Pharmacogenomic Testing in Major Depressive Disorder

This is a two-arm double-blind prospective randomized controlled trial (RCT) to evaluate clinical impact of pharmacogenomic testing on the treatment of major depressive disorder. Participants will be randomly assigned to two groups: pharmacogenomic-guided therapy group (guided group) and treatment as usual group (TAU group). The primary hypothesis is the pharmacogenomic-guided treatment group will demonstrate significantly higher percent improvement in depression score compared to treatment-as-usual group.

To a large extent, variability in antidepressant efficacy can be explained by genetic variations that affect medication-metabolizing enzymes, drug transporters, and medication targets. Recent reviews demonstrated significant potential of pharmacogenomic testing in improving treatment of major depressive disorder. One of the major barriers towards successful implementation of pharmacogenomic testing for patients with major depressive disorder is lack of systematic evaluation of impact of this approach in routine clinical care settings. The major goal of this study is to systematically evaluate impact of comprehensive pharmacogenomic testing on the treatment of major depressive disorder in ambulatory setting.

In this group, results of pharmacogenomic testing will be provided to the treating physician within 2-5 working days. Thus, the patient's treatment provider will be able begin antidepressant adjustments based on pharmacogenomic testing report within a week of the baseline visit.

For patients randomized to this group, medication treatment decisions by the treating clinicians will be made without the availability of the pharmacogenomic report; however, the test results will be provided after the study completion to the patient treating physician.

Pharmacogenomic testing is delivered to treating providers of patients with major depressive disorder

The patient is rated by a clinician among 17 dimensions with a score on a 3 or 5 point scale. A score of 0-7 is considered to be normal. Scores of 20 or higher indicate moderate, severe, or very severe depression, and are usually required for entry into a clinical trial.

The Quick Inventory of Depressive Symptomatology is a short screening tool based on the larger Inventory of Depressive Symptomatology (IDS). Each item is scored on a scale from 0 to 3 points. Total scores range from 0 (no depression) to 27 (severe depression).

The PHQ-9 is the depression module, which scores each of the nine DSM-IV criteria as "0" (not at all) to "3" (nearly every day). Higher PHQ-9 scores are associated with decreased functional status and increased symptom-related difficulties, sick days and healthcare utilization.

Inclusion Criteria: Clinical diagnosis of major depressive disorder (MDD) Prescription of index antidepressant medications Minimum score of 14 on the 17-item Hamilton Rating Scale for Depression (HAMD-17) Exclusion Criteria: Diagnosis of bipolar disorder (any type), schizophrenia, or schizoaffective disorders Active diagnosis of substance abuse or dependence Current suicidal ideation Previous suicidal attempts A person has already had pharmacogenetic testing done.