A Hybrid Type 1 Trial Evaluating the Feasibility, Acceptability, Preliminary Effectiveness of Brief Cognitive-behavioral Therapy for Health Anxiety Delivered by Medical Assistants in Primary Care

Seventy-two health anxious patients with a diagnosis of Illness Anxiety Disorder or Somatic Symptom Disorder will be randomly assigned to either receive brief cognitive-behavioral therapy (CBT) administered by a medical assistant in the primary care practice where the patient receives their primary care services (intervention condition) or receive a referral to a mental health provider within the outpatient psychiatry clinic or another community provider of their choice (usual care condition). Randomization will be determined by a random number generation program at the point of enrollment. The randomization scheme will be stratified by primary care site to reduce site effects. The primary care sites from which patients will be recruited include the General Internal Medicine clinic at Dartmouth-Hitchcock Medical Center, Dartmouth-Hitchcock Heater Road clinic, and Dartmouth-Hitchcock Manchester. Recruitment will be evenly distributed across sites. The investigators will over-sample racial and ethnic minority patients at Dartmouth-Hitchcock Manchester due to the higher proportion of minority patients receiving services at that location.

The brief CBT intervention is a 4-session psychotherapy comprised of techniques guided by cognitive-behavioral theory and specifically derived from previously published materials. Each technique has support from prior randomized controlled trials demonstrating their efficacy for reducing symptoms of health anxiety and expert consensus. The techniques employed include motivational interviewing, psychoeducation, cognitive restructuring, and situational and interoceptive exposure. Each session of brief CBT is 45-minutes in duration and is delivered by a medical assistant who is principally located at the patient's primary care practice. All sessions are based on a manual developed by the Principal Investigator that includes essential elements to deliver at each session, scripts to guide delivery of the intervention, and homework assignments for the patient to complete between sessions and after completion of the final session. The Principal Investigator provides clinical supervision of the intervention over the course of the study.

The referral process employed in the usual care condition consists of an electronic referral made by the patient's primary care provider to a mental health provider within the Dartmouth-Hitchcock Health system, or a community provider outside of the system identified by the patient in consultation with the primary care provider. The nature of the intervention provided by the mental health provider is not prescribed or guided by the study protocol.

Examination of distributions of all variables using descriptive analyses will precede inferential statistical analysis. Transformations or recoding will be applied to normalize continuous data when necessary. The success of random assignment will be evaluated by comparing the two study groups on baseline characteristics using chi-square tests for categorical variables and t-tests for continuous covariates. If baseline variables are significantly different between groups and are significantly associated with the outcomes (e.g., medical comorbidity), the investigators will include them as covariates in the analytic models.

The primary outcome of change in health anxiety will be tested using a model that accommodates attrition and is appropriate for correlated data due to clustering (by 3 sites and 6 medical assistants) and repeated measures (baseline, 4 and 12 weeks) on the outcomes. Because there are only three assessment points, time will be treated as discrete and fitted to a covariance pattern model to compare average change between groups over time. Group (CBT vs usual care), time (baseline, 4 and 12 weeks), and the group by time interaction will be specified for the model. The treatment effect of intervention relative to control will be evaluated by testing significance of the group by time interaction term. An unstructured variance-covariance structure will be specified to account for the correlated nature of the data due to repeated measures.