor (BSI)	General psychopathology		x	x	x
	Beck Depression Inventor (BDI-II)	Depression		x	x	x
Predictors	Dissociation trait Questionnaire (DIS-Q)	Dissociation		x	x	x
	Tonic Immobility Scal (TIS)	Tonic immobility		x	x	x
	Work Alliance Inventory Therapist (WAI-T)	Therapeutic alliance (therapist)		x (3 weeks after T1)
	Work Alliance Inventory Patient (WAI-P)	Therapeutic alliance (patient)		x (3 weeks after T1)
	Heart rate variabilit (HRV) experiment	Autonomic arousal		x	x

3.7.1. General patient characteristics

We have composed a biographical semi-structured interview, asking out demographic characteristics, such as age, sex, education, employment, marital and relationship status, children and religion. The history of psychological and somatic diseases, their duration (including duration of PTSD symptoms) and treatment status was also established. This interview was conducted at T0 by trained and experienced therapists.

3.7.1.1. Inclusion measurement

The CAPS (Weathers et al., 2001) is a structured interview widely used to assess and diagnose post-traumatic stress disorder (PTSD). The psychometric properties of the CAPS are well-established, and it has been considered a gold standard for PTSD assessment. The interview consists of 30 items, of which 25 are divided over the PTSD classification criteria, two for rating guilt feelings and three for dissociative symptoms. The CAPS has a strong interrater reliability (kappa = 0.78 to 1.00 depending on the scoring rule) and a good test-retest reliability (kappa  = 0.83) and it correlates well with other established measures of PTSD. The total severity score of the CAPS demonstrates high internal consistency (α = .88) and interrater reliability (ICC = .91) and good test–retest reliability (ICC = .78). For the total severity score, a cut-off score of 60 is used to determine if a patient is included in the study (Weathers et al., 2001). In this study, the KIP (‘Klinisch Interview PTSS’) (Hovens et al., 2002), which is the validated Dutch translation of CAPS, was used to measure the severity of PTSD symptoms. The KIP has equally good internal consistency and validity (Hovens et al., 2002; Weathers et al., 2001). The interview was used to asses a possible PTSD classification.

To determine potential comorbidity on DSM Axis I or II, the independent research assistant performed the Mini International Neuropsychiatric Interview plus (MINI plus) (Sheehan et al., 1998) and Structured Clinical Interview for personality disorders (SCID-II) (First & Gibbon, 2004) The MINI Plus is a structured diagnostic interview compatible with DSM- IV and ICD-10 criteria which is suitable to asses the classification of Psychotic and Mood DSM-IV Disorders. The MINI-Plus has good psychometric properties and is widely used to support diagnostics in psychiatry. The SCID-II also has adequate to good interrater reliability and an excellent overall agreement on personality disorders (kappa = 0.80) (Lobbestael et al., 2011).

The Interview for Traumatic Events in Childhood (ITEC) (Lobbestael et al., 2009), a retrospective trauma interview, was used to examine the association between childhood abuse and psychopathology. Patients answered a set of standardised questions concerning five types of childhood maltreatment (sexual-, physical- and emotional abuse, and emotional- and physical neglect). These subscales have good internal consistency, except for the physical neglect subscale, and an excellent inter-rater reliability. All subscales have a high convergent and criterion validity when compared to existing measures.

3.8. Primary outcome measures

3.8.1. PTSD diagnosis

The Posttraumatic Diagnostic Scale (PDS) is a self-report diagnostic instrument consisting of 49 items based on DSM-IV criteria of PTSD (Foa, 1995). The scale has been validated on samples aged 18–65 and is demonstrating strong overall validity. It exhibits a strong face validity, as its items directly reflect the experience of PTSD with high internal consistency (coefficient alpha of 0.92). The test-retest reliability for diagnosing PTSD, is also highly satisfactory (kappa = 0.74) over a 2–3-week period. Additionally, the correlation between test-retest using symptom severity scores is also highly significant (0.83). The scale has also shown an 82% agreement between diagnosis using the PDS and the Structured Clinical Interview for DSM (McCarthy, 2008). The symptom severity scores are used to measure the effectiveness of each treatment.

3.9. Secondary outcome measures

3.9.1. Depressive symptoms

The Beck Depression Inventory (BDI-II) (Beck et al., 1996) was used to measure the presence and severity of depressive symptoms. The BDI-II demonstrates excellent concurrent validity and it has strong correlations with other depression measures. It shows a high internal consistency (coefficient alpha of 0.9), a commendable test-retest reliability (ranging between kappa = 0.73 to 0.96) and it displays noteworthy sensitivity and specificity, effectively distinguishing individuals with depression from those without (Wang & Gorenstein, 2013). The questionnaire consists of 21 questions assessing various depression symptoms. The BDI-II provides normative data for score interpretation. A typical score interpretation include: Minimal depression (0–13), Mild depression (14–19), Moderate depression (20–28) and Severe depression (29–63). The BDI-II has been validated in Dutch and shows similar validity and reliability scores (Beck et al., 2002). We will compare BDI-II scores across treatment conditions to assess treatment effectiveness and see if this differs between IE and IR specifically.

3.9.2. General psychopathology

The Brief Symptom Inventory (BSI) was used (Derogatis & Melisaratos, 1983) as an outcome measure for general psychopathology. BSI is a self-report multidimensional psychological and somatic symptom inventory consisting of 53 items. The BSI includes subscales that assess different symptom dimensions, such as depression, anxiety, and somatisation. Elevated scores on specific subscales may indicate heightened distress in those particular areas. The Global Severity Index is a summary score that reflects overall psychological distress. With higher GSI scores indicating higher levels of distress. The BSI demonstrates strong concurrent validity and it has a high construct validity with a good internal consistency (coefficient alpha of .74 (Somatisation), .84 (Depression), .79 (Anxiety), and .89 (GSI)). When the BSI was developed, the author estimated a test-retest reliability ranging from kappa = .68 to .84 on the symptom dimension over an unspecified time interval in a nonpatient sample. GSI test-retest was estimated at kappa = .90. The BSI provides normative data which allows for the comparison of individual scores with those of a relevant reference group. The version used in this study has been validated in Dutch (de Beurs, 2006). The Dutch version exhibits even higher coefficient alphas for internal consistency on certain scales compared to the American BSI. Test-retest reliability is comparable to that of the American version, with kappa values ranging from .71 to .89. We will compare BSI scores across treatment conditions to assess treatment effectiveness and see if this differs between IE and IR specifically.

3.10. Predictors

3.10.1. Tonic immobility

The Tonic Immobility Scale (TIS) is a 10-item self-inventory scale (Forsyth et al., 2000) that has been validated in Dutch. The questionnaire is composed of three items related to fear and seven items belong to the immobility factor. The items involve possible reactions during an experience of forced acts of sexual or physical abuse without the consent of the victim. A high tonic immobility might make IE treatment less effective than IR. In the study we would like to see if the level of TI could be seen as a predictor in treatment success.

3.10.2. Dissociation

To measure dissociative symptoms, the Dissociation trait Questionnaire (DIS-Q) will be used (Vanderlinden et al., 1993). This is a 63-item scale developed in the Netherlands. Items can be scored from 1–5. The severity of dissociative symptoms including identity confusion, loss of control, amnesia and absorption will be measured. The DIS-Q has excellent internal consistency (Cronbach alfa – 0.96) and is able to distinguish well between dissociative and nondissociatieve patients. It is expected that patients that have more dissociative states, might benefit more from IR compared to IE than patients with no dissociative states. To test this hypothesis, dissociation will be taken into account as a predictor.

3.10.3. HRV (heart rate variability)

Each patient has undergone heart rate measurements using the VU-AMS device and VU-DAMS software (De Geus et al., 1995) The difference in physiological stress response will be measured as a predictor of treatment success. In a computer-programmed experiment, each patient listened to a pre-composed neutral, stressful, and traumatic script (i.e. three different scripts) and answered questions concerning subjective units of distress and the extent of dissociation after each script (see appendix 1). HRV was used to calculate the amount of autonomic arousal. Autonomic arousal levels and tonic immobility are utilised to test if these can predict which treatment would be most beneficial for the patient.

3.11. Process measures

3.11.1. Therapeutic alliance

After the third session of the IE and IR condition, the 36-item Work Alliance Inventory (WAI-T and WAI-P) (Horvath & Greenberg, 1989) was filled in to investigate the different effects of each condition on the quality of the work alliance between patient and therapist, including goal, task, and bond components. The therapeutic alliance will be used to determine if this is a necessity for a successful treatment and if differences in therapeutic alliance will differ between the IE and IR condition.

4. Procedure

See Figure 1 for a flowchart of the study design. The Medical Ethics Committee of the Academic Medical Centre in Amsterdam has approved the study protocol (registration number 2014_098). Data collection started in 2018 and was completed in 2022.

Figure 1.

Flowchart of study design.

4.1. Randomisation and blinding

One independent research assistant randomly assigned each participant to one of the three conditions, using a computer-generated randomisation table (Moher et al., 2010). Another independent research assistant performed all the measures for inclusion (T0) and T1, T2 and T3. The therapists were not informed about the results of the data. Group allocation was impossible to be blind, because both therapists and patients could notice which condition had been performed.

5. Power-analysis

A power-analysis was done to calculate the sample size of each condition. This study contains three conditions: IE, IR and waitlist. Three comparisons will be analysed: IE versus the waitlist condition, IR versus the waitlist condition and IE versus IR.

To calculate the sample size, we took into account the issue of multiple tests (one primary outcome measure and two secondary outcome measures). We determined the critical alpha using the False Discovery Rate procedure adjustment. With a total two-sided alpha of .05, this translates to an alpha of .024 per test. Considering a medium effect size for the trend (f = .25) and alpha = .024 (two-sided), with 80% power, a total sample size of 156 is deemed necessary.

Additionally, we have based our sample size on previous studies (Arntz et al., 2007; Griffin et al., 1997; Grunert et al., 2007; Jung & Steil, 2013; Lindauer et al., 2006; Powers et al., 2010). Based on these studies we expect an effect size of 0.6 between IE and the waitlist condition for the primary outcome measure the Posttraumatic Stress Diagnostic Scale (PDS) (Lima et al., 2010). With a two-sided alpha of 0.05 and a beta of 0.8, this results in 45 patients per condition. For the comparison between IE and IR, we expect an effect size of 0.5, based on the same study as above. With a two-sided alpha of 0.05 and a beta of 0.8, 64 patients need to be included for both the IE and IR condition. We hypothesise that when two active treatments result in a Cohen’s d effect size of 0.5, the effect size in a comparison between active and waitlist condition will be higher. It should be noted that in practical application, the inclusion of covariates that diminish error variance will further augment the power of the analysis.

We have also taken into account the potential dropout rates across all conditions. In a systematic review and meta-analysis comparing dropout percentages from psychological therapies for PTSD in adults, dropout rates were observed to be 11% for waitlist groups and 22% for exposure-based treatments like Imaginal Exposure (IE) (Lewis et al., 2020). Considering significantly lower dropout rates for the Imagery Rescripting (IR) group compared to IE, as demonstrated by Arntz et al. (2007), we can anticipate overall dropout rates ranging between 11% and 22%. This implies that we require a minimum of 173 patients and a maximum of 190.

All participants were randomly assigned to one of the three conditions. Their measurements will only be included in the analysis after completion of all measurements and treatment sessions up to T2. In the event of patient drop-out during treatment, if patients agreed to complete T2 measurements, those measurements will not be included in the primary analysis. For the waitlist condition this means that their data is only included in the main analysis when they completed all measurements up until T2; after which treatment as usual started.

Taking into account both calculations, the use of covariates and the dropout rates, we have included a total of 173 patients. These were randomly allocated to one of the following three conditions: Waiting List (N = 45), IE (N = 64) and IR (N = 64).

6. Statistical analysis

The main research question will be examined through mixed regression (ANOVA), specifically comparing the PTSD symptom severity scores (utilising the PDS) across the three active conditions before and after measurement. It is assumed that there is a medium effect size for the linear trend, with the conditions ordered as IR < IE < Waitlist. This assumption is drawn from the findings of Arntz et al. (2007), who reported an average effect size of Cohen's d = .55 favouring IR over IE in several measures. The same mixed regression (ANOVA) analysis will be conducted for the secondary outcomes where the existence and severity of depressive symptoms (assessed with the BDI-II) and general psychopathology (evaluated with the BSI) are compared across the active conditions before and after treatment.

Predictors include severity in Axis II (borderline symptoms and avoidant symptoms), tonic immobility (self-report and tonic immobility as discrepancy between low physiology and subjective anxiety), dissociation, alcohol and medication use, severity of trauma, therapeutic relationship, and heart rate variability. We expect that patients with a high tonic immobility will have a better effect in the IR condition than in the IE condition, because in those treatment conditions the tonic immobility response is directly influenced. We expect the difference between conditions will be less pronounced in patients with a low tonic immobility.

7. Discussion

The severe global health problem of PTSD following CSPA, its high disease burden, the high drop-out rate of existing treatment methods for PTSD and the relatively underreported state of CSPA victims in PTSD treatment outcomes studies, underline the need for this RCT. This study will be the first to compare the effectiveness of IR versus IE for the treatment of patients with CSPA-related PTSD. There has been some evidence that IR can be an effective treatment for adult-onset PTSD, however there is very few studies available to support its use in a population of chronic and severe PTSD. The strength of this RCT lies in its inclusion of a homogeneous patient population comprising victims of childhood sexual and physical abuse, and its use of a three-arm study design that compares IE, IR, and a control group to minimise bias related to the passage of time.

In addition to being the first study to compare the effectiveness of IE versus IR as a treatment for CSPA-related PTSD, there are several other strengths to this research. First of all, both treatments consist of 16 sessions lasting 90 min each, ensuring a reliable comparison. Additionally, our study includes a more representative group of patients, taking into account comorbidity, which improves the generalizability of the results to the general practice. Another strength is our significant sample size of N = 173, which is a relatively large sample size in the context of trauma studies. The high power of our study reduces the likelihood of sampling errors and makes our results more credible and representative. Furthermore, we have also considered tonic immobility, dissociation, and autonomic arousal as potential treatment predictors, as these are commonly experienced by individuals with CSPA-related PTSD. By examining these factors, we aim to gain a better understanding of why IE may not be the most suitable treatment option for this specific group, providing valuable insights for future therapeutic decisions.

There are several limitations to the current study. Firstly, our exclusion criteria impose limitations on the study. Specifically, we only focus on patients with repeated CSPA-related PTSD and exclude those who have experienced only one type of childhood trauma or experienced both types of traumas only once. This limitation hinders our ability to determine the relative effectiveness of IE and IR in treating each specific type of trauma and its generalizability to people that have not experienced childhood traumas repeatedly. Furthermore, we have only included patients who experienced the abuse by someone at least five years older than them, which excludes cases such as abuse in a brother-sister relationship with less than a five-year age difference. As mentioned before, patients with dissociative disorders were excluded from the study. Nevertheless, it is important to note that mild dissociative symptoms such as depersonalisation, derealisation, or dissociative amnesia were not considered as grounds for exclusion. Many patients with dissociative disorders have also experienced CSPA-related trauma. This exclusion restricts the generalizability of our findings and raises questions about whether IR would be a more effective treatment for individuals with dissociative disorders. Furthermore, it is important to note that our study solely involves patients receiving outpatient care. This limitation should be acknowledged as it may impact the generalizability of the findings to individuals with more severe mental health conditions or those requiring specialised inpatient care. Future studies should aim to include a broader range of participants to provide a more comprehensive understanding of the effects of the treatment approaches in different settings and populations.

Secondly, there are certain limitations regarding the therapeutic aspects of the study. While the therapists involved were trained and experienced, there were variations in their years of experience and educational backgrounds. Although all therapists possessed at least a Master’s degree in Psychology and a minimum of 150 h of CBT schooling accredited by the Dutch CBT association, there was considerable variation in their years of experience. It is important to note that therapists with different levels of education and experience may employ distinct approaches and possess varying skill sets, which could potentially affect the effectiveness of the treatment provided. To limit these differences, we attempted to ensure treatment adherence by conducting independent reviews of recorded sessions and providing regular supervision. Additionally, three weeks after starting treatment, patients were administered the WAI-T and WAI-P questionnaires to measure the quality of the work alliance between patient and therapist. While we choose to measure the work alliance only once after three weeks, considering the potential benefits, future studies should consider assessing it during each session while using a shorter questionnaire such as the WAV-12. It is important to note that our measurement at the third week of treatment may not yield significant results, as it may take patients longer to develop a strong working alliance.

Finally, we would like to acknowledge that there could have been more predictors and outcome measures considered in our study. We were careful not to overload the patients with excessive questionnaires and measurements, so we had to limit the number included. In future research, it would be beneficial to incorporate the Difficulties in Emotion Regulation Scale (DERS) as an additional measure, as we expect that IR would not only reduce fear but also impact other emotions. By assessing the DERS at the beginning and end of treatment, we would be able to gain more insights into changes in emotion regulation among PTSD patients receiving either IE or IR. Furthermore, it would be interesting to include the Adult Attachment Interview (AAI) (George et al., 1985) as another predictor. This would allow for a better understanding of which specific treatment would be most beneficial for each individual patient based on their level of attachment.

Concluding, the results of this study will be the first to compare IE to IR in a CPSA-related PTSD population, while also researching possible treatment predictors. We hope the results of this study will support the use of IR in a population of chronic and severe PTSD and result in better treatment outcome and lower drop-out rates.

Ethics approval and consent to participate

Please find attached the statement on ethics approval and consent.

Name of committee: ‘Medisch Ethische Toetsings Commissie AMC (Academic Medical Center)’.

Committee reference number: 2014_098#B2014727.

Study reference number: NL47783.018.14.

Appendices.

Appendix 1

Computer-based psychophysiological assessment.

Measurement of autonomic values during three written scripts including one that is based on the event that caused PTSD.

During this computer-based psychophysiological assessment the heart rate variability (HRV) and skin conductance level (SCL) are measured while the patient is hearing three written scripts through a headphone.

HRV and SCL are measured using the ‘VU-AMS device’ [http://www.vu-ams.nl] and for the computer based experiment software applications ‘VU-DAMS software’ [http://www.vu-ams.nl/support/downloads/software/] and ‘Opensesame’ [https://www.opensesame.com] are used.

The practice and stressful scripts are the same for all patients and the trauma script is based on the patients’ most traumatic experience involving sexual and/or physical abuse.

Before the start of the assessment, we will give the patient instructions on the composition.

First, a baseline measurement will be done. The first script is a ‘practice script’, which has the objective to train the imaginal experience assuring that the following scripts are re-experienced as vividly as possible. In the first script the patient is imagining making a walk in the park while noticing the leaves moving in the wind and ducks swimming in the pond. When the event that is thought to have caused the PTSD happened in a park, we will account for this by changing the script.

Second, the patient is hearing a neutral script, which has the objective to measure the baseline HRV and SCL during a script that generally does not lead to an emotional response. Though we expect that some patients with severe PTSD might be triggered by certain parts of this script. During this script the patient is imagining watching a familiar television show and is walking to the kitchen to take a drink out of fridge.

The last script is a part of the traumatic event thought to have caused the PTSD. We ask all 173 patients to write down the course of the most traumatic event including personal feelings, thoughts and sensory information. Then, we will create a summary of this and an independent person will record the text that is part of the experiment.

To make sure possible alterations in autonomic values do not influence the values during the next script, we show a video of animals in a natural reserve between the first and second script, and a video of a fishes and a coral reef between the second and third script.

After each script there is a silent phase in which the patient is instructed to imprint the script. Then a questionnaire will follow in the computer-based assessment. In the questionnaire the patient is asked to answer if the following emotions and feelings are present on a 10-point scale: anxiety, feeling paralysed, pleasure, shame, watchful, happy, guilty, angry, disgust, grief, tonic immobility. In addition the patient is asked questions about the degree of imagination and avoidance.

After the last questionnaire the assessment ends and the VU-AMS device will be disconnected.

Appendix 2

Description of the IE and IR protocols used

IE:

During IE, the patient re-experiences the traumatic situation in their imagination under supervision of the therapist. The memory will be retrieved as truthfully and vividly as possible. The patient closes their eyes and the therapist explains that it is important that the patient describes the trauma in as much detail as possible using the present tense, as though it is happening in the here and now. It is also important that the story is told in the first person. During the act of re-experiencing, the therapist will occasionally ask the patient how high their level of fear is on a scale of 1–100. The exposure itself lasts 60 min without a break (the total length of a session is 90 min). If the patient completes their story in less than 60 min, they will be asked to re-tell the story. The therapist will encourage the patient to pay attention to the sensorial information (hearing, feeling, seeing, smelling) so that the recollection is retrieved in as much detail as possible. For the sake of habituation, it is important that the patient does not pause or suppress memories while telling the story, even though they may be painful. The therapist will then encourage the patient to continue, while noting the instances of avoidance, and makes sure that attention is paid to these ‘hot spots’ of the traumatic memory in the following session. In the follow-up discussion of the exposure exercise (lasting 10–15 min), the patient gives an indication of how the session went, what fell below expectations and what exceeded expectations, and any questions are answered. At the same time, the course of the fear score and the cognitive changes that are set in motion by the exposure are discussed. Additionally, attention is paid to the new meaning that the traumatic event acquires, the role that the patient played, and understanding the event in the context.

Because there are many traumatic events per patient, the therapist creates a hierarchy of all the traumatic events categorised under sexual, physical and emotional abuse per perpetrator (a separate SUD score for each event). In every session, the patient chooses a different traumatic situation. Preferably, the therapist starts with the events that produce the most fear in the patient. Where this is not possible, an event is chosen in collaboration with the patient. In session 1, the therapist provides information about the treatment and motivates the patient for the exposure treatment. The therapist decides with the patient which traumatic events are important and the sequence in which they will be presented. The patient then gives a brief explanation of the traumatic events. At the same time, a decision is made regarding which traumatic event is to be discussed at the start of session 2. The patient must bring along audio-recording equipment because the exposure session will be recorded so that the patient can listen to it at home. In session 2, the therapist encourages the patient to start with the traumatic situation which he/she has the most re-experiences and nightmares about. Session 3 follows in principle the same pattern as session 2 but the therapist will go into the traumatic event in increasingly more depth. It is not necessarily required to choose a new situation from the hierarchy for each session; this depends on the fear scores. In all the other sessions, the therapist repeats this procedure broadly.

IR:

Within an IR session, the time spent imagining traumatic events is as short as possible. The patient is able to intervene from the current perspective and implement his/her needs, i.e. by expressing grief or anger regarding the perpetrator or perpetrators. In the first session, just as with IE, a hierarchy is created of all the traumatic events, and an explanation is given regarding PTSD complaints and survival mechanisms, and about the working of IR itself. In the first phase of IR, the therapist will only very briefly (at most one minute) get the patient to imagine the affectively charged memory through questions about sensory experiences, with the aim of getting the patient to experience the event from the perspective of the patient as a child. If the first emotions are evident, this is sufficient and the therapist will say something like: ‘OK, let’s stop there because we now know enough and we don’t want to repeat the whole situation’. In contrast to IE then, IR does not concern exposure. The therapist continues through to phase 2 while the patient keeps their eyes closed. The situation from phase 1 is assessed by the patient from the perspective of the adult, if necessary, with the assistance of the therapist, who may also be seated in the view of the patient as support for the adult. The adult then intervenes (reparenting) by for example talking to the perpetrator in an angry tone and ordering the perpetrator to move away from the child. At the same time, attention is paid to what the child needs further, for example, comforting or safety. The therapist encourages the adult to do what the adult thinks is necessary. The aim of the third phase is to determine whether the child has actually received what it needed and to integrate the new experiences more tightly with the (childhood) schemas. The patient continues to remain seated with the eyes closed and the therapist asks and helps the patient to experience the intervention as a child, and at the same time, the patient is encouraged to provide supplementary interventions as an adult. The therapist does not stop asking questions until all the needs of the child have been met. In this way, the patient is able to integrate new insights into the self-image and not only remove the threat but the patient is also encourages to acknowledge other needs that have been long suppressed.

Both IR and IE are manualized protocolled treatments consisting of 16 face-to-face sessions of 90 min in a period of 11 weeks. During the first five weeks, the treatment frequency is twice a week, and during the final six weeks the frequency is once a week.

Funding Statement

Psychotherapy & Movement in Amsterdam has been granted a subsidy from Stichting tot Steun VCVGZ.

Open Scholarship

This article has earned the Center for Open Science badges for Open Data and Open Materials through Open Practices Disclosure. The data and materials are openly accessible at https://doi.org/10.1080/20008066.2024.2358683.

Authors’ contributions

PMdJ and MTCvH contributed to the design of this study, developed the intervention of this study and coordinated the recruitment of patients and the data collection. PMdJ and MTCvH are responsible for the overall design and supervision, and wrote and approved the final version of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

Not applicable, because this article concerns a ‘Study Protocol’.