Pharmacogenomic testing in a tertiary care outpatient psychosomatic medicine practice

Pharmacogenomic testing (PGT) has applicability in psychosomatic medicine (PM) practice where medical comorbidity and polypharmacy present particularly difficult challenges of drug-drug and drug-disease interactions. No guidelines currently exist for cost-effective use of PGT in PM practice.

The authors tested the hypothesis that naturalistically observed PGT ordering patterns and clinical data on test utility derived from a PM practice where PGT is readily available may inform the development of clinical guidelines for cost-effective use of PGT.

Two sets of data were collected from an outpatient PM practice staffed by seven PM-certified psychiatrists. Psychiatrists were surveyed regarding their indications for ordering PGT. Medical records of patients seen in the PM practice during 2008 were reviewed. Patients who had PGT were compared with two sets of case controls who were not tested, one matched by demographics, the other by ordering psychiatrist. Psychiatrists' ordering indications were compared with clinical data derived from the case-control analyses.

Psychiatrists listed treatment-resistance as the most common reason for PGT, ahead of intolerance to previous medications. Tested patients differed from controls on measures of both clinical severity and treatment-resistance, including higher self-reported anxiety and depression levels, greater likelihood of family history of mood or anxiety disorders, and larger numbers of prior antidepressant, mood stabilizer, and antipsychotic medication trials.

Ordering guidelines that emphasize markers of clinical severity and early indicators of treatment-resistance may provide a useful rationale for PGT in outpatient PM practice. Prospective investigations of this proposition are warranted.