With the expansion of drugs available for pharmacogenetic (PGx) testing, primary care physicians (PCPs) will likely become major users of these tests. Pharmacogenetics uses genetic tests to determine the proper and optimal pharmaceutical therapy for an individual patient with the goal of reducing adverse reactions and improving drug efficacy. Because implementation of PGx testing has been slow, this national survey of a sample of PCPs was undertaken to assess their training, familiarity with, and attitudes toward PGx testing and to identify barriers to test use. Primary care physicians were asked about their willingness and readiness to use PGx testing, desirable test properties, and relevant factors for using such tests.
Survey questions were based on a literature review and focus groups of health professionals. After a pretest survey was completed by a panel of PCPs, the final survey had 6 major parts with 101 questions. The survey sample was obtained from the AMA Physician Masterfile through Direct Medical Data. Inclusion criteria were board certification in either family medicine or internal medicine but not in a subspecialty, licensed to practice in their state of residence, and graduated between 1970 and 2003. A total of 4000 names were randomly selected from 47,348 internists and 47,179 family medicine practitioners. Data were collected from a mailed survey invitation and questionnaire. Of 3045 confirmed names and addresses, 597 completed the survey, 3 were not eligible, and 2445 did not respond, for a cooperation rate of 20% (597/3042).
When PCPs were asked if they felt well informed about genetic testing, 51.4% ± 2.25% strongly or somewhat disagreed. No significant relationship was noted between year of graduation and feeling well informed. Although 57.2% ± 2.29% of respondents said they received genetics training in medical school, 73.0% ± 2.01% felt this training was inadequate to order or use genetic tests. Respondents ordered genetic testing for disease susceptibility or diagnosis once or twice a year, 3 to 10 times/year, or never (38.2% ± 2.23%, 30.2% ± 2.11%, and 32% ± 2.15%, respectively). Being comfortable with ordering a genetic test to diagnose a disease was expressed by 45.7% ± 2.24%, but 38.7% ± 2.18% strongly or somewhat disagreed. For ordering a test to predict disease susceptibility, 38.8% ± 2.19% strongly or somewhat agreed, and 43.7% ± 2.22% strongly or somewhat disagreed. Most respondents (72.7% ± 1.99%) had heard of PGx testing before they completed the survey; 22% ± 1.77% reported they had not received any education about PGx. Respondents in family medicine were more likely to have received no education about PGx compared with internists (27.9% vs 17.0%; P = 0.003). Most respondents indicated they learned about PGx through journals or professional meetings, CME, or grand rounds. Respondents thought that CME or grand rounds were the best approach for education about PGx testing (36.5% ± 2.23%) followed by residency training (15.5% ± 1.67%). Most respondents (76.2% ± 2.01%) were not aware that the Food and Drug Administration had revised drug labels to include PGx information. Most agreed that PGx testing could be a valuable tool to predict risks of adverse events or likelihood of effectiveness, but 36% ± 2.06% indicated they would be more likely to order a comparable nongenetic PGx test if one were available. Most respondents (62.9% ± 2.35%) believed that they should have primary responsibility for making patients aware of an appropriate PGx test. A disease specialist/genetics professional should have primary responsibility for determining which PGx variants should be included in the testing panel (24.9% ± 2.10% and 33.4 ± 2.30%, respectively), but it was the PCP’s responsibility to discuss PGx test results with the patient (57.5% ± 2.32%). Most (91.6% ± 1.23%) said they would refer a patient to a genetic specialist for information about familial implications. Ten percent indicated that pharmacists should have primary responsibility for determining the appropriate drug selection or dose based on PGx test results.
These results indicate that the main barrier for use is the lack of education about PGx testing. Most respondents believe PGx testing is valuable and see a major role for PCPs regarding patient education, delivery, and communication of test results. A partnership with geneticists or pharmacists may be beneficial to PCPs and their patients. Developing effective tools for guiding PCPs in the use of PGx tests should be a high priority.