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Figure.  Predicted Probabilities of Generic Drug Discount Program Use
Predicted Probabilities of Generic Drug Discount Program Use

A, Age groups, determined as younger adults (aged 18-45 years), older adults (aged 46-64 years), and seniors (aged ≥65 years). B, Presence of health insurance. C, Drug therapy complexity, as measured by the number of drugs in use. D, Comorbidities, as measured by the Charlson Comorbidity Index. E, Race/ethnicity. F, Family income in relationship to the FPL. Probabilities were predicted for each group with adjustments for variables according to Andersen’s3 behavioral model at their mean value. FPL indicates federal poverty level; HSP, Hispanic; NHB, non-Hispanic black; and NHW, non-Hispanic white. Bars indicate means; limit lines, 95% CIs.

Table.  Characteristics of GDDP Users vs Nonusers in 2010a
Characteristics of GDDP Users vs Nonusers in 2010a
Research Letter
November 2014

Uptake of Generic Drug Discount Program Among Vulnerable Populations

Author Affiliations
  • 1Health Outcomes and Policy Research, Department of Clinical Pharmacy, College of Pharmacy, University of Tennessee Health Science Center, Memphis
  • 2College of Nursing, University of Memphis, Memphis, Tennessee
JAMA Intern Med. 2014;174(11):1858-1860. doi:10.1001/jamainternmed.2014.4497

The generic discount drug program (GDDP) that allows patients to pay nominal fees ($4) for filling prescriptions with generic drugs was introduced in 2006 by Walmart. The program can reduce medication costs and help patients to access their needed drug therapy, especially the elderly, poor, sicker, and racial/ethnic minority populations. However, the initial uptake of the GDDP in 2007 was low, at 3.6% of patients receiving any prescription drugs, especially among racial/ethnic minorities.1 The lower initial uptake of the GDDP among racial/ethnic minorities raises the question: why would patients who gain more from GDDPs be less likely to use them? We aimed to determine whether the uptake of the GDDP increased as the program matured and to examine whether factors affecting the uptake of the GDDP have remained steady over time.


The Medical Expenditure Panel Survey is a nationally representative longitudinal household survey of health care use and expenditures for noninstitutionalized US civilians.2 The present study used 2010 Household Component and Prescribed Medicines files, which included information on the drug name, days of supply, and amount paid. Information on days of supply was not available before 2010. The institutional review board of the University of Tennessee Health Science Center approved the study and waived the need for informed consent.

The study evaluated adults (aged >18 years) who had received at least 1 prescription drug in 2010. Users of the GDDP were defined as individuals who had used the GDDP at least once. If a prescribed medicine event had the total amount paid and days of supply equivalent to any GDDP offerings, the GDDP was coded as 1 (the coding was otherwise 0). Typical GDDP offerings were $4 for 30-day supplies and $10 for 90-day supplies as provided by Walmart, Target, and Kroger. Rite Aid, CVS, Walgreens, and Kmart had other GDDP offerings.

Andersen’s3 behavioral model was used to identify factors associated with use of the GDDP. The logistic regression procedure in SAS, version 9.4 (SAS Institute Inc), was used to predict probabilities for different patient groups while controlling for complex survey sampling. We assumed that all prescription drug users had an opportunity to use the GDDP. We also assumed that physician prescribing behaviors, pharmacist practice styles, and pharmacy benefit designs occurred independently of each factor affecting use of the GDDP.


Of the 13 486 adults who had at least 1 prescription drug event in 2010, 3208 were GDDP users (Table); the weighted rate of GDDP use was 23.1%. Use of the GDDP was more likely among the elderly, sicker, and uninsured groups (Figure). Use of the GDDP was also more likely among people living in rural areas and central regions of the United States. However, the rate of GDDP use was not significantly different across different educational level, income, and racial/ethnic groups.


Use of the GDDP noticeably increased as the program matured. The increase may well be the result of expansion of pharmacy chains offering GDDPs and consumer awareness of the programs. As expected, GDDPs were more valued among the elderly, sicker, and uninsured populations. However, GDDPs were equally valued across different educational level, income, and racial/ethnic groups. In other words, GDDPs were not considered inferior despite the common perception that generic drugs are of poor quality.4 In fact, GDDPs offer convenience by not requiring insurance claims to be filed.

The lower use of GDDPs among racial/ethnic minorities observed when the program was deployed1 no longer existed when the program matured. Individuals within this population may have taken longer to adopt the GDDP because they lacked health insurance literacy (ie, one study reported this deficiency as a reason for the lackluster participation in the health insurance marketplace5). However, the GDDP does not involve complex concepts of health insurance. Alternatively, individuals among racial/ethnic minorities may have lacked broadband access to gain firsthand knowledge of GDDP deployment.6

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Article Information

Corresponding Author: Song Hee Hong, PhD, Health Outcomes and Policy Research, Department of Clinical Pharmacy, College of Pharmacy, Room 219, University of Tennessee Health Science Center, 881 Madison Ave, Memphis, TN 38163 (shhong@uthsc.edu).

Conflict of Interest Disclosures: None reported.

Published Online: September 22, 2014. doi:10.1001/jamainternmed.2014.4497.

Author Contributions: Drs Hong and Tak had full access to all the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.

Study concept and design: Hong.

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

Drafting of the manuscript: Hong.

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

Statistical analysis: Hong.

Administrative, technical, or material support: All authors.

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