Prevalence and Predictors of Generic Drug Skepticism Among Physicians: Results of a National Survey

Generic drugs are low-cost, therapeutically equivalent versions of brand-name drugs. Use of generic drugs increases patient adherence and improves health outcomes.¹ However, a 2009 survey of physicians showed that 23% disagreed that generic drugs were as effective as brand-name drugs and 50% reported quality concerns, leading more than one-quarter not to recommend generic drugs as first-line therapy.²

Because generic drugs now make up more than 85% of prescriptions,³ we reassessed physicians’ perceptions and determined how professional or demographic characteristics predict physicians’ support of generic drug prescribing.

From a master list of American Board of Internal Medicine diplomates, we randomly selected 300 clinically active internists and 900 specialists in endocrinology, hematology, and infectious diseases (52 excluded for lacking contact information). We emailed the survey link ($50 honoraria), with nonresponders receiving 2 reminders, a mailed version, and a final email reminder (the study was approved by Brigham and Women’s Hospital Institutional Review Board with an authorization agreement from the US Food and Drug Administration Research Involving Human Subjects Committee). Consent was implied based on reading the survey goals and participating. Using 5-point Likert scales, we measured respondents’ perceptions of generic drugs and how they last learned about a newly available generic drug.

Our first outcome variable was generic skepticism, defined as answering neutral or negative to whether generic drugs were as safe and effective as brand-name drugs, or answering neutral or positive to whether generic drugs cause more adverse effects. In sensitivity analyses, we excluded neutral responses. The second outcome variable was self-reported “brand-name–only” prescribing more than 5% of the time.⁴

We assessed response variations among demographic and practice characteristics, using Pearson χ² test and 2-sample t tests. The Wilson method identified confidence intervals for proportions⁵ and logistic regression estimated adjusted associations (Stata, version 13.1; StataCorp).

Among 718 respondents (62.3% response rate), the mean (SD) age was 46 (10) years, 54% (374 of 687) were male, 61% (387 of 639) trained at US medical schools, and 58% (393 of 675) were white. Nonrespondents had a mean (SD) age of 49 (11) years, and 57% (293 of 510) were male.

Generic drugs were widely favored: 638 respondents (89% [95% CI, 86%-91%]) perceived them as effective and 653 (91% [95% CI, 89%-93%]) perceived them to be as safe as their brand-name counterparts, while 523 (73% [95% CI, 70%-76%]) agreed that they do not cause more adverse effects and 500 (70% [95% CI, 66%-73%]) preferred prescribing generic over brand-name drugs (Table 1).

Generic skeptics (32% of sample [227 of 718]) showed no significant variation in demographic or practice characteristics. Approximately half “sometimes,” “rarely,” or “never” knew when generic drugs became available, with 155 (22% [95% CI, 19%-25%]) last learning about generic availability from pharmaceutical representatives (Table 2), a connection significantly associated with generic skepticism (41% [63 of 155] vs 29% [164 of 563]; P = .006).

Approximately 35% reported brand-name-only prescribing more than 5% of the time, with higher rates among physicians who last learned about generic drugs from pharmaceutical representatives (51% [79 of 155] vs 30% [170 of 561]; P < .001), non-US medical school graduates (39% [98 of 252] vs 31% [121 of 387]; P = .047), specialists vs internists (39% [211 of 547] vs 23% [34 of 145]; P = .001), and respondents spending more than 80% of time in patient care (39% [148 of 376] vs 27% [73 of 267]; P = .002).

After restricting the analytic data set to the 612 physicians with complete demographic and practice variables (except type) and adjusting for these variables, learning about availability of a generic drug from a pharmaceutical representative continued its positive association with higher brand-name–only prescribing (47% vs 30%; P < .001), but not with generic skepticism (35% vs 30%; P = .26). Excluding neutral responses from the skepticism definition reduced the proportion to 15% (108 of 718) but affected none of the comparisons.

These results suggest an overall shift in the perceptions of board-certified internal medicine physicians and certain specialists about generic drugs toward greater confidence in their quality and safety. Still, generic skepticism remains common, particularly among physicians who reported pharmaceutical sales representatives as sources of the last times they learned about generic drugs becoming available. While several tests of significance were conducted—increasing the likelihood that at least 1 significant result may be a false positive—our data suggest that limiting interactions with pharmaceutical marketing and directed educational outreach could help ensure that generic drug prescribing remains widespread for the benefit of patients and to help slow the rate of increase of health care costs.

Corresponding Author: Aaron S. Kesselheim, MD, JD, MPH, Department of Medicine, Brigham and Women’s Hospital, 1620 Tremont St, Ste 3030, Boston, MA 02120 (akesselheim@partners.org).

Published Online: May 9, 2016. doi:10.1001/jamainternmed.2016.1688.

Author Contributions: Dr Kesselheim had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Study concept and design: Kesselheim, Gagne, Campbell.

Acquisition, analysis, or interpretation of data: All authors.

Drafting of the manuscript: Kesselheim.

Critical revision of the manuscript for important intellectual content: All authors.

Statistical analysis: Gagne, Eddings, Franklin.

Obtained funding: Kesselheim, Gagne, Campbell.

Administrative, technical, or material support: Gagne, Ross, Fulchino.

Study supervision: Kesselheim, Franklin.

Conflict of Interest Disclosures: None reported.

Funding/Support: This study was funded by a grant (U01FD004856) from the US Food and Drug Administration Office of Generic Drugs.

Role of the Funder/Sponsor: The funder provided comments on an earlier draft and had no role in design and conduct of the study; collection, management, analysis, and interpretation of the data; approval of the final manuscript; and decision to submit the manuscript for publication.