Beliefs about generic drugs among elderly adults in hospital-based primary care practices

doi:10.1016/j.pec.2008.07.012

Patient Educ Couns. Author manuscript; available in PMC 2009 November 1.

Published in final edited form as:

Patient Educ Couns. 2008 November; 73(2): 377–383.

doi: 10.1016/j.pec.2008.07.012

PMCID: PMC2739237

NIHMSID: NIHMS130472

Beliefs about generic drugs among elderly adults in hospital-based primary care practices

Alice Iosifescu,^a Ethan A. Halm,^b Thomas McGinn,^b Albert L. Siu,^c^d and Alex D. Federman^b^*

^aMount Sinai School of Medicine, One Gustave Levy Place, New York, NY 10029, United States

^bDivision of General Internal Medicine, Mount Sinai School of Medicine, New York, NY, United States

^cBrookdale Department of Geriatrics and Adult Development, Mount Sinai School of Medicine, New York, NY, United States

^dGeriatric Research, Education, and Clinical Center, Bronx Veterans Affairs Medical Center, Bronx, NY, United States

^*Corresponding author at: Division of General Internal Medicine, Mount Sinai School of Medicine 1 Gustave L. Levy Place Box 1087 New York, NY 10029 United States. Tel.: +1 212 824 7565; fax: +1 212 831 8116. E-mail address: alex.federman/at/mssm.edu (A.D. Federman).

The publisher's final edited version of this article is available at Patient Educ Couns

See other articles in PMC that cite the published article.

Abstract

Objective

This study aimed to characterize seniors’ beliefs about generic drugs, and examine potential correlates of these beliefs, including socioeconomic and health status variables, health literacy, and physician communication skills.

Methods

Older adults (≥65 years) were interviewed in two primary care practices of an inner-city, tertiary care hospital (n = 311). Beliefs about generics were measured using a scale that compared generic and brand name drugs across four domains. Beliefs were modeled with multivariable linear regression.

Results

Negative beliefs about generics were associated with non-white race (p < 0.0001), lower education (p = 0.008) and income (p = 0.001), and having Medicaid coverage (p = 0.001). Individuals with low health literacy and who reported that their physicians had poor communication skills were more likely to hold negative views (p < 0.0001 and p = 0.003, respectively). In multivariable analysis, black race (β = -2.30, p = 0.006) and inadequate health literacy (β = -2.17, p = 0.0004) remained strongly associated with negative views about generic drugs. Poor physician communication skills also predicted negative beliefs about generics but the association was not significant for all levels of communication skill.

Conclusion

Many low-income seniors mistrust generic medications, especially African-Americans and seniors with low health literacy.

Practice implications

Educational efforts to promote generic medications should account for patients’ health literacy and cultural backgrounds.

Keywords: Generic drugs, Beliefs, Elderly, Low-income, Access to care

1. Introduction

The majority of older adults in United States obtain their prescription medications through private health or prescription plans, each of which introduces different cost-sharing arrangements for patients. In most plans, and certainly for older adults who lack prescription drug coverage, generic medications are important alternatives to costly brand name drugs and present low-income adults with opportunities to reduce their out-of-pocket expenditures on healthcare. Despite the financial benefits of substituting generics for brand names agents, low-income seniors often are given brand name drugs when opportunities for generic substitution exist. For example, we recently reported that 20% of low-income seniors with cardiovascular diseases used a brand name cardiovascular drug when the identical drug was available as a generic [1]. A host of patient, provider and system factors may contribute to relative differences in the use of generic and brand drugs. These include, but are not limited to, physician prescribing preferences and habits, mandatory generic substitution laws, and drug formularies. Since patient preferences are a powerful motivator of physician prescribing practices [2,3], beliefs about generic drugs may be a particularly potent factor influencing receipt of prescriptions for brand or generic drugs.

Patients may prefer brand name drugs to generics for a number of reasons. One of the most important factors may be direct to consumer (DTC) advertising of brand name drugs, which is permitted in USA, is heavily used [4], and has a potent influence on public perceptions of medications. DTC advertisements provide favorable and imbalanced pictures of medications, often portraying them as important medical breakthroughs [5], resulting in high levels of brand recognition and loyalty [6]. In USA and elsewhere, physicians’ preferences for particular brand name agents, or a bias against generics, may in turn influence patients’ attitudes about these drugs [7]. Insurers, government agencies and others have used informational campaigns to promote generic medication use, but such efforts pale in comparison to the $4 billion annual—and increasing—brand name drug promotion efforts of the pharmaceutical industry [4]. Despite an expansive literature on DTC advertising and medication utilization, little is known about how patients view generic and brand name drugs.

To better understand patients’ perspectives on generic medications, we examined beliefs about generics among older adults attending two hospital-based general medicine practices situated in an inner-city, low-income community. This subject is well suited for study among low-income seniors because their low, fixed incomes and high levels of illness burden result in substantial financial stress and high rates of medication avoidance owing to cost [1,8,9], thereby enhancing the potential value of generic drugs. We were particularly interested in determining whether variables associated with lower ability to access and process information about generic drugs, such as low education and heath literacy, and poor physician communication skills, would be associated with negative beliefs about generics. Similarly, we reasoned that because of the potential cost-savings associated with the use of generic drugs, we sought to determine whether factors that might create greater healthcare-related financial pressures, such as low-income, poor health status, and high levels of prescription medication use, would be associated with more favorable views of generics.

2. Methods

2.1. Setting and subjects

Data used for this analysis were collected as part of a study of physician-patient communication about cost of care. We recruited adults aged 65 years and older who were enrolled in Medicare, the federal health insurance program for elderly and disabled adults in USA, and who lacked a diagnosis of dementia. Recruitment took place between July 2005 and August 2006 in the primary care and geriatrics outpatient practices of an 1100-bed, tertiary care academic medical center. These practices serve the predominantly low-income population of East Harlem, New York City, NY. During the period of study, pharmaceutical manufacturer representatives were not allowed to conduct drug detailing in the outpatient internal medicine and geriatrics practices, and prescription drug samples were not available. Eligible subjects were identified by review of electronic billing records and a random selection of individuals was approached by bilingual (Spanish and English) research staff in the clinic waiting areas. The 1-h interview was administered in English or Spanish and participants received $20. The study was approved by the Mount Sinai School of Medicine Institutional Review Board.

2.2. Outcome measures

Beliefs about generic medications were measured using a scale composed of four domains. The domains were identified and refined through focus groups and cognitive interviewing conducted with individuals recruited from the same clinics, as well as individuals recruited from community sites in East Harlem. These domains are efficacy, safety, tolerability, and ease of use. Each domain was represented by a single question that assessed belief about the equivalence of generic and brand name drugs on a 5-point Likert scale (strongly agree to strongly disagree). The survey items were preceded by a statement intended to orient respondents to the term ‘generic’: “A generic drug is a medication that has the same ingredients as the original, or brand name drug.” A summary score, the beliefs about generics scale, was created by the addition of responses to each item (range, 4-20). Responses to the questions were coded so that lower scores indicate more negative beliefs about generic drugs.

Cronbach’s alpha for the 4-item scale was 0.79. We considered a fifth domain, differential cost of generic and brand name drugs, but we excluded it from the final scale. The majority of respondents (77.0%) agreed that generic drugs were less expensive than brand name drugs, while greater variation was observed for the four items in the final scale. Indeed, a 5-item scale that included the cost domain had a lower Cronbach’s alpha than the 4-item scale (0.73). Moreover, the cost domain item had low inter-item correlation coefficients (ICCs) with the other four domains (0.05-0.16) whereas ICCs among the other four items ranged from 0.34 to 0.75. Two items, asked among a subset of 100 individuals in the study cohort, were used to assess the construct validity of the scale: patient preference for brand name medications and self-reported requests for brand name drugs in the prior 6 months.

2.3. Independent variables

The primary independent variables of interest were those that represent cost pressures that might influence preference for generic drugs and those that might affect their patients’ understanding of generic drugs. We assessed variables that might drive a person’s need to use generics, including household income, insurance status, out-of-pocket prescription medication expenditures, total number of prescription medications used, a single item measure of general health [10], total number of chronic diseases, and functional status.

Insurance status was dichotomized as Medicaid vs. other, since approximately half of older adults in these clinical practices have Medicaid, the combined state-federal health insurance program for indigent patients. Medicare beneficiaries may also have Medicaid if they meet the income and assets criteria for the program. Functional status was measured using two 5-item assessments of basic and instrumental activities of daily living (ADL and IADL, respectively) [11]. Although individuals who use a large number of generic medications may have reduced prescription drug spending, we reasoned that many drugs would not be available as generics, so that total out-of-pocket prescription spending would be a reasonable measure of the burden of prescription costs regardless of a person’s preference for generic or brand name agents. Since self-reported healthcare expenditures are often inaccurate [12], we also reasoned that inclusion of measures of health and functional status would provide us with a better adjustment for the financial pressures driving generic drug use than by self-reported drug expenditures alone.

The variables we included that might influence a person’s understanding of generic medications were age, English language skill, education, health literacy, and patients’ reports of their physicians’ communication skills. English language skill was assessed using a question that asks “How would you describe your ability to speak and understand English?” The six response options range from very poor to excellent. Health literacy was measured using the short test of functional health literacy in adults (S-TOFHLA) [13]. Scores on the S-TOFHLA correspond to three levels of health literacy: adequate, marginal and inadequate. Individuals with inadequate health literacy struggle with basic medical information, such as reading prescription bottles [13]. Physician communication skill was measured using a previously validated 5-item instrument that asks patients to rate the communication skills of their physicians on a 6-point Likert scale (PCOM) [14]. Among the five items, patients are asked to rate their physician’s skill at giving instructions about taking medications and explaining their health problems and treatments. Higher scores indicate better physician communication. Other variables we considered included sex, race and ethnicity.

2.4. Statistical analysis

We tested the statistical association of scores on the 4-item scale of beliefs about generics with individual covariates using ANOVA. We then modeled scores using multivariable ordinary least squares (OLS) regression, and included all variables in the model. All analyses were conducted using SAS version 9.1 statistical software (SAS Institute, Cary, NC).

3. Results

The study included data on 315 adults aged 65 years and older, representing a recruitment rate of 43%. Comparison of respondents and non-respondents was possible for a limited number of variables. Those who declined to participate were similar to those included in the study in age (77.1 years vs. 73.7 years, p = 0.27), gender (74.3% vs. 76.3% female, p = 0.51), and ethnicity (49.3% vs. 51.6% Hispanic, p = 0.52). The percent of African-Americans who declined (33.1%) and those who participated (16.4%) was different (p < 0.0001).

Among study participants, more than half (50.1%) had house-hold incomes at or below $750 per month, and more than half (59.9%) had Medicaid coverage (Table 1). As expected with patients seen in a hospital-based outpatient practice, poor health and heavy illness burden were common. Sixty percent reported fair or poor general health and 26.8% reported having five or more chronic illnesses. Although 51.1% reported routinely using six or more prescription medications, only 12.3% reported out-of-pocket prescription costs in excess of $100 per month due to the predominance of Medicaid beneficiaries in the study sample.

Table 1

Patient characteristics (n = 315)

3.1. Scale performance

The 4-item scale of beliefs about generics had a mean of 14.2 (S.D. 4.0), median of 14 (range 4-20), and followed an approximately normal distribution (kurtosis -0.35 and skewness -0.35). The mean belief score was not significantly higher after January 1, 2006 when USA implemented the voluntary prescription drug benefit (Medicare Part D) for older (≥65 years) and disabled adults in the federal Medicare health insurance program (pre- vs. post-implementation of Part D, mean score 13.9 (4.1) vs. 14.5 (4.0); p = 0.21). The scale demonstrated concurrent validity: having a preference for brand name medications and having requested a brand name agent were both significantly associated with negative beliefs about generic drugs (p = 0.0001 and p = 0.02, respectively).

3.2. Beliefs about generic drugs

Table 2 shows the frequency of responses to each item used to assess beliefs about generics. Fewer than half of respondents reported that generics are as effective or as safe as brand name drugs or have the same number of side effects. In contrast, only 3.8% of respondents disagreed that generics are less expensive than brand name drugs. Many study participants were uncertain about whether generic and brand name drugs are equivalent in terms of effectiveness, safety, ease of use, side effects, and cost. For example, 19.4% were uncertain whether generics were less expensive than brand name drugs and 41.8% were uncertain whether generics have more side effects.

Table 2

Self-reported beliefs about generic drugs (n = 315)

Unfavorable views of generic medications were more common among those of lower socioeconomic status (Table 3). Unfavorable views were associated with non-white race, lower education, lower levels of health literacy and lower income, having Medicaid, worse functional status, and worse physician communication scores. Age, sex, English language proficiency, health status, and out-of-pocket prescription drug spending were not statistically associated with views about generic drugs.

Table 3

Multivariable analysis of correlates of generic drug beliefs

In multivariable linear regression analysis (Table 3), only black race and inadequate health literacy were significantly associated with negative beliefs about generics (black race, β = -2.00, p = 0.03; inadequate health literacy, β = -2.06, p = 0.001). Poor physician communication skill was associated with negative beliefs about generics, although the association did not achieve statistical significance at all levels of communication scores.

Table 4 shows the domains of the beliefs about generic drugs scale, as well as beliefs about generic drug costs, stratified by level of health literacy. In this analysis we dichotomized the belief domains as disagree vs. uncertain or agree to facilitate interpretation of the data. Health literacy was significantly associated with all domains of beliefs about generic drugs. Individuals with inadequate health literacy were nearly half as likely to question their effectiveness and half as likely as those with marginal or adequate health literacy to say that generics are as safe as brand name drugs.

Table 4

Percent agreement with statements about generic drugs, stratified by health literacy

These associations remained statistically significant in multivariable logistic regression analyses (Table 5). Individuals with inadequate health literacy had less than half the odds of those with adequate health literacy of reporting that generics work as well as brand name drugs. In other words, study participants with inadequate health literacy were more likely to question the effectiveness of generic drugs. They were also more likely to agree that generics have more side effects than brand name drugs.

Table 5

Adjusted association of health literacy with individual beliefs about generic drugs

Regarding racial differences in beliefs about generic medications, black adults were significantly less likely than whites to state that generics work as well as brand name drugs (adjusted OR 0.28, 95% CI 0.10-0.79, p = 0.02). They were also less likely to say that generics are as safe as brand name drugs (adjusted OR 0.38, 95% CI 0.14-1.05, p = 0.06) and more likely to say that generics are more difficult to take (adjusted OR 2.78, 95% CI 0.94-8.19, p = 0.06), though these associations did not reach the level of statistical significance. In adjusted analyses, black race was not significantly associated with beliefs about the costs or side effects associated with associated generic drugs.

4. Discussion and conclusion

4.1. Discussion

In this sample of low-income, racially and ethnically mixed seniors, unfavorable opinions about generic medications were common. While most seniors recognized that generics are less expensive than brand name agents, one-in-four believed that generics are less effective and one-in-five believed that generics are less safe. Furthermore, between 20 and 40% of seniors were uncertain whether generic drugs were equivalent to brand name drugs across the five domains of drug characteristics we studied. Importantly, we found that individuals with low health literacy were more likely to hold negative views of generic medications, even after accounting for income, insurance, medication spending and other socioeconomic and health status variables. In contrast, and consistent with our findings from analyses of nationally representative datasets [1,15], variables that would seemingly increase one’s need to save money on medications were not significantly associated with beliefs about generics. These variables included lower income, poor health, and high out-of-pocket prescription drug spending.

Previous research has shown an association between education level and understanding about generic medications, and demonstrates that counseling patients about generics results in greater use of these drugs [16-19]. With limited exceptions, however, the literature has not identified specific concerns about generics among older patients. Studies in Germany and Canada have shown that some patients consider generic drugs, warfarin for example, riskier to use than brand name drugs [16,20]. Our study moves beyond this earlier work by identifying specific concerns about generics. We show that safety, effectiveness, tolerability, and ease of use of generic medications are common areas of concern among patients that may underlie reluctance to use generics, even among patients experiencing financial hardship from their medication costs. These concerns should be focal points of interventions to promote acceptance of generic drugs.

The association between health literacy and beliefs about generic medications may be connected to patients’ understanding of written information on generics, such as generic drug promotions. Patients’ ability to navigate through healthcare systems and manage their chronic health problems is strongly associated with their health literacy skills [21-24]. By extension, media campaigns intended to promote generic drugs may have little impact on generic medication use unless they account for the health literacy levels of the target population. Direct to consumer advertising may also explain the association between health literacy and generic medication beliefs. In United States, pharmaceutical manufacturers often use radio and television to advertise drugs directly to seniors. Such advertising may have a disproportionately strong effect on low-literate patients.

The problem of health literacy and generic medication beliefs highlights the important role of the physician in clearly communicating information about generic drugs with their patients. Indeed, we found that patients of physicians with poor communication skills also had more negative views of generic drugs. Because physicians have the primary responsibility for educating patients about medications, those who communicate poorly with patients may not share important information about generic drugs, thus providing a possible explanation for this observed association between physician communication skill and patients’ beliefs about generics. Patients with inadequate health literacy have difficulty in understanding spoken as well as written medical information [25], so they may be particularly prone to missing important messages about medications from doctors who communicate poorly.

Our finding of an association between black race and negative beliefs about generics is in keeping with previous studies, which suggest that patients from minority groups report overall lower levels of satisfaction with their health care [26,27]. In one study, members of minority groups reported lower trust in their physicians, and lower satisfaction with their physician’s style compared with whites [27]. Another study indicated that African-American patients rate their doctor’s visits as less participatory than whites [26]. Our data demonstrated that blacks held negative beliefs about generics after controlling for confounding factors such as physician communication, physician trust, physician participatory decision-making style, education and other socioeconomic factors. The negative opinion of generics was unrelated to the quality of their relationship with their doctors. The reason for this belief should be addressed by providers, researchers, and insurers looking to understanding and encourage generic drug use.

It is important to acknowledge the potential impact of Medicare Part D on beliefs and use of generic drugs by the seniors in USA. Medicare Part D is the voluntary prescription drug program available to adults in Medicare. Medicare Part D is administered through private health and prescription drug plans, which apply various cost-sharing mechanisms to encourage generic substitution. Changes in formularies that emphasize generic medications generally achieve the intended effect of increasing uptake of generic or preferred brand name agents [28,29]. It is possible that increased use of generics resulting from financial incentives to do so could generate more favorable views of these medications over time. While we found no significant difference in attitudes about generics before and after the implementation of Medicare Part D, our post-implementation data may have been collected too early to allow for changes in beliefs to occur. It is also important to note that Medicare Part D was implemented approximately midway through the course of our study. However, efforts by drug plans to encourage generic medication use have backfired. Health plan members often discontinue their medications when faced with formulary changes that force them to switch to generic drugs [28,29], and new uptake of generics has fallen short of its full potential [1,30-34], with estimates of unrealized savings on prescription drugs as high as $8.8 billion [33,35]. Identifying and addressing patients’ concerns about generic drugs may help patients reduce out-of-pocket spending on medications, as well as bringing private and public insurers closer to achieving their generic substitution goals.

Our study must be interpreted in the light of its methodological limitations. First, although we used a validated measure of health literacy, this measure could be a proxy for latent variables associated with beliefs and socioeconomic status. We did, however, include a number of SES measures in our study and our health literacy measure remained significantly associated with beliefs about generic drugs despite these adjustments. Second, most patients in the study had Medicaid and may be less sensitive to the cost of medications than other low-income adults who must pay more out-of-pocket for their medications. Third, the study was conducted at a single institution and had a low recruitment rate. These factors limit the generalizability of the results. The study sample, nonetheless, was represented by individuals of differing ages, education levels, insurance types, health status, health literacy, and beliefs about generic drugs. Fourth, while our scale of beliefs about generic drugs demonstrated good inter-item correlation and concurrent validity, it only included one item per domain and may not be optimally sensitive to meaningful variations in attitudes about generics. Further, it was developed and validated in a population of predominately low-income, Hispanic and African-American seniors. It should be validated in demographically different patient populations before it is used elsewhere. Data on physician communication skills are also limited because they are reported by the patient and therefore represent patients’ perceptions. They may not represent actual communication skills of the physician.

Fifth, we did not measure actual generic medication use so we cannot conclude that the expressed beliefs about generic drugs accurately reflect utilization patterns. Some individuals may be concerned about generic medications but continue to use them, for example, as a result of financial pressures. Sixth, and lastly, the study was conducted during the early phases of the Medicare Part D implementation. Beliefs about generic drugs may have changed as more seniors are exposed to them through plan formularies. We did, however, compare beliefs about generics before and after Part D was introduced and found no difference in belief scores.

4.2. Conclusions

We find that many seniors from a low-income, hospital-based, inner-city clinical practice have negative beliefs about generic drugs, and that negative beliefs are more common among African-American patients, those with lower health literacy, and among those whose physicians have poor communication skills. As suggested by our data, information about the safety and effectiveness of generic drugs may be particularly important information to convey to patients.

4.3. Practice implications

Although many stakeholders promote methods such as teach back (wherein physicians ask patients to restate, using their own words, the information the physician just gave them) to ensure better understanding of healthcare instructions among low-literate patients [36], this method may not influence attitudes and beliefs about generic drugs. Yet, at a minimum, doctors should take the initiative to ask patients about cost-related concerns because patients often avoid discussing out-of-pocket costs with their doctors [37,38]. They can use such opportunities to highlight the financial benefit of generic medication use while addressing misconceptions about these drugs. Additionally, future efforts to promote generic medication use should focus on addressing concerns about the safety, effectiveness, tolerability, and ease of use of generic medications, using simple messages that account for the health literacy levels of the target population. Research is needed to confirm and elucidate the association between race and beliefs about generics observed in our study.

Acknowledgements

The authors thank Dr. Deborah Korenstein for her comments on the manuscript. Data from this study were presented at the annual meetings of the American Geriatrics Society (5 May, 2007; Seattle, WA) and the Society of General Internal Medicine (27 April, 2007; Toronto, Canada).

Funding: This project was supported by a Robert Wood Johnson Generalist Physician Faculty Scholars Program Award (Dr. Federman). Dr. Federman also receives support from the Paul B. Beeson Career Development Award Program in Aging from the National Institute on Aging and the American Federation for Aging Research. Ms. Iosifescu’s work on this project was supported by a Medical Student Training in Aging Research (MSTAR) Program award from the American Federation for Aging Research.

Role of the sponsor: The sponsor played no role in the collection, analysis and interpretation of data; writing of the report; or the decision to submit the paper for publication. Dr. Federman 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.

Footnotes

Conflict of interest

The authors have no conflicts of interest to disclose.

References

[1] Federman AD, Halm EA, Zhu C, Hochman T, Siu AL. Association of income and prescription drug coverage with generic medication use among older adults with hypertension. Am J Manage Care. 2006;12:611–8. [PMC free article] [PubMed]

[2] Barrett L., AARP Physicians’ Attitudes And Practices Regarding Generic Drugs. Mar, 2005.

[3] Kravitz RL, Epstein RM, Feldman MD, Franz CE, Azari R, Wilkes MS, Hinton L, Franks P. Influence of patients’ requests for direct-to-consumer advertised antidepressants: a randomized controlled trial. J Am Med Assoc. 2005;293:1995–2002. [PMC free article] [PubMed]

[4] Gellad ZF, Lyles KW. Direct-to-consumer advertising of pharmaceuticals. Am J Med. 2007;120:475–80. [PubMed]

[5] Frosch DL, Krueger PM, Hornik RC, Cronholm PF, Barg FK. Creating demand for prescription drugs: a content analysis of television direct-to-consumer advertising. Ann Fam Med. 2007;5:6–13. [PubMed]

[6] Mintzes B, Barer ML, Kravitz RL, Kazanjian A, Bassett K, Lexchin J, Evans RG, Pan R, Marion SA. Influence of direct to consumer pharmaceutical advertising and patients’ requests on prescribing decisions: two site cross sectional survey. Br Med J. 2002;324:278–9. [PMC free article] [PubMed]

[7] Banahan BF, III, Kolassa EM. A physician survey on generic drugs and substitution of critical dose medications. Arch Intern Med. 1997;157:2080–8. [PubMed]

[8] Piette JD, Heisler M, Wagner TH. Problems paying out-of-pocket medication costs among older adults with diabetes. Diabetes Care. 2004;27:384–91. [PubMed]

[9] Wilson IB, Rogers WH, Chang H, Safran DG. Cost-related skipping of medications and other treatments among Medicare beneficiaries between 1998 and 2000. Results of a national study. J Gen Intern Med. 2005;20:715–20. [PMC free article] [PubMed]

[10] DeSalvo KB, Fan VS, McDonell MB, Fihn SD. Predicting mortality and healthcare utilization with a single question. Health Serv Res. 2005;40:1234–46. [PMC free article] [PubMed]

[11] Lawton MP, Brody EM. Assessment of older people: self-maintaining and instrumental activities of daily living. Gerontologist. 1969;9:179–86. [PubMed]

[12] Poisal JA. Reporting of drug expenditures in the MCBS. Health Care Financ Rev. 2004;25:1–4. [PubMed]

[13] Baker DW, Williams MV, Parker RM, Gazmararian JA, Nurss J. Development of a brief test to measure functional health literacy. Patient Educ Couns. 1999;38:33–42. [PubMed]

[14] Heisler M, Bouknight RR, Hayward RA, Smith DM, Kerr EA. The relative importance of physician communication, participatory decision making, and patient understanding in diabetes self-management. J Gen Intern Med. 2002;17:243–52. [PMC free article] [PubMed]

[15] Federman AD, Halm EA, Siu AL. Use of generic cardiovascular medications by elderly Medicare beneficiaries receiving generalist or cardiologist care. Med Care. 2007;45:109–15. [PubMed]

[16] Himmel W, Simmenroth-Nayda A, Niebling W, Ledig T, Jansen RD, Kochen MM, Gleiter CH, Hummers-Pradier E. What do primary care patients think about generic drugs? Int J Clin Pharmacol Ther. 2005;43:472–9. [PubMed]

[17] Pereira JA, Holbrook AM, Dolovich L, Goldsmith C, Thabane L, Douketis JD, Crowther M, Bates SM, Ginsberg JS. Are brand-name and generic warfarin interchangeable? A survey of Ontario patients and physicians. Can J Clin Pharmacol. 2005;12:e229–39. [PubMed]

[18] Valles JA, Barreiro M, Cereza G, Ferro JJ, Martinez MJ, Escriba JM, Iglesias B, Cucurull E, Barcelo E. A prospective multicenter study of the effect of patient education on acceptability of generic prescribing in general practice. Health Policy. 2003;65:269–75. [PubMed]

[19] Van Wijk BL, Klungel OH, Heerdink ER, de Boer A. Generic substitution of antihypertensive drugs: does it affect adherence? Ann Pharmacother. 2006;40:15–20. [PubMed]

[20] Ganther JM, Kreling DH. Consumer perceptions of risk and required cost savings for generic prescription drugs. J Am Pharm Assoc (Wash) 2000;40:378–83. [PubMed]

[21] Gazmararian JA, Baker DW, Williams MV, Parker RM, Scott TL, Green DC, Fehrenbach SN, Ren J, Koplan JP. Health literacy among Medicare enrollees in a managed care organization. J Am Med Assoc. 1999;281:545–51. [PubMed]

[22] Gazmararian JA, Williams MV, Peel J, Baker DW. Health literacy and knowledge of chronic disease. Patient Educ Couns. 2003;51:267–75. [PubMed]

[23] Schillinger D, Grumbach K, Piette J, Wang F, Osmond D, Daher C, Palacios J, Sullivan GD, Bindman AB. Association of health literacy with diabetes outcomes. J Am Med Assoc. 2002;288:475–82. [PubMed]

[24] Wolf MS, Gazmararian JA, Baker DW. Health literacy and functional health status among older adults. Arch Intern Med. 2005;165:1946–52. [PubMed]

[25] Schillinger D, Machtinger EL, Wang F, Palacios J, Rodriguez M, Bindman A. Language, literacy, and communication regarding medication in an anticoagulation clinic: a comparison of verbal vs. visual assessment. J Health Commun. 2006;11:651–64. [PubMed]

[26] Cooper-Patrick L, Gallo JJ, Gonzales JJ, Vu HT, Powe NR, Nelson C, Ford DE. Race, gender, and partnership in the patient-physician relationship. J Am Med Assoc. 1999;282:583–9. [PubMed]

[27] Doescher MP, Saver BG, Franks P, Fiscella K. Racial and ethnic disparities in perceptions of physician style and trust. Arch Fam Med. 2000;9:1156–63. [PubMed]

[28] Goldman DP, Joyce GF, Zheng Y. Prescription drug cost sharing: associations with medication and medical utilization and spending and health. J Am Med Assoc. 2007;298:61–9. [PubMed]

[29] Huskamp HA, Deverka PA, Epstein AM, Epstein RS, McGuigan KA, Frank RG. The effect of incentive-based formularies on prescription-drug utilization and spending. N Engl J Med. 2003;349:2224–32. [PubMed]

[30] Federman AD, Arnsten JA. Primary care affiliations of adults in a methadone program with onsite care. J Addict Dis. 2007;26:27–34. [PubMed]

[31] Fischer MA, Avorn J. Economic consequences of underuse of generic drugs: evidence from Medicaid and implications for prescription drug benefit plans. Health Serv Res. 2003;38:1051–63. [PMC free article] [PubMed]

[32] Fischer MA, Avorn J. Potential savings from increased use of generic drugs in the elderly: what the experience of Medicaid and other insurance programs means for a Medicare drug benefit. Pharmacoepidemiol Drug Safe. 2004;13:207–14. [PubMed]

[33] Haas JS, Phillips KA, Gerstenberger EP, Seger AC. Potential savings from substituting generic drugs for brand-name drugs: medical expenditure panel survey, 1997-2000. Ann Intern Med. 2005;142:891–7. [PubMed]

[34] Iglehart JK. Prescription-drug coverage for Medicare Beneficaries. N Engl J Med. 2003;349:923–5. [PubMed]

[35] Ettner SL, Hermann RC. Inpatient psychiatric treatment of elderly Medicare beneficiaries. Psychiatr Serv. 1998;49:1173–9. [PubMed]

[36] Paasche-Orlow MK, Schillinger D, Greene SM, Wagner EH. How health care systems can begin to address the challenge of limited literacy. J Gen Intern Med. 2006;21:884–7. [PMC free article] [PubMed]

[37] Alexander GC, Casalino LP, Tseng CW, McFadden D, Meltzer DO. Barriers to patient-physician communication about out-of-pocket costs. J Gen Intern Med. 2004;19:856–60. [PMC free article] [PubMed]

[38] Alexander GC, Werner RM, Fagerlin A, Ubel PA. Support for physician deception of insurance companies among a sample of Philadelphia residents. Ann Intern Med. 2003;138:472–5. [PubMed]