Halifax Somatic Symptoms Disorder Trial

The purpose of our study Given the significant illness burden associated to somatic symptom and related disorders, and given the marked reduction in ED visits and severity of symptoms following this form of short-term treatment, there is an urgent need to directly examine those patients who do not attend initial consultation or fail to complete treatment. This population is complex and is considered at high risk. Currently, insufficient information is known about the specific baseline characteristics, and the short- and long-term outcomes for these two sub-samples of patients not initiating or not completing treatment.

Objectives

• First, we will examine the outcomes of patients receiving Medical Care As Usual (MCAU) followed by an 8-week wait-list for ISTDP versus MCAU plus ISTDP without wait in order to establish the efficacy of this treatment for somatic symptom disorders.
• Second, we will identify specific patient variables that predict outcomes in order to identify the characteristics of patients with less optimal outcomes and treatment failures.
• Third, we will conduct a preliminary examination of processes underlying symptom change in ISTDP.

Specific goal Through this project, therefore, we will generate new knowledge directly translatable to the goal of improving outcomes for a greater percentage of referred patients. This population is complex and is considered at high risk. There is a pressing need to reach out to a greater number of patients with SSRD, in order to alleviate suffering and reduce the costs associated to repeated health care use.

METHOD

Design Using a randomized control trial design this study will examine the efficacy of ISTDP for patients with Somatic Symptom and Related Disorders (SSRD). Participants are randomly allocated to either MCAU plus ISTDP or MCAU. The primary outcome measure is somatic symptoms severity score (SOMS-7 SS)5 at T1 (8 weeks). After 8-weeks in the MCAU condition participants will then crossover to ISTDP if necessary.

Setting and study sample Eligible participants will be new referrals to the Capital District Health Authority Medically Unexplained Symptoms clinic by an emergency department physician for assessment and possible treatment for unexplained somatic symptoms. Referrals will be accepted from physicians at two local emergency wards (Halifax and Dartmouth). Participants will be adult outpatients, aged 18-65 years, meeting the study inclusion and exclusion criteria.

Psychiatric Diagnoses Psychiatric diagnoses will be established using the SCID 5-RV13 administered by a trained research assistant. The assessment will include administration of the SCID 5-RV overview to evaluate medical, psychiatric and personal history, and also information on demographic factors (age, gender, marital status, education, professional occupation).

Co-occurring therapies At each time point participant will be asked to self-report their use of concurrent treatment, intervention or other management strategies e.g., pain medication, psychiatric medication (antidepressant medication), consultation with family physician, specialist clinic appointments.

Change processes measures Trained researchers will review videotaped recordings of ISTDP and rate therapist and patient behavior including the following scales: (a) Achievement of Therapeutic Objective Scale (ATOS), a measure of the degree to which patients achieve in-session treatment objectives (e.g., Affective Experiencing); (b) Comparative Psychotherapy Process Checklist (CPPS), includes two scales for rating how characteristic the therapists' interventions are of Psychodynamic-Interpersonal versus Cognitive-Behavioural treatments; (c) ISTDP Process Scale, a measure for assessing the degree of mobilization of unconscious processes, consistent with ISTDP theory.

Statistical Power The required sample size for this pilot study was set at 40 in order to provide sufficient data to conduct preliminary analyses of the stated study objectives.

Analysis The primary analysis population is the intention-to-treat (ITT) sample. Secondary analysis will be calculated in an observed-cases sample, which will consist of all patients where complete observed data is available. Sub-analyses will examine three definitions of ISTDP treatment: Completed when 20 sessions have been delivered or the termination of treatment occurs by mutual consensus based on symptom remission and/or agreement that an adequate treatment dose has been delivered; Partial Treatment when 2 or more sessions are attended; Trial only attended. For these analyses, missing data will be replaced through a multiple imputation approach where possible.

Initially group differences will be examined using analyses of covariance (ANCOVA) to assess efficacy (SOMS-SSI) at 8-week post allocation. Clinically significant change in somatic symptoms will be examined by first calculating the Reliable Change Index (RCI) to assess psychometrically reliable change at the patient level. Next, the post treatment test scores are examined to determine whether they fall below the clinical cut-off, within 2 SD of the normative mean. Patients who meet both criteria are considered to have achieved clinically significant change. Finally, overall effectiveness of ISTDP will be examined using the whole treated sample at two time points; the final treatment session and 6-month post treatment. Separate analyses will include number of treatment sessions as a covariate of outcome.

Process analyses A series of regression analyses will be conducted to examine if changes in putative moderator and mediator variables predict between group (ISTDP v. MCAU) treatment efficacy (SOMS-SSI). Hypothesized processes of change in somatic symptom severity across ISTDP sessions will be examined using parallel process latent growth curve models.