Exposure Therapy for Reactivity to Symptoms

Persistent physical symptoms refers to somatic complaints that persist for months or more and give rise to significant distress, regardless of etiology. Common complaints such as gastrointestinal symptoms, fatigue, and pain have been estimated to account for up to half of primary care consultations, can be difficult to classify, and often defy straightforward medical explanation. In light of substantial personal and socioeconomic repercussions, effective clinical interventions are needed. The investigators recently completed a randomized controlled trial in primary care (SOMEX1) where individuals with persistent physical symptoms were randomized to 10 weeks of exposure therapy or healthy lifestyle promotion. Based on that trial, exposure therapy appears to have a small average advantage over healthy lifestyle promotion in mean effect on symptom preoccupation, i.e., the patient's tendency to respond strongly to, and engage in behaviors contingent on, somatic symptoms, and also on patient satisfaction. In line with a priori hypotheses, this added effect on symptom preoccupation was larger, and an advantage in the effect on somatic symptom burden was also seen, when patients reported a very high general somatic symptom burden or symptom preoccupation before treatment. For example, a patient with a PHQ-15 score of 10 could expect a near-zero added effect of exposure therapy on somatic symptom burden (d = 0.08) and a small added effect on symptom preoccupation (d = 0.31), whereas a patient with a PHQ-15 score of 15 could expect a small to moderate added effect on somatic symptom burden (d = 0.37) and a moderate added effect on symptom preoccupation (d = 0.62). An unexpected finding, however, was that in exposure therapy, the correlation between the participant's number of exposure exercises and reduction in symptom preoccupation was weak (rs=0.21-0.26). This highlights the fact that it is yet unclear to what degree the two main components of exposure therapy - exposure and response prevention - contribute to the treatment effects. It is also unclear what patient- and contextual factors moderate the added effect of exposure.

The aim of the present project is to focus on the aforementioned subgroup of patients who benefit specifically from exposure therapy, and to determine to what degree this is driven by the addition of exposure to response prevention. This will be evaluated on the basis of a randomized controlled trial (N=360; SOMEX2) where participants with a high general somatic symptom burden or high symptom preoccupation are enrolled in response prevention (n=180), or exposure and response prevention (n=180). Primary outcome will be between-group differences in the reduction in symptom preoccupation as measured week-by-week using the somatic symptom disorder B-criteria scale (SSD-12). The participants will be blinded to the study design and the hypotheses of the investigators. Results from this project will be informative for exposure-based and various multicomponent behavioral treatments for primary care patients with persistent physical symptoms worldwide.

• Primary research question:

Is there a significant average advantage, d≥0.30, of exposure and response prevention, as compared to response prevention only, with regard to the reduction in symptom preoccupation (SSD-12) up to the post-treatment assessment? Hypothesis: Yes.

• Key secondary research questions:

Is the average advantage of adding exposure to response prevention moderated by the frequency of opportunities for response prevention as measured at baseline? Hypothesis: Yes, more opportunities are predictive of a smaller added effect of exposure exercises.

Is the average advantage of adding exposure to response prevention moderated by the temporality of unwanted outcomes as measured at baseline? Hypothesis: Yes, more distal unwanted outcomes are predictive of a larger added effect of exposure exercises.

Is the average advantage of adding exposure to response prevention moderated by anxiety sensitivity - i.e., reactivity to physiological arousal - at baseline? Hypothesis: Yes, a higher anxiety sensitivity is predictive of a larger added effect of exposure exercises.

Which additional variables act as moderators and mediators of added effects (below)?

Are there average advantages of adding exposure (superiority, ds≥0.30) with regard to general somatic symptom burden, core depressive symptoms, or functional impairment? Hypothesis: No.

What is the cost-effectiveness of exposure and response prevention versus response prevention? Exploratory analyses.

Inclusion criteria

• Bothered by at least one somatic symptom for at least 4 months.
• High symptom burden, defined as a PHQ-15≥15 or SSD-12≥25.
• Adult (≥18 years old).
• Living in Stockholm County (catchment area of the clinic).
• Sufficient technical knowledge with web-enabled device and fluent in Swedish.
• Complete pre-treatment assessment.

Exclusion criteria

• A maximum of half the sample (180 participants) will be included with health anxiety, i.e., a fear of or preoccupation with serious illness, as their principal clinical problem.
• Clinical picture dominated by non-somatoform psychiatric disorder such as depression, panic disorder, or primary insomnia. Comorbidities are allowed.
• Severe psychiatric condition (e.g., ongoing manic episode, psychotic disorder, severe depression) or markers for suicidality beyond sporadic ideation.
• Clear medical risk in taking part in exposure-based treatment (e.g., pregnancy), or somatic condition, or treatment for somatic condition, makes treatment unfeasible.
• Continuous psychotropic medication (antidepressants, anticonvulsants, mood-stabilizers, antipsychotics) is present and has either not been stable for at least 4 weeks, or is not expected to remain stable.
• Other psychotherapy or planned absence >1 week during intended main phase.