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Influences on consumer spending for herbal products
Research in Social and Administrative Pharmacy 2 (2006) 254–265
Original research
Influences on consumer spending for herbal products Fadi M. Alkhateeb, B.Sc. Pharm., William R. Doucette, Ph.D.*, Julie M. Ganther-Urmie, Ph.D. Division of Clinical and Administrative Pharmacy, University of Iowa, Iowa City, IA 52246, USA
Abstract Background: Despite the rapid growth in consumer spending on herbal products, we know little about factors that influence such spending. Objective: To use a model of adoption to investigate consumers’ spending on herbal products. Methods: The study used a mail survey of a stratified random sample of 1,300 consumers. The population consisted of consumers aged 18 years and older residing in the United States. The sampling frame was a mailing list purchased from KM Lists. The independent variables were consumer characteristics, social systems, communication channels, and herbal characteristics. The amount of spending on herbs was the dependent measure, with responses divided into monthly spending of $10 or less and more than $10. Binary logistic regression was performed to investigate the association between adoption model variables and spending on herbs. Results: Of the 1,300 mailed surveys, there were 77 undeliverable surveys and 456 usable returned surveys, yielding a usable response rate of 37.3%. A total of 181 (39.7%) respondents reported using herbal products. The logistic regression was performed using the 168 herbal users who reported that they spent money in the past month on herbal products. The overall regression model was significant (P < .05,
* Corresponding author. S518 PHAR, University of Iowa, Iowa City, IA 52246, USA. Tel.: þ1 319 335 8786; fax: þ1 319 353 5646. E-mail address: [email protected] (W.R. Doucette). 1551-7411/$ - see front matter Ó 2006 Elsevier Inc. All rights reserved. doi:10.1016/j.sapharm.2006.03.001
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Nagelkerke R2 ¼ 0.499). The significant influences on spending on herbals were age, over-the-counter (OTC) drug use, and use of an herb professional as an information source about herbs. Older people reported spending more on herbal products than younger people. OTC drug use was positively related to spending on herbals and appears to complement herbal usage. Finally, consumers who obtain information about herbals from an herb professional tend to spend more on herbals. Conclusion: An adoption model may be useful in explaining consumers’ spending on herbal products. Ó 2006 Elsevier Inc. All rights reserved. Keywords: Herbal; Natural product; Cost; Spending
1. Introduction There is an increasing trend in the use of herbal therapies, not only by patients with specific conditions but also in the general population.1,2 Some studies indicate that one third of Americans use herbs.3 In the same way, 2 studies by Eisenberg et al in 1990 and 1997 show that there was a 380% increase in the use of herbal therapies between 1990 and 1997. Sales of herbal products grew to be a $5.1 billion industry in 1997.1,4 Since 1998, the sales have slowed somewhat, although market analysts projected an average annual growth rate of 9.7% through 2004 for the herbal product segment.5 As a result, herbal products have become a multibillion dollar industry in the United States. Despite widespread use, regulation of herbal products is less stringent than that of drugs, requiring less evidence on safety and efficacy. That is, herbs can be marketed without clinical trials that evaluate efficacy and safety. Yet, herbal therapies can interact with each other if taken in combination, with certain foods, and with synthetic prescription and nonprescription drugs.6 The identification of herb-drug and herb-herb interactions has led to heightened awareness of the risks of using herbal therapies. Such interactions can result in discomfort, therapeutic failure of other treatments, and possibly death.6,7 Some herbs (eg, germander, comfrey, and pennyroyal) have well-documented toxic effects.6,8 Finally, contamination during manufacturing and misidentification of plant species are also concerns.9,10 Because of increased expenditures and risks of herb use, it is important to understand the influences on consumer spending for herbal products. Yet, little is known about the factors associated with spending on herbals. No studies have identified factors associated with spending on herbals; however, there has been some study of factors associated with use of herbals. Two studies used the theory of planned behavior to investigate the use of herbals and dietary supplements.11-13 Conner et al reported a significant positive association between intention to use dietary supplements and actual use in
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women.11,12 Bharucha et al reported greater intention to use herbals among Latinos, compared with non-Latinos.13 Another theoretical approach uses an adoption model and posits that herbal use is influenced by characteristics of herbs, consumer variables, as well as communication channels and the consumers’ social system.11 Ritho et al14 identified consumer use of an herbalist and a health food store as positive influences on herbal use. In addition, other studies identified variables associated with consumer herbal usage without obvious use of a theory.7,15-19 These variables will be reviewed in the next section. Because there is likely a positive correlation between using herbal products and spending money on herbals, we expect that an adoption model will explain consumer spending for herbal products. Based on Rogers’ adoption model that was modified by Ritho et al, the model used in this study (see Figure 1) identifies 4 types of influences on a consumer’s spending on herbals: (1) consumer characteristics, (2) social systems, (3) communication channels, and (4) characteristics of herbals.14,20 The objective of this study was to use a model of adoption to investigate consumers’ spending on herbal products. 2. Model of influences on consumer spending 2.1. Consumer characteristics Consumer characteristics refer to demographic and health care attributes. These variables include gender, age, education, medication use, and health insurance coverage. A consistent finding of previous research is that women are more likely than men to use herbals.7,15-18 Also, women have been found
Consumer Characteristics
Social System Spending On Herbals Communication Channels
Herbal Characteristics Fig. 1. Model of influences on spending on herbals.
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to use more nutritional supplements than men.21 The reasons for this finding are not known, though it could be related to differences in attitudes about diet and health.17,22,23 The evidence for age as an influence on herbal use is somewhat equivocal. Some studies have found that older people use more herbals,17,19,21,24 while others have reported greater use among younger people.24,25 Some of the variation could be due to differences in samples, because some of the studies were done on broad populations, while others focused on more narrowly defined groups. Herbal product users have been reported to have completed a higher level of education than nonusers.7,17-19 People with higher education may feel more confident to judge the usefulness of herbals in maintaining their health. Also, people with more education may be exposed to more cues to use herbals, such as advertising and interpersonal influences. Some studies found that OTC drug use is positively related to the use of herbals and appears to complement herbal usage.4,22 In the previous studies about use of herbal products, insurance coverage was not found to be significantly associated with the use of herbal products. However, insurance increasingly covers prescription drugs and lowers out-of-pocket costs for them. This could lead consumers with insurance to use fewer herbals, which do not have costs lowered by insurance. 2.2. Social system A consumer’s social system, defined as a set of interrelated units that are engaged in joint problem solving to accomplish a common goal, may be households, informal groups, or social organizations.20 The social system acts as a boundary within which diffusion and adoption can occur.20 One study reported on the influence of household size and marital status on herbal use.26 That study found that married people and those living in larger households were more likely to use herbals. This could be due to a greater likelihood of someone in the social system (ie, family) being exposed to promotion of herbal products. The social system can also include organizations from which consumers purchase herbal products, such as health food stores. The use of health food stores has been found to be a positive factor in herbal use.14,27 Health food stores attract people to buy herbs through the use of atmosphere and trained staff to serve and promote the different types of herbs to customers. 2.3. Communication channels Communication is the process by which parties create and share information with one another to reach a mutual understanding.20 There are 2 ways for this to happen, through (1) mass media and (2) interpersonal communication channels. Planta et al found that among family medicine clinic patients who used herbs, 66% of the sources of information about herbals
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were interpersonal and 34% of the sources were mass media.28 Mass media include TV or radio, newspapers, and the Internet. Mass media allow one or more people to convey a message about an innovation to a large number of individuals.20 Newspaper is considered a more credible source than other mass media types because people think that newspapers provide less biased information.29 The popularity of herbal products also is readily evident in television advertisements and many Internet sites. Although this lay information regarding herbal medicines often suggests benefits of use, few details are provided regarding important matters such as drug interactions, side effects, or toxicity.29 Interpersonal communication involves face-to-face communication with friends and family, as well as consumer discussions with health care practitioners such as physicians and pharmacists. Communication with friends and family may be considered more effective than communication with health care professionals because friends and family often are easily accessed. Harnack et al found that friends and relatives were the most common source of information about herbals among herbal users in a large city in the Midwest.16 Ritho et al reported that although the use of an herb professional as an information source was not prevalent, it had a significant association with adoption of herbal products.14 This is in contrast to health care practitioners such as physicians and pharmacists, who tend to have limited influence on use of herbs.14 2.4. Characteristics of herbs In this study, we focused on the subjective characteristics of herbs, which include consumer beliefs about the herbal therapies. That is, we asked consumers about their beliefs about herbal products. The logic is that consumers are likely to base their spending on perceptions about products, which may differ from objective characteristics of the products. For example, we asked respondents about their beliefs of the effectiveness and safety of herbal products in general and in comparison with prescription medications in particular. Previous studies indicated that most herb users have more positive perceptions of the safety of herbal products in comparison with prescription drugs.7,30 They also have more favorable attitudes regarding the effectiveness of the herbs to improve health. Conner et al reported that consumers’ beliefs about the outcomes of herbal use were positively related to their intention to use them.12 Similarly, we expected that favorable beliefs about herbals would be associated with spending on herbals.
3. Methods Data were collected from a stratified random sample of 1,300 adults in the United States. The sample was stratified by zip code to ensure adequate
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geographic distribution. The sampling frame was a mailing list purchased from KM Lists. KM Lists is a company that maintains a file containing information on approximately 85% to 90% of US households. The survey was pilot tested by mailing it to a random sample of 100 consumers from the sampling frame. The responses from the pilot test showed that consumers had difficulty answering open-ended questions about their herbal and OTC drug use and spending, so categories were provided for these items in the final version of the survey. Prenotification postcards were mailed 1 week before the survey, and reminder postcards were mailed 1 week after the survey. Business reply envelopes and a $1 incentive also were used to increase the response rate. The survey contained measures of spending on herbal products and each of the modeled influences on spending. Some items had been used in a previous survey of consumers’ herbal use.7 Spending was measured by reporting the approximate amount of money the respondent had spent for herbal products in the last month. Consumer characteristics measured were gender, age, education, number of different OTC medications used in the last month, and presence of health insurance. Four dummy variables were used for education level: graduated high school, some post–high school, graduated from 4 years college, and having a master’s degree, PhD, or professional degree. Less than high school education was the reference category. One social system measure asked respondents whether or not they had purchased herbs from a health food store within the past month. The other social system variable was the number of the people who lived in their household. Communication channels were measured by asking the respondents to identify sources of information about herbal products. These sources included physician or pharmacist, friend or family, herb professional, television/radio, newspaper/magazine, and the Internet. Three subjective characteristics of herbals were assessed: herb safety, effectiveness, and what family and friends thought about herb safety and effectiveness. Respondents used a 5-point Likert scale to rate their agreement with each item: 1 ¼ strongly disagree to 5 ¼ strongly agree. The dependent variable was the amount of money they spent on herbal products in the previous month. We choose this time period because we believed that respondents could recall their spending reliability in such a period, and yet it was long enough to capture some spending. The distribution of the raw data was highly skewed; therefore, the spending variable was recoded into 2 categories: low spenders (not more than $10) and high spenders (greater than $10). Descriptive statistics were calculated for both groups. For respondents reporting spending on herbals in the previous month, binary logistic regression was used to test the model (high spenders vs low spenders), and all independent variables were entered simultaneously. SPSS 12.0 software (SPSS, Chicago, IL) was used for the statistical analyses.
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4. Results Of the 1,300 mailed surveys, there were 77 undeliverable surveys and 456 usable returned surveys, yielding a usable response rate of 37.3%. A total of 181 (39.7%) respondents reported using herbal products, and 168 reported spending on herbs in the past 30 days. The 168 spenders were included in the logistic regression. Descriptive statistics for the variables are shown in Table 1. The mean age of all respondents was just over 52 years. Almost 60% of the low spenders reported having a bachelor’s degree or higher, while only about 35% of the high spenders and all respondents reported that level of education. The proportion of respondents using 5 or more OTC drug products was highest (49.2%) among the high-spender group. High spenders reported the highest level of use of health food stores (68.5%). Friends were the most common source of information about herbs for all groups. The use of an herbal professional as an information source was highest among high spenders (30.1%). The logistic regression was performed using the 168 herbal users who reported they spent money in the last month on herbal products. As shown in Table 2, the overall regression was significant (P < .05), and Nagelkerke R2 ¼ 0.499. Three variables had significant, and positive, influences (P < .05) on spending on herbals: age, OTC drug use, and use of an herb professional as an information source about herbs. People who used an herb professional as an information source about herbs were 5.7 times as likely to be high spenders as those who did not use such an information source.
5. Discussion We found that older herbal users are spending more on herbal products than younger herbal users, which is consistent with some previous studies that reported greater herbal use among older people.17,19,21,26 It could be that herbals tend to be used most frequently for minor health issues.11 As people age, they may encounter more minor health conditions due to age-related changes. This would provide greater opportunity to use herbs. One study reported that older adults were more likely than young adults to agree that herbal products should not be used to treat serious health conditions.30 Also, frequent reasons given for use of herbals included conditions more common in older adults, such as arthritis, memory improvement, and joints.15 Consumers’ self-reported OTC drug use was positively related to spending on herbals and appears to complement herbal usage. These findings are consistent with results reported by both Mantyranata et al9 and Eisenberg et al,4 whereby 20% to 39% of respondents were using prescription or OTC medications along with herbal or homeopathic remedies. It may be that herb users also use OTC drugs because both allow self-treatment by
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F.M. Alkhateeb et al. / Research in Social and Administrative Pharmacy 2 (2006) 254–265 Table 1 Descriptive statistics of model variables by spending on herbals Frequency (%) Consumer characteristics Gender Men Women
All respondents (n ¼ 456)
Low spenders (n ¼ 95)
High spenders (n ¼ 73)
183 (40.1) 273 (59.9)
30 (31.6) 65 (68.4)
37 (50.7) 36 (49.3)
52.04 (16.71)a
44.7 (12.97)a
52.3 (15.87)a
Education Bachelor’s degree or above Less education
165 (36.2) 291 (63.8)
57 (60.0) 38 (40.0)
26 (35.6) 47 (64.4)
OTC drug use (monthly) 1-2 3-4 5-6 7 or more
141 176 66 28
32 39 15 6
5 29 24 9
Insurance Yes No
428 (93.9) 25 (5.5)
90 (94.7) 5 (5.3)
67 (91.8) 6 (8.2)
Social system Health food store Yes
102 (22.4)
46 (48.9)
50 (68.5)
Household size 0-2 3-5 6 and above
263 (57.7) 181 (39.7) 9 (2.0)
47 (49.5) 46 (48.4) 2 (2.1)
42 (57.5) 29 (39.7) 2 (2.7)
Communication channel Physician or pharmacist Friend or family Herb professional TV/radio Newspaper/magazine Internet
74 139 34 79 90 66
29 53 9 26 32 26
24 45 22 27 32 23
Herbal characteristics Herb vs prescription safety Herbs improve health Family/friends herb safe
2.63 (0.95)b 3.05 (0.89)b 3.06 (0.86)b
Age (y)
a b
(34.3) (42.8) (16.1) (6.8)
(16.2) (30.5) (7.5) (17.3) (19.7) (14.5)
(34.8) (42.4) (16.3) (6.5)
(30.5) (55.8) (9.5) (27.4) (33.7) (27.4)
2.60 (0.87)b 3.33 (0.74)b 3.17 (0.82)b
(7.5) (43.3) (35.8) (13.4)
(32.9) (61.6) (30.1) (37.0) (43.8) (31.5)
3.25 (1.16)b 3.84 (0.87)b 3.61 (0.76)b
Mean response (SD). Mean scale response (SD) scale: 1 ¼ strongly disagree; 5 ¼ strongly agree.
the consumer. Future research is needed to more closely investigate the relationship between OTC drug use and herbal use. For example, consumers could be studied to better determine when they would consider herbal products to be substitutes for drugs, either OTC or prescription. The use of an herb professional was positively associated with spending on herbals. While this may be a positive situation, it is difficult to know
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Table 2 Logistic regression of spending on herbal products Variable
b
SE (b)
Odds ratio (eb)
Significance
Consumer characteristics Hschgrada Somecollegea Collegegrada Collegeplusa Health insurance OTC drug useb Gender Age
0.820 1.199 2.090 2.102 1.106 0.805 0.764 0.039
1.150 1.111 1.177 1.238 0.697 0.248 0.450 0.018
0.921 0.302 0.124 0.122 0.331 2.236 2.147 1.040
0.943 0.281 0.076 0.090 0.113 0.001** 0.090 0.034*
Social system Food store Household
0.527 0.240
0.452 0.189
1.694 0.787
0.244 0.205
Communication channels Doctor or pharmacist Friends or family Herb professional TV or radio Newspaper or magazine Internet
0.270 0.291 1.740 0.557 0.156 0.766
0.481 0.515 0.614 0.578 0.542 0.528
0.763 1.338 5.700 0.573 0.855 2.151
0.574 0.572 0.005** 0.335 0.773 0.147
0.370 0.359 0.449
0.268 0.381 0.296
1.447 1.432 1.567
0.168 0.346 0.129
5.784
2.091
0.003
0.006**
Herbal characteristics Herbs are safer than prescription drugsc I feel that herbs improve healthc My family and friends think that herbs are safe and effectivec Constant
The dependent variable was low spenders ¼ 0 (spent no more than $10 on herbals in past month) vs high spenders ¼ 1 (spent more than $10 on herbals in past month). **Significant at P .01, *significant at P .05, n ¼ 168, Nagelkerke R2 ¼ 0.499. a These are the dummy variables of the education level: Graduated high school (hschgrad), some post–high school (somecollege), graduated 4 years college (collegegrad), and master’s, PhD, or professional degree (collegeplus). The reference group was elementary school or some high school. b The number of OTCs used in the past month had 5 categories: 0 ¼ none, 1 ¼ 1-2, 2 ¼ 3-4, 3 ¼ 5-6, 4 ¼ 7 or more. c These were measured by a Likert scale (1 ¼ strongly disagree to 5 ¼ strongly agree).
for sure since qualifications of herbalists are not uniform. The United States does not have regulations or guidelines for herbal practice or national standards for herbal education.31 There are times when a health care provider working with a patient who is taking herbal products could use the assistance and advice from a medical herbalist who can evaluate the herbal products that the patient is taking. Libster reviewed approaches used by practitioners to evaluate the expertise of a medical herbalist.31 She suggested that practitioners consider the herbalist’s education, experience, intuition to understand a patient’s situation, and clinical judgment. This would allow
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evaluation of the herbalist’s assessment approach, knowledge of herbs, and treatment planning process. It would be informative to learn about how the herbalist puts together collected information and makes clinical decisions. Pharmacists and physicians seeking an herbalist’s expertise could ask him or her to describe his or her approach to managing a patient. In a previous study of consumers’ use of herbals, Ritho et al reported that use of an herb professional as an information source about herbs was positively associated with use of herbals.14 The consistent findings draw attention to the role of herb professionals in guiding the use of herbals. This raises some questions for future study. For example, what are the characteristics of consumers who use herbalists? Do herbalists recommend herbs that they sell themselves? What processes are used by consumers in identifying and selecting an herbal professional? It is possible that theories used to study consumers’ use of health care professionals (eg, physicians) could be used to study their use of herbalist services. Further work is needed to improve our study of consumers’ use of herb professionals as information sources about herbs. We found that herbal characteristics (beliefs) were not associated significantly with the spending of money on herbs. Although herb users held positive views of herbals, these beliefs were not sufficient to differentiate spending on herbs. Perhaps the herb users generally hold positive beliefs about herbs, regardless of how much they spend on them. Thus, the beliefs about herbs did not explain consumer spending on herbs. Although this model was useful in predicting the consumer spending on herbal products, there were some limitations to our study. One was that data in this study were self-reported and thus dependent on respondents’ veracity and recall. Consumer difficulty with recall may have increased measurement error. Another limitation is that information could not be obtained from nonrespondents; so nonresponse bias is possible. However, surveys are used regularly to collect similar information from consumers. Finally, it is possible that the consumers included in KM lists differ in some way from the general population, which limits the generalizability of these findings. 6. Conclusion An adoption model can help explain consumers’ spending on herbal products. In our sample, older people reported spending more on herbal products than younger people. OTC drug use was positively related to spending on herbals and appears to complement herbal usage. Finally, consumers who obtain information about herbals from an herb professional tend to spend more on herbals. Acknowledgment This study was funded by a new investigator grant from the American Association of Colleges of Pharmacy, Alexandria, VA.
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25. Trotter RT. Remedios caseros: Mexican American home remedies and community health problems. Soc Sci Med. 1981;15B:107–114. 26. Brown JS, Marcy SA. The use of botanicals for health purposes by members of a prepaid health plan. Res Nurs Health. 1991;14:339–350. 27. Martin KJ, Jordan TR, Vassar AD, White DB. Herbal and nonherbal alternative medicine use in northwest Ohio. Ann Pharmacother. 2002;36:1862–1869. 28. Planta M, Gunderson B, Petitt JC. Prevalence of the use of herbal products in a low-income population. Fam Med. 2000;32:252–257. 29. Bouldin AS, Smith MC, Banahan BF, et al. Herbal supplement information and the consumer. Drug Inf J. 2000;34:1339–1353. 30. Harnack LJ, DeRosier KL, Rydell SA. Results of a population-based survey of adults’ attitudes and beliefs about herbal products. J Am Pharm Assoc. 2003;43:596–601. 31. Libster M. Guidelines for selecting a medical herbalist for consultation and referral: consulting a medical herbalist. J Altern Complement Med. 1999;5:457–462.
Original research
Influences on consumer spending for herbal products Fadi M. Alkhateeb, B.Sc. Pharm., William R. Doucette, Ph.D.*, Julie M. Ganther-Urmie, Ph.D. Division of Clinical and Administrative Pharmacy, University of Iowa, Iowa City, IA 52246, USA
Abstract Background: Despite the rapid growth in consumer spending on herbal products, we know little about factors that influence such spending. Objective: To use a model of adoption to investigate consumers’ spending on herbal products. Methods: The study used a mail survey of a stratified random sample of 1,300 consumers. The population consisted of consumers aged 18 years and older residing in the United States. The sampling frame was a mailing list purchased from KM Lists. The independent variables were consumer characteristics, social systems, communication channels, and herbal characteristics. The amount of spending on herbs was the dependent measure, with responses divided into monthly spending of $10 or less and more than $10. Binary logistic regression was performed to investigate the association between adoption model variables and spending on herbs. Results: Of the 1,300 mailed surveys, there were 77 undeliverable surveys and 456 usable returned surveys, yielding a usable response rate of 37.3%. A total of 181 (39.7%) respondents reported using herbal products. The logistic regression was performed using the 168 herbal users who reported that they spent money in the past month on herbal products. The overall regression model was significant (P < .05,
* Corresponding author. S518 PHAR, University of Iowa, Iowa City, IA 52246, USA. Tel.: þ1 319 335 8786; fax: þ1 319 353 5646. E-mail address: [email protected] (W.R. Doucette). 1551-7411/$ - see front matter Ó 2006 Elsevier Inc. All rights reserved. doi:10.1016/j.sapharm.2006.03.001
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Nagelkerke R2 ¼ 0.499). The significant influences on spending on herbals were age, over-the-counter (OTC) drug use, and use of an herb professional as an information source about herbs. Older people reported spending more on herbal products than younger people. OTC drug use was positively related to spending on herbals and appears to complement herbal usage. Finally, consumers who obtain information about herbals from an herb professional tend to spend more on herbals. Conclusion: An adoption model may be useful in explaining consumers’ spending on herbal products. Ó 2006 Elsevier Inc. All rights reserved. Keywords: Herbal; Natural product; Cost; Spending
1. Introduction There is an increasing trend in the use of herbal therapies, not only by patients with specific conditions but also in the general population.1,2 Some studies indicate that one third of Americans use herbs.3 In the same way, 2 studies by Eisenberg et al in 1990 and 1997 show that there was a 380% increase in the use of herbal therapies between 1990 and 1997. Sales of herbal products grew to be a $5.1 billion industry in 1997.1,4 Since 1998, the sales have slowed somewhat, although market analysts projected an average annual growth rate of 9.7% through 2004 for the herbal product segment.5 As a result, herbal products have become a multibillion dollar industry in the United States. Despite widespread use, regulation of herbal products is less stringent than that of drugs, requiring less evidence on safety and efficacy. That is, herbs can be marketed without clinical trials that evaluate efficacy and safety. Yet, herbal therapies can interact with each other if taken in combination, with certain foods, and with synthetic prescription and nonprescription drugs.6 The identification of herb-drug and herb-herb interactions has led to heightened awareness of the risks of using herbal therapies. Such interactions can result in discomfort, therapeutic failure of other treatments, and possibly death.6,7 Some herbs (eg, germander, comfrey, and pennyroyal) have well-documented toxic effects.6,8 Finally, contamination during manufacturing and misidentification of plant species are also concerns.9,10 Because of increased expenditures and risks of herb use, it is important to understand the influences on consumer spending for herbal products. Yet, little is known about the factors associated with spending on herbals. No studies have identified factors associated with spending on herbals; however, there has been some study of factors associated with use of herbals. Two studies used the theory of planned behavior to investigate the use of herbals and dietary supplements.11-13 Conner et al reported a significant positive association between intention to use dietary supplements and actual use in
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women.11,12 Bharucha et al reported greater intention to use herbals among Latinos, compared with non-Latinos.13 Another theoretical approach uses an adoption model and posits that herbal use is influenced by characteristics of herbs, consumer variables, as well as communication channels and the consumers’ social system.11 Ritho et al14 identified consumer use of an herbalist and a health food store as positive influences on herbal use. In addition, other studies identified variables associated with consumer herbal usage without obvious use of a theory.7,15-19 These variables will be reviewed in the next section. Because there is likely a positive correlation between using herbal products and spending money on herbals, we expect that an adoption model will explain consumer spending for herbal products. Based on Rogers’ adoption model that was modified by Ritho et al, the model used in this study (see Figure 1) identifies 4 types of influences on a consumer’s spending on herbals: (1) consumer characteristics, (2) social systems, (3) communication channels, and (4) characteristics of herbals.14,20 The objective of this study was to use a model of adoption to investigate consumers’ spending on herbal products. 2. Model of influences on consumer spending 2.1. Consumer characteristics Consumer characteristics refer to demographic and health care attributes. These variables include gender, age, education, medication use, and health insurance coverage. A consistent finding of previous research is that women are more likely than men to use herbals.7,15-18 Also, women have been found
Consumer Characteristics
Social System Spending On Herbals Communication Channels
Herbal Characteristics Fig. 1. Model of influences on spending on herbals.
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to use more nutritional supplements than men.21 The reasons for this finding are not known, though it could be related to differences in attitudes about diet and health.17,22,23 The evidence for age as an influence on herbal use is somewhat equivocal. Some studies have found that older people use more herbals,17,19,21,24 while others have reported greater use among younger people.24,25 Some of the variation could be due to differences in samples, because some of the studies were done on broad populations, while others focused on more narrowly defined groups. Herbal product users have been reported to have completed a higher level of education than nonusers.7,17-19 People with higher education may feel more confident to judge the usefulness of herbals in maintaining their health. Also, people with more education may be exposed to more cues to use herbals, such as advertising and interpersonal influences. Some studies found that OTC drug use is positively related to the use of herbals and appears to complement herbal usage.4,22 In the previous studies about use of herbal products, insurance coverage was not found to be significantly associated with the use of herbal products. However, insurance increasingly covers prescription drugs and lowers out-of-pocket costs for them. This could lead consumers with insurance to use fewer herbals, which do not have costs lowered by insurance. 2.2. Social system A consumer’s social system, defined as a set of interrelated units that are engaged in joint problem solving to accomplish a common goal, may be households, informal groups, or social organizations.20 The social system acts as a boundary within which diffusion and adoption can occur.20 One study reported on the influence of household size and marital status on herbal use.26 That study found that married people and those living in larger households were more likely to use herbals. This could be due to a greater likelihood of someone in the social system (ie, family) being exposed to promotion of herbal products. The social system can also include organizations from which consumers purchase herbal products, such as health food stores. The use of health food stores has been found to be a positive factor in herbal use.14,27 Health food stores attract people to buy herbs through the use of atmosphere and trained staff to serve and promote the different types of herbs to customers. 2.3. Communication channels Communication is the process by which parties create and share information with one another to reach a mutual understanding.20 There are 2 ways for this to happen, through (1) mass media and (2) interpersonal communication channels. Planta et al found that among family medicine clinic patients who used herbs, 66% of the sources of information about herbals
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were interpersonal and 34% of the sources were mass media.28 Mass media include TV or radio, newspapers, and the Internet. Mass media allow one or more people to convey a message about an innovation to a large number of individuals.20 Newspaper is considered a more credible source than other mass media types because people think that newspapers provide less biased information.29 The popularity of herbal products also is readily evident in television advertisements and many Internet sites. Although this lay information regarding herbal medicines often suggests benefits of use, few details are provided regarding important matters such as drug interactions, side effects, or toxicity.29 Interpersonal communication involves face-to-face communication with friends and family, as well as consumer discussions with health care practitioners such as physicians and pharmacists. Communication with friends and family may be considered more effective than communication with health care professionals because friends and family often are easily accessed. Harnack et al found that friends and relatives were the most common source of information about herbals among herbal users in a large city in the Midwest.16 Ritho et al reported that although the use of an herb professional as an information source was not prevalent, it had a significant association with adoption of herbal products.14 This is in contrast to health care practitioners such as physicians and pharmacists, who tend to have limited influence on use of herbs.14 2.4. Characteristics of herbs In this study, we focused on the subjective characteristics of herbs, which include consumer beliefs about the herbal therapies. That is, we asked consumers about their beliefs about herbal products. The logic is that consumers are likely to base their spending on perceptions about products, which may differ from objective characteristics of the products. For example, we asked respondents about their beliefs of the effectiveness and safety of herbal products in general and in comparison with prescription medications in particular. Previous studies indicated that most herb users have more positive perceptions of the safety of herbal products in comparison with prescription drugs.7,30 They also have more favorable attitudes regarding the effectiveness of the herbs to improve health. Conner et al reported that consumers’ beliefs about the outcomes of herbal use were positively related to their intention to use them.12 Similarly, we expected that favorable beliefs about herbals would be associated with spending on herbals.
3. Methods Data were collected from a stratified random sample of 1,300 adults in the United States. The sample was stratified by zip code to ensure adequate
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geographic distribution. The sampling frame was a mailing list purchased from KM Lists. KM Lists is a company that maintains a file containing information on approximately 85% to 90% of US households. The survey was pilot tested by mailing it to a random sample of 100 consumers from the sampling frame. The responses from the pilot test showed that consumers had difficulty answering open-ended questions about their herbal and OTC drug use and spending, so categories were provided for these items in the final version of the survey. Prenotification postcards were mailed 1 week before the survey, and reminder postcards were mailed 1 week after the survey. Business reply envelopes and a $1 incentive also were used to increase the response rate. The survey contained measures of spending on herbal products and each of the modeled influences on spending. Some items had been used in a previous survey of consumers’ herbal use.7 Spending was measured by reporting the approximate amount of money the respondent had spent for herbal products in the last month. Consumer characteristics measured were gender, age, education, number of different OTC medications used in the last month, and presence of health insurance. Four dummy variables were used for education level: graduated high school, some post–high school, graduated from 4 years college, and having a master’s degree, PhD, or professional degree. Less than high school education was the reference category. One social system measure asked respondents whether or not they had purchased herbs from a health food store within the past month. The other social system variable was the number of the people who lived in their household. Communication channels were measured by asking the respondents to identify sources of information about herbal products. These sources included physician or pharmacist, friend or family, herb professional, television/radio, newspaper/magazine, and the Internet. Three subjective characteristics of herbals were assessed: herb safety, effectiveness, and what family and friends thought about herb safety and effectiveness. Respondents used a 5-point Likert scale to rate their agreement with each item: 1 ¼ strongly disagree to 5 ¼ strongly agree. The dependent variable was the amount of money they spent on herbal products in the previous month. We choose this time period because we believed that respondents could recall their spending reliability in such a period, and yet it was long enough to capture some spending. The distribution of the raw data was highly skewed; therefore, the spending variable was recoded into 2 categories: low spenders (not more than $10) and high spenders (greater than $10). Descriptive statistics were calculated for both groups. For respondents reporting spending on herbals in the previous month, binary logistic regression was used to test the model (high spenders vs low spenders), and all independent variables were entered simultaneously. SPSS 12.0 software (SPSS, Chicago, IL) was used for the statistical analyses.
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4. Results Of the 1,300 mailed surveys, there were 77 undeliverable surveys and 456 usable returned surveys, yielding a usable response rate of 37.3%. A total of 181 (39.7%) respondents reported using herbal products, and 168 reported spending on herbs in the past 30 days. The 168 spenders were included in the logistic regression. Descriptive statistics for the variables are shown in Table 1. The mean age of all respondents was just over 52 years. Almost 60% of the low spenders reported having a bachelor’s degree or higher, while only about 35% of the high spenders and all respondents reported that level of education. The proportion of respondents using 5 or more OTC drug products was highest (49.2%) among the high-spender group. High spenders reported the highest level of use of health food stores (68.5%). Friends were the most common source of information about herbs for all groups. The use of an herbal professional as an information source was highest among high spenders (30.1%). The logistic regression was performed using the 168 herbal users who reported they spent money in the last month on herbal products. As shown in Table 2, the overall regression was significant (P < .05), and Nagelkerke R2 ¼ 0.499. Three variables had significant, and positive, influences (P < .05) on spending on herbals: age, OTC drug use, and use of an herb professional as an information source about herbs. People who used an herb professional as an information source about herbs were 5.7 times as likely to be high spenders as those who did not use such an information source.
5. Discussion We found that older herbal users are spending more on herbal products than younger herbal users, which is consistent with some previous studies that reported greater herbal use among older people.17,19,21,26 It could be that herbals tend to be used most frequently for minor health issues.11 As people age, they may encounter more minor health conditions due to age-related changes. This would provide greater opportunity to use herbs. One study reported that older adults were more likely than young adults to agree that herbal products should not be used to treat serious health conditions.30 Also, frequent reasons given for use of herbals included conditions more common in older adults, such as arthritis, memory improvement, and joints.15 Consumers’ self-reported OTC drug use was positively related to spending on herbals and appears to complement herbal usage. These findings are consistent with results reported by both Mantyranata et al9 and Eisenberg et al,4 whereby 20% to 39% of respondents were using prescription or OTC medications along with herbal or homeopathic remedies. It may be that herb users also use OTC drugs because both allow self-treatment by
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F.M. Alkhateeb et al. / Research in Social and Administrative Pharmacy 2 (2006) 254–265 Table 1 Descriptive statistics of model variables by spending on herbals Frequency (%) Consumer characteristics Gender Men Women
All respondents (n ¼ 456)
Low spenders (n ¼ 95)
High spenders (n ¼ 73)
183 (40.1) 273 (59.9)
30 (31.6) 65 (68.4)
37 (50.7) 36 (49.3)
52.04 (16.71)a
44.7 (12.97)a
52.3 (15.87)a
Education Bachelor’s degree or above Less education
165 (36.2) 291 (63.8)
57 (60.0) 38 (40.0)
26 (35.6) 47 (64.4)
OTC drug use (monthly) 1-2 3-4 5-6 7 or more
141 176 66 28
32 39 15 6
5 29 24 9
Insurance Yes No
428 (93.9) 25 (5.5)
90 (94.7) 5 (5.3)
67 (91.8) 6 (8.2)
Social system Health food store Yes
102 (22.4)
46 (48.9)
50 (68.5)
Household size 0-2 3-5 6 and above
263 (57.7) 181 (39.7) 9 (2.0)
47 (49.5) 46 (48.4) 2 (2.1)
42 (57.5) 29 (39.7) 2 (2.7)
Communication channel Physician or pharmacist Friend or family Herb professional TV/radio Newspaper/magazine Internet
74 139 34 79 90 66
29 53 9 26 32 26
24 45 22 27 32 23
Herbal characteristics Herb vs prescription safety Herbs improve health Family/friends herb safe
2.63 (0.95)b 3.05 (0.89)b 3.06 (0.86)b
Age (y)
a b
(34.3) (42.8) (16.1) (6.8)
(16.2) (30.5) (7.5) (17.3) (19.7) (14.5)
(34.8) (42.4) (16.3) (6.5)
(30.5) (55.8) (9.5) (27.4) (33.7) (27.4)
2.60 (0.87)b 3.33 (0.74)b 3.17 (0.82)b
(7.5) (43.3) (35.8) (13.4)
(32.9) (61.6) (30.1) (37.0) (43.8) (31.5)
3.25 (1.16)b 3.84 (0.87)b 3.61 (0.76)b
Mean response (SD). Mean scale response (SD) scale: 1 ¼ strongly disagree; 5 ¼ strongly agree.
the consumer. Future research is needed to more closely investigate the relationship between OTC drug use and herbal use. For example, consumers could be studied to better determine when they would consider herbal products to be substitutes for drugs, either OTC or prescription. The use of an herb professional was positively associated with spending on herbals. While this may be a positive situation, it is difficult to know
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Table 2 Logistic regression of spending on herbal products Variable
b
SE (b)
Odds ratio (eb)
Significance
Consumer characteristics Hschgrada Somecollegea Collegegrada Collegeplusa Health insurance OTC drug useb Gender Age
0.820 1.199 2.090 2.102 1.106 0.805 0.764 0.039
1.150 1.111 1.177 1.238 0.697 0.248 0.450 0.018
0.921 0.302 0.124 0.122 0.331 2.236 2.147 1.040
0.943 0.281 0.076 0.090 0.113 0.001** 0.090 0.034*
Social system Food store Household
0.527 0.240
0.452 0.189
1.694 0.787
0.244 0.205
Communication channels Doctor or pharmacist Friends or family Herb professional TV or radio Newspaper or magazine Internet
0.270 0.291 1.740 0.557 0.156 0.766
0.481 0.515 0.614 0.578 0.542 0.528
0.763 1.338 5.700 0.573 0.855 2.151
0.574 0.572 0.005** 0.335 0.773 0.147
0.370 0.359 0.449
0.268 0.381 0.296
1.447 1.432 1.567
0.168 0.346 0.129
5.784
2.091
0.003
0.006**
Herbal characteristics Herbs are safer than prescription drugsc I feel that herbs improve healthc My family and friends think that herbs are safe and effectivec Constant
The dependent variable was low spenders ¼ 0 (spent no more than $10 on herbals in past month) vs high spenders ¼ 1 (spent more than $10 on herbals in past month). **Significant at P .01, *significant at P .05, n ¼ 168, Nagelkerke R2 ¼ 0.499. a These are the dummy variables of the education level: Graduated high school (hschgrad), some post–high school (somecollege), graduated 4 years college (collegegrad), and master’s, PhD, or professional degree (collegeplus). The reference group was elementary school or some high school. b The number of OTCs used in the past month had 5 categories: 0 ¼ none, 1 ¼ 1-2, 2 ¼ 3-4, 3 ¼ 5-6, 4 ¼ 7 or more. c These were measured by a Likert scale (1 ¼ strongly disagree to 5 ¼ strongly agree).
for sure since qualifications of herbalists are not uniform. The United States does not have regulations or guidelines for herbal practice or national standards for herbal education.31 There are times when a health care provider working with a patient who is taking herbal products could use the assistance and advice from a medical herbalist who can evaluate the herbal products that the patient is taking. Libster reviewed approaches used by practitioners to evaluate the expertise of a medical herbalist.31 She suggested that practitioners consider the herbalist’s education, experience, intuition to understand a patient’s situation, and clinical judgment. This would allow
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evaluation of the herbalist’s assessment approach, knowledge of herbs, and treatment planning process. It would be informative to learn about how the herbalist puts together collected information and makes clinical decisions. Pharmacists and physicians seeking an herbalist’s expertise could ask him or her to describe his or her approach to managing a patient. In a previous study of consumers’ use of herbals, Ritho et al reported that use of an herb professional as an information source about herbs was positively associated with use of herbals.14 The consistent findings draw attention to the role of herb professionals in guiding the use of herbals. This raises some questions for future study. For example, what are the characteristics of consumers who use herbalists? Do herbalists recommend herbs that they sell themselves? What processes are used by consumers in identifying and selecting an herbal professional? It is possible that theories used to study consumers’ use of health care professionals (eg, physicians) could be used to study their use of herbalist services. Further work is needed to improve our study of consumers’ use of herb professionals as information sources about herbs. We found that herbal characteristics (beliefs) were not associated significantly with the spending of money on herbs. Although herb users held positive views of herbals, these beliefs were not sufficient to differentiate spending on herbs. Perhaps the herb users generally hold positive beliefs about herbs, regardless of how much they spend on them. Thus, the beliefs about herbs did not explain consumer spending on herbs. Although this model was useful in predicting the consumer spending on herbal products, there were some limitations to our study. One was that data in this study were self-reported and thus dependent on respondents’ veracity and recall. Consumer difficulty with recall may have increased measurement error. Another limitation is that information could not be obtained from nonrespondents; so nonresponse bias is possible. However, surveys are used regularly to collect similar information from consumers. Finally, it is possible that the consumers included in KM lists differ in some way from the general population, which limits the generalizability of these findings. 6. Conclusion An adoption model can help explain consumers’ spending on herbal products. In our sample, older people reported spending more on herbal products than younger people. OTC drug use was positively related to spending on herbals and appears to complement herbal usage. Finally, consumers who obtain information about herbals from an herb professional tend to spend more on herbals. Acknowledgment This study was funded by a new investigator grant from the American Association of Colleges of Pharmacy, Alexandria, VA.
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