Exposure-Based Treatment for Undifferentiated Somatic Symptom Disorder

Single-Arm Feasibility Study of Exposure-Based Treatment for Undifferentiated Somatic Symptom Disorder

Status

Completed

Phases

Study type

Interventional

Source

ClinicalTrials.gov

Registry ID

NCT04511286

Acronym

SOMEX0

Enrollment

Registered

2020-08-13

Start date

2020-09-11

Completion date

2021-02-24

Last updated

2025-03-19

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Somatic Symptom Disorder

Keywords

Exposure, Feasibility

Brief summary

This study investigates the feasibility of a general exposure-based treatment protocol that is intended to work for a large variety of patient groups with a clinically significant preoccupation with physical symptoms. This is a prospective single-group study based at Karolinska Institutet, Stockholm, Sweden, where 40 adults with DSM-5 somatic symptom disorder are enrolled in 8 weeks of therapist-guided exposure-based treatment via the Internet. Exposure is based on general principles but tailored to suit the needs of each patient. Outcomes include patient-reported credibility and expectancy, adherence to the treatment protocol, client satisfaction, and negative events. Within-group effects will also be quantified and discussed in relation to the existing literature.

Detailed description

Background: A substantial portion of patients in routine care suffer from a recurrent preoccupation with physical symptoms, which often leads to substantial suffering and impairment. Exposure-based treatment - where the patient systematically seeks out that which gives rise to unwanted sensations, cognitions, or behavior - has been found to lead to beneficial effects in several types of symptom preoccupation. Yet, this form of treatment is rarely offered in routine care. This may be partially because existing treatment protocols have been developed for specific symptom clusters (e.g., functional somatic syndromes such as irritable bowel syndrome and fibromyalgia) or specific unwanted responses to symptoms (e.g., the fear of having a severe illness), and that many clinics do not have the resources to offer all these specialized protocols in parallel. An alternative approach could be to base exposure treatment on a more general protocol that may be tailored to suit a larger variety of patient groups who suffer from a recurrent preoccupation with physical symptoms. However, it is yet unclear if the use of such a general treatment protocol for symptom preoccupation would be feasible, for example in terms of patient-reported credibility, adherence, identification with the rationale, and general client satisfaction. Aim: To investigate the feasibility of delivering exposure-based treatment using a general protocol for clinically significant symptom preoccupation, without selecting patients based on any specific symptom cluster (such as a functional somatic syndrome) or specific unwanted response to physical symptoms (such as a frequent fear of illness). Design: This is a prospective single-group feasibility study based at Karolinska Institutet, Stockholm, Sweden, where 40 adults with somatic symptom disorder according to the Diagnostic and statistical manual of mental disorders 5 (DSM-5) are enrolled in 8 weeks of therapist-guided exposure-based treatment that is delivered via the Internet. Various aspects of feasibility are assessed; most notably: patient-reported credibility and expectancy, adherence to the treatment protocol, client satisfaction, and negative events. Within-group effects are also quantified.

Interventions

BEHAVIORALExposure

Systematic confrontation with stimuli associated with symptom-related distress, to achieve therapeutic changes in cognitions or behavior

Study design

Allocation

Intervention model

SINGLE_GROUP

Primary purpose

TREATMENT

Masking

NONE

Masking description

Psychological intervention, patient-reported outcomes

Intervention model description

Prospective single-group cohort study

Eligibility

Sex/Gender

ALL

Age

18 Years to No maximum

Healthy volunteers

Inclusion criteria

* DSM-5 somatic symptom disorder * Interest in 8-week intensive psychological treatment to reduce distress and the impact of physical symptoms * At least 18 years old * Living in Sweden * Fluent in Swedish * Complete pre-treatment assessment

Exclusion criteria

* Preoccupation with physical symptoms better explained by another psychiatric condition such as illness anxiety disorder, panic disorder, or obsessive-compulsive disorder * Severe psychiatric condition, such as bipolar disorder, suicidal ideation, or psychosis * Medical risks associated with participating in exposure-based treatment, or somatic condition - or treatment for somatic condition - that is an obstacle to participating in exposure-based treatment * Non-stable continuous pharmacotherapy (dosage changed during the past 4 weeks) and the drug is likely to affect outcome measures (primarily: antidepressants, anticonvulsants, benzodiazepines, nonbenzodiazepines, opioids) * Alcohol or substance use that is a clear obstacle to therapy * Planned absence for more than 1 week of the treatment period

Design outcomes

Primary

Measure	Time frame	Description
Feasibility 1: Distribution of Physical Symptoms	Pre-treatment assessment (within 2 weeks before treatment)	According to the Patient Health Questionnaire-15 (PHQ-15, theoretical range: 0-30, higher score indicates more distressing physical symptoms)
Feasibility 2: Credibility/Expectancy Based on the Credibility/Expectancy Scale	Week 3 of treatment	Theoretical range: 0-50, higher score indicates higher credibility/expectancy
Feasibility 3: Adherence to the Protocol #1: Percentage Completed Modules in the Sample as a Whole	Adherence data collected over the entire course of the treatment, up to 8 weeks.	Preregistered target: at least 60% completed modules in the sample as a whole. In this study, all participants were enrolled in the same type of treatment and were thus offered to work with the same treatment modules. This outcome was the proportion of modules completed in total by all participants, out of the total modules available to all participants.
Feasibility 4: Patient-reported Adequacy of Rationale as Assessed Using a Questionnaire Developed Specifically for This Purpose (Theoretical Range: 0-10)	Post-treatment assessment (immediately after treatment, completed within 45 days)	From 0 (not at all relevant) to 10 (extremely relevant). Was originally intended to be administered at week 3, but was administered post-treatment due to an administrative error
Feasibility 5: Adequacy of the Measurement Strategy	Post-treatment assessment (immediately after treatment, completed within 45 days)	Preregistered target: less than 30% missing data at post-treatment, and at least 75% finding the measurement strategy acceptable (less than 7 on a scale from 0 \[Not at all stressful/bothering\] to 10 \[Extremely stressful/bothering\])
Feasibility 6: Satisfaction With Treatment as Indicated by a Mean Client Satisfaction Questionnaire (CSQ-8) Score of at Least 22	Post-treatment assessment (immediately after treatment, completed within 45 days)	Theoretical range: 8-32, higher score indicates higher satisfaction. This sum score is based on 8 items, each scored 1-4.
Feasibility 7a: Adverse Events Measured Using Free-text Items #1: Total Number of Reported Events	Post-treatment assessment (immediately after treatment, completed within 45 days)	The respondent was instructed to describe up to three adverse events.
Feasibility 7b: Adverse Events Measured Using the 20-item Negative Effects Questionnaire (NEQ-20)	Post-treatment assessment (immediately after treatment, completed within 45 days)	Theoretical range: 0-80, higher score indicates more severe adverse events
Feasibility 3: Adherence to the Protocol #2: Percentage of Participants Completing at Least 2 Exposure Exercises	Adherence data collected over the entire course of the treatment, up to 8 weeks.	Preregistered target: at least 50% of participants completing at least 2 exposure exercises
Feasibility 7a: Adverse Events Measured Using Free-text Items #2: Number of Participants Who Reported at Least One Adverse Event	Post-treatment assessment (immediately after treatment, completed within 45 days)	The respondent was instructed to describe up to three adverse events.

Secondary

Measure	Time frame	Description
Patient Health Questionnaire-15 (PHQ-15)	Screening, pre-treatment assessment (within 2 weeks before treatment), weekly during treatment, Post-treatment assessment (immediately after treatment, completed within 45 days), 3 months after treatment	Change pre-post, as derived from linear mixed effects regression models fitted by maximum likelihood estimation using data from all 33 participants, and fitted on all 11 measurement points over the treatment phase (from pre-treatment to post-treatment). Theoretical range: 0-30, higher score indicates more distressing physical symptoms
Working Alliance Inventory (WAI)	Week 3 of treatment	Theoretical range: 6-42, higher score indicates better relationship with the therapist
Somatic Symptom Disorder-B Criteria Scale (SSD-12)	Screening, pre-treatment assessment (within 2 weeks before treatment), weekly during treatment, Post-treatment assessment (immediately after treatment, completed within 45 days), 3 months after treatment	Change pre-post, as derived from linear mixed effects regression models fitted by maximum likelihood estimation using data from all 33 participants, and fitted on all 11 measurement points over the treatment phase (from pre-treatment to post-treatment). Theoretical range: 0-48, higher score indicates higher degree of preoccupation with symptoms
Symptom Preoccupation Scale (Preliminary Scale)	Screening, pre-treatment assessment (within 2 weeks before treatment), weekly during treatment, Post-treatment assessment (immediately after treatment, completed within 45 days), 3 months after treatment	Under development, higher score indicates higher degree of preoccupation with symptoms. This is to be regarded as an item pool that will be further analyzed in 2024-2025, and in conjunction with data from other clinical trials. As of September 2023, it is therefore not yet possible to provide a theoretical range for this scale, and it is also not possible to provide outcomes.
14-item Health Anxiety Inventory (HAI-14)	Screening, pre-treatment assessment (within 2 weeks before treatment), Post-treatment assessment (immediately after treatment, completed within 45 days), 3 months after treatment	Change pre-post, as derived from linear mixed effects regression models fitted by maximum likelihood estimation using data from all 33 participants, and fitted on all 11 measurement points over the treatment phase (from pre-treatment to post-treatment). Theoretical range: 0-42, higher score indicates more health anxiety
Anxiety Sensitivity Index (ASI)	Screening, pre-treatment assessment (within 2 weeks before treatment), post-treatment assessment Post-treatment assessment (immediately after treatment, completed within 45 days), 3 months after treatment	Change pre-post, as derived from linear mixed effects regression models fitted by maximum likelihood estimation using data from all 33 participants, and fitted on all 11 measurement points over the treatment phase (from pre-treatment to post-treatment). Theoretical range: 0-64, higher score indicates more anxiety sensitivity
GAD-7	Pre-treatment assessment (within 2 weeks before treatment), post-treatment assessment Post-treatment assessment (immediately after treatment, completed within 45 days), 3 months after treatment	Change pre-post, as derived from linear mixed effects regression models fitted by maximum likelihood estimation using data from all 33 participants, and fitted on all 11 measurement points over the treatment phase (from pre-treatment to post-treatment). Theoretical range: 0-21, higher score indicates more general anxiety
Patient Health Questionnaire (PHQ-9)	Screening, pre-treatment assessment (within 2 weeks before treatment), weekly during treatments (suicidality), post-treatment assesment (immediately after treatment, completed within 45 days), 3 months after treatment	Change pre-post, as derived from linear mixed effects regression models fitted by maximum likelihood estimation using data from all 33 participants, and fitted on all 11 measurement points over the treatment phase (from pre-treatment to post-treatment). Theoretical range: 0-27, higher score indicates more symptoms of depression
12-item WHO Disability Assessment Schedule 2.0 (WHODAS 2.0)	Screening, pre-treatment assessment (within 2 weeks before treatment), post-treatment assessment (immediately after treatment, completed within 45 days), 3 months after treatment	Change pre-post, as derived from linear mixed effects regression models fitted by maximum likelihood estimation using data from all 33 participants, and fitted on all 11 measurement points over the treatment phase (from pre-treatment to post-treatment). Theoretical range: 0-100, higher score indicates more disability
Alcohol Use Disorders Identification Test (AUDIT)	Screening only	Theoretical range: 0-40, higher score indicates more problematic alcohol use
Drug Use Disorders Identification Test (DUDIT)	Screening only	Theoretical range: 0-44, higher score indicates more problematic substance use

Countries

Sweden

Participant flow

Recruitment details

We originally aimed to recruit 40 participants for 80% power in two-sided tests of moderate effects (d=0.5) on efficacy outcomes measured at two time points, given a 5% alpha and 15% missing data at post-treatment. In light of the high data retention, prior to the data analysis, we ended the recruitment with 33 participants included in November 2020.

Pre-assignment details

All participants were enrolled in treatment.

Participants by arm

Arm	Count
Internet-delivered Exposure-based Treatment Eight weeks of therapist-guided exposure-based treatment delivered via the Internet. Exposure: Systematic confrontation with stimuli associated with symptom-related distress, to achieve therapeutic changes in cognitions or behavior	33
Total	33

Baseline characteristics

Characteristic	Internet-delivered Exposure-based Treatment	—
Age, Continuous	46 years STANDARD_DEVIATION 14	—
Employment Retired	4 Participants	—
Employment Student	1 Participants	—
Employment Working full-time	21 Participants	—
Employment Working part-time (<90%)	7 Participants	—
Race and Ethnicity Not Collected	—	— Participants
Region of Enrollment Sweden	33 participants	—
Sex: Female, Male Female	22 Participants	—
Sex: Female, Male Male	11 Participants	—
University education	27 Participants	—

Adverse events

Event type	EG000 affected / at risk
deaths Total, all-cause mortality	0 / 33
other Total, other adverse events	5 / 32
serious Total, serious adverse events	0 / 33

Outcome results

Primary

Feasibility 1: Distribution of Physical Symptoms

According to the Patient Health Questionnaire-15 (PHQ-15, theoretical range: 0-30, higher score indicates more distressing physical symptoms)

Time frame: Pre-treatment assessment (within 2 weeks before treatment)

Arm	Measure	Value (MEAN)
Internet-delivered Exposure-based Treatment	Feasibility 1: Distribution of Physical Symptoms	11.8 score on a scale

Primary

Feasibility 2: Credibility/Expectancy Based on the Credibility/Expectancy Scale

Theoretical range: 0-50, higher score indicates higher credibility/expectancy

Time frame: Week 3 of treatment

Population: All participants completed the week 3 assessment.

Arm	Measure	Value (MEAN)	Dispersion
Internet-delivered Exposure-based Treatment	Feasibility 2: Credibility/Expectancy Based on the Credibility/Expectancy Scale	34.5 score on a scale	Standard Deviation 7

Primary

Feasibility 3: Adherence to the Protocol #1: Percentage Completed Modules in the Sample as a Whole

Preregistered target: at least 60% completed modules in the sample as a whole. In this study, all participants were enrolled in the same type of treatment and were thus offered to work with the same treatment modules. This outcome was the proportion of modules completed in total by all participants, out of the total modules available to all participants.

Time frame: Adherence data collected over the entire course of the treatment, up to 8 weeks.

Population: In this study, all 33 participants were enrolled in the same type of treatment and were thus offered to work with the same five treatment modules.

Arm	Measure	Value (COUNT_OF_UNITS)
Internet-delivered Exposure-based Treatment	Feasibility 3: Adherence to the Protocol #1: Percentage Completed Modules in the Sample as a Whole	150 Modules

Primary

Feasibility 3: Adherence to the Protocol #2: Percentage of Participants Completing at Least 2 Exposure Exercises

Preregistered target: at least 50% of participants completing at least 2 exposure exercises

Time frame: Adherence data collected over the entire course of the treatment, up to 8 weeks.

Arm	Measure	Value (COUNT_OF_PARTICIPANTS)
Internet-delivered Exposure-based Treatment	Feasibility 3: Adherence to the Protocol #2: Percentage of Participants Completing at Least 2 Exposure Exercises	32 Participants

Primary

Feasibility 4: Patient-reported Adequacy of Rationale as Assessed Using a Questionnaire Developed Specifically for This Purpose (Theoretical Range: 0-10)

From 0 (not at all relevant) to 10 (extremely relevant). Was originally intended to be administered at week 3, but was administered post-treatment due to an administrative error