Hybrid Trial of Brief Cognitive-Behavioral Therapy for Health Anxiety 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.

The cluster size at site and provider levels are too small to be treated as random effects;
therefore, the analysis will take clustering effects due to site and provider into account
using small-sample robust estimate correction options implemented in the Statistical Analysis
Software (SAS) generalized linear mixed models procedure (PROC GLIMMIX) procedure. GLIMMIX
facilitates conducting mixed-effects and generalized estimating equation (GEE) modeling in
the same procedure simultaneously.

The sample size was determined by a combination of recruitment feasibility, study therapist
(medical assistant) availability, and power analysis. Given two groups, 3-assessment points,
and sample size of 72 (36 per arm) with 15% attrition at 12 months (N = 58), and assuming
cross-time correlation of 0.60, alpha of 0.05, and two-tailed tests, the study achieves 80%
power to detect a minimum effect size of 0.69, between medium (0.50) and large (0.80) in
Cohen's d-metric. If the analysis takes clustering effects due to site and providers into
account by adjusting the sample size with an intraclass correlation (ICC) of 0.01, the study
achieves 80% power to detect an effect size of 0.72. Statisticians recommend ICC between 0.01
and 0.02 in clinical studies with clustering; the investigators used ICC = 0.01 for this
power calculation. A larger sample size is needed to detect effect sizes smaller than 0.69
and 0.72; however, sample size for pilot study should be based on pragmatics of recruitment
and the necessities for examining feasibility, and not for purpose of inferential statistical
tests.

The investigators will assess acceptability of the intervention and strategy using scores on
a self-report measure of treatment acceptability using mean scores above a predetermined cut
score denoting moderate acceptability across all participants. The investigators assess study
therapist fidelity to the treatment by compiling standardized fidelity ratings for each
session, nested within each provider, and converted to a percentage fidelity score.

Finally, the investigators will assess acceptability qualitatively using qualitative
interviews with medical assistants, primary care providers, and clinic administrators.
Interview data will be transcribed and entered verbatim into a qualitative data management
software package for content analysis. Content analysis consists of reviewing the responses
of interviewees to identify responses that are coded to correspond to Consolidated Framework
for Implementation Research constructs. Coding will be conducted by two independent coders
(the Principal Investigator and a research assistant) and overseen by a medical
anthropologist.

Inclusion Criteria:

- Age of 18 years to 85

- Have a primary care provider at Dartmouth-Hitchcock Medical Center—General Internal
Medicine, Dartmouth-Hitchcock Heater Road Clinic, or Dartmouth-Hitchcock Manchester

- Primary care visit frequency of two standard deviations above the mean for patients in
the individual's age by gender cohort

- Elevated self-reported health anxiety (≥2 on Whiteley Index-7)

- Diagnosis of illness anxiety disorder or somatic symptom disorder determined by Health
Anxiety Interview

Exclusion Criteria:

- Non-English speaking

- Chronic medical illness necessitating an increased visit frequency confirmed through
consultation with the patient's primary care provider

- Active suicidal ideation

- Unmanaged psychosis or unmanaged bipolar disorder