Only one in three adults reported disclosing their use of HDS to their conventional health care provider. Importantly, we found that only 39% of prescription medication users and only 44% of adults with two or more chronic medical conditions reported disclosing their HDS use to their health care provider. For most chronic medical conditions, fewer than 1 of 2 HDS users reported its use to their health care provider. Even after adjustment,*
individuals who reported having vascular, pulmonary, or endocrine conditions were no more likely to report HDS use to their conventional health care provider than individuals without these conditions.
This study expands on previously reported rates of disclosure of HDS to conventional health care providers in the United States.18,19
Our findings are consistent with studies in other countries that indicate few HDS users disclose HDS use to their conventional health care provider. One study of British adults also reported a HDS disclosure rate of 33%.20
Clement et al. studied HDS users accessing primary health care in an ethnically diverse population in Trinidad.21
Despite 87% of individuals perceiving herbal remedies as efficacious, less than 25% informed their physician about use. A Malaysian study found that less than 10% of herbal therapy users disclosed use to their physician.22
We found significant ethnic variations in HDS disclosure rates, with Hispanic and Asian Americans being much less likely to disclose their HDS use. These findings support community-based surveys that found Hispanic and Asian Americans had low rates of HDS disclosure (21% to 31%).23,24
We suspect that more vulnerable members of these communities, including those with limited English proficiency or recent immigrants, may be even less likely to discuss HDS use with their physicians.11
This is further supported by our finding that individuals who were less educated and did not have a regular source of conventional health care were substantially less likely to disclose HDS use.
Do patients feel comfortable discussing their HDS use with their conventional health care provider? In studies of Asian Americans25
and Hispanic Americans,26
it was postulated that individuals do not engage in discussions of CAM out of fear of negative reactions from their conventional health care providers. However, when these discussions do take place, patients report improved quality of care.27
Our data do not provide information on who initiates the discussion about HDS use, or patients' comfort with such discussions. Are physicians asking their patients about their use of HDS? In a study of perimenopausal women, only 40% reported that their physicians had ever asked about HDS use.28
A study of Hispanic Americans found that only 26% reported that their doctors asked them about use of herbs.29
Combined, these studies suggest that physicians infrequently ask their patients about the use of HDS.
Respondents who used glucosamine/chondroitin had higher rates of HDS disclosure. We speculate several reasons as to why this may be the case. Glucosamine/chondroitin is most often used in the treatment of osteoarthritis. In recent years, there have been large double-blind, randomized controlled trials and meta-analyses that have raised awareness about its efficacy and use.30,31
Given known risks associated with conventional treatments of osteoarthritis, many patients may have opted to use glucosamine/chondroitin in consultation with their physician. However, despite these facts, only 1 in 2 respondents who used glucosamine/chondroitin reported HDS disclosure.
Our study has several important limitations. First, as mentioned in previous studies,10,11
many of the 35 HDS that were asked about in the survey are marketed primarily to the non-Hispanic white population. Since surveys are conducted in English and Spanish only, group who do not speak English or Spanish were not captured in the sample, without relying on English-speaking or Spanish-speaking household members to assist in translating questions during the interview.32
These factors may not only underestimate the prevalence of HDS use among specific populations, such as Asian Americans, but may also underestimate the rate of HDS disclosure to conventional health care providers. Secondly, we were not able to assess disclosure rates for specific HDS, as the NHIS did not assess whether respondents disclosed use of the specific HDS (e.g., glucosamine/chondroitin). Since we assumed that disclosure of HDS use included all HDS that a respondent was using and since nearly 60% of respondents had used more than one herb,33
our reported disclosure rates may overestimate the true disclosure rate. Future NHIS instruments might ask about specific HDS disclosure, thereby increasing statistical power to study important health care information about patient-physician communication, especially with regard to particular HDS that have known significant herb-drug interactions (e.g., St. John's wort). Finally, although we found that respondents who visited a clinic more often were more likely to disclose use of HDS, the NHIS does not provide any information about the physicians to whom respondents disclosed use of HDS. Greater physician and patient language concordance is associated with higher patient ratings on interpersonal processes of care, specifically elicitation and responsiveness.34
Hence, future survey instruments might query respondents about physician characteristics.
While our study is a cross-sectional analysis representative of the national population, our findings have important implications. Low rates of HDS disclosure by individuals with chronic medical conditions should raise concern for herb-drug interactions, side effects, and safety of dietary supplements; this should compel physicians to ask their patients about their use of HDS, especially patients with multiple comorbid conditions who are on prescription medications.
Given our findings that Hispanic and Asian Americans have lower HDS disclosure rates, we suspect that this may, in part, reflect providers' lack of training in effective crosscultural care. In conjunction with findings from other studies, the education of conventional health care providers must include curricula on HDS, so they may provide care that is both clinically and culturally competent. In the 2003 Institute of Medicine (IOM) report on racial and ethnic disparities, the Committee found that patient-doctor communication is directly linked to patient satisfaction and health outcomes.35
Cross-cultural education should provide a tool to help reduce health care disparities. Hence, in concert with this IOM statement, there must exist an imperative within medical education to teach future providers how to ask patients about their use of HDS. Recent work that has emphasized residents' preparedness to provide cross-cultural care is augmented by the establishment of formal education in their curriculum.36
In light of our findings, we suggest that the HDS education be included as a part of cross-cultural education, and that HDS disclosure rates can be used as a measurable outcome for studying racial and ethnic disparities in health care.
Future research should examine HDS use and its relation to patient belief systems and the extent to which these supplements are being used in conjunction with or substitution for conditions for which conventional therapies are effective. Studies should also begin to examine mechanisms by which health care providers elicit information from their patients so they may provide appropriate patient-centered medical care.