Incidence of Exposure of Patients in the United States to Multiple Drugs for Which Pharmacogenomic Guidelines Are Available

<div><p>Pre-emptive pharmacogenomic (PGx) testing of a panel of genes may be easier to implement and more cost-effective than reactive pharmacogenomic testing if a sufficient number of medications are covered by a single test and future medication exposure can be anticipated. We analysed the incidence of exposure of individual patients in the United States to multiple drugs for which pharmacogenomic guidelines are available (PGx drugs) within a selected four-year period (2009–2012) in order to identify and quantify the incidence of pharmacotherapy in a nation-wide patient population that could be impacted by pre-emptive PGx testing based on currently available clinical guidelines. In total, 73 024 095 patient records from private insurance, Medicare Supplemental and Medicaid were included. Patients enrolled in Medicare Supplemental age > = 65 or Medicaid age 40–64 had the highest incidence of PGx drug use, with approximately half of the patients receiving at least one PGx drug during the 4 year period and one fourth to one third of patients receiving two or more PGx drugs. These data suggest that exposure to multiple PGx drugs is common and that it may be beneficial to implement wide-scale pre-emptive genomic testing. Future work should therefore concentrate on investigating the cost-effectiveness of multiplexed pre-emptive testing strategies.</p></div

Classification of potential clinical effects observed in patients with risk phenotypes, based on DPWG guidelines.

<p>Classification of potential clinical effects observed in patients with risk phenotypes, based on DPWG guidelines.</p

Number of expected drug-phenotype co-occurrences of highest priority according to CPIC guidelines (CPIC level A) or high clinical significance according to DPWG guidelines (DPWG clinical significance classes C–F) within the observed four-year time window.

<p>PGx drugs included in all estimations: amitriptyline, azathioprine, clomipramine, clopidogrel, doxepin, glimepiride, haloperidol, imipramine, mercaptopurine, metoprolol, nortriptyline, paroxetine, propafenone, risperidone sertraline, tamoxifen, thioguanine, tramadol, venlafaxine. Estimations which additionally included codeine are shown for comparison. The rationale for including / excluding drug substances is described in the Methods section (‘Drug substances included in the estimation’).</p

Distribution of incident use within four-year time window among therapeutic areas.

<p>Distribution of incident use within four-year time window among therapeutic areas.</p

Incidence of exposure to drugs for which pre-emptive pharmacogenomic testing is available.

<p>Incidence of exposure to drugs for which pre-emptive pharmacogenomic testing is available.</p

Examples of health systems that have launched pharmacogenomics initiatives.

<p>Examples of health systems that have launched pharmacogenomics initiatives.</p

Overview of drugs for which CPIC or DPWG guidelines were available at the time of our analysis (mid-2014).

<p>Drugs and substances that we assigned to the ‘core list’ are listed separately. Only ‘core list’ substances were used for generating prescription statistics. Drug substances that were included in the estimation of the number of high-risk drug-phenotype co-occurrences are printed in bold.</p