Figure 2.

Number of outpatient prescriptions dispensed in the United States for the calendar year 2013 for top 30 drugs with high pharmacogenetic risk plotted by drug and diplotype risk category. The dark grey portion of each bar represents prescriptions potentially prescribed to blacks or whites with a high-risk diplotype for the applicable gene(s); the light grey portion represents those prescribed to those without a high-risk diplotype. Total number of prescriptions for each drug was collected from the IMS Health (IMS) National Prescription Audit proprietary prescription database (32). This database contains all retail prescriptions filled from a representative sample of 35,000 (73% of the approximately 50,000) U.S.-based retail pharmacies. IMS then proportionately extrapolates their data on the basis of populations served by the included pharmacies to provide weekly estimates of all prescriptions filled in the United States for these drugs. The National Prescription Audit database does not track prescriptions filled by in-hospital pharmacies.

The number of prescriptions potentially prescribed to black or white patients with a high-risk diplotype per drug was calculated as follows: (total number of prescriptions for a drug) * (percent of Americans with Caucasian ancestry (74.8%)) * (percent of high-risk diplotypes in whites for each corresponding gene as shown in Figure 1) + (total number of prescriptions for a drug) * (percent of Americans with African American ancestry (12.6%)) * (percent of high-risk diplotypes in blacks for each corresponding gene as shown in Figure 1), where the percent of Caucasians and African Americans was derived from the 2010 U.S. census (http://www.census.gov/2010census/). For warfarin, only whites with a high-risk diplotype were used in the calculation. If the drug is affected by two genes, the presence of a high-risk diplotype for either gene was considered as the presence of a high-risk diplotype for that drug.