© The Author(s) 2023
Article reuse guidelines: sagepub.com/journals-permissionsDOI: 10.1177/17151635231152243
The widespread marketing of natural health products affects how our patients choose to spend their money. This study explored the impact that these products can have medically for patients on intensive cardiac medication regimens. Do you know what natural health products your patients are using?
La commercialisation à grande échelle des produits de santé naturels a une incidence sur la façon dont nos patients choisissent de dépenser leur argent. Cette étude a exploré les incidences que ces produits peuvent avoir sur le plan médical pour les patients qui suivent un régime posologique complexe pour le traitement de troubles cardiaques. Savez-vous quels produits de santé naturels vos patients utilisent?
Background: Natural health product (NHP) use is common among Canadians, but the NHPs used by outpatients with cardiovascular conditions such as atrial fibrillation and heart failure have not been identified.
Objectives: Describe NHP use among outpatient cardiac patients, assess drug interactions and their potential implications and determine NHP documentation by health care providers.
Methods: Telephone interviews were conducted by the main researcher with patients who attended the Cardiac Clinics at the Royal Columbian Hospital. Medication reconciliation was performed to elicit information regarding NHP use and clinic charts were used to supplement demographic information.
Results: There were 119 successful interviews. Most patients were approximately 65 years old and male, were diagnosed with atrial fibrillation, had 2 to 3 queried comorbidities and took 2 cardiovascular medications. It was found that 62% of patients use NHPs, and 239 individual NHPs were identified. The most common NHPs used were vitamins and minerals (63%), especially vitamin D (13%), multivitamins (8%) and omega-3s (8%). Interactions between cardiac medications and NHPs occurred in 86% of patients. NHP use was completely documented by health care providers in 24% of patients.
Conclusion: NHP use is common among patients who attend outpatient cardiac clinics. Interactions between NHPs and cardiovascular medications are prevalent and may carry specific individual patient risks. NHP documentation by health care providers is often incomplete. Can Pharm J (Ott) 2023;156:94-101.
Natural health products (NHPs) are defined as naturally occurring substances that are purported to restore or maintain good health. Since 2004, the Natural and Non-prescription Health Products Directorate (NNHPD), a regulatory body under Health Canada, has been responsible for the oversight of NHPs. As defined by the NNHPD, NHPs include vitamins and minerals, herbal remedies, homeopathic medicines, traditional medicines such as Chinese medicines, probiotics and other products like amino acids and essential fatty acids.1 The goal of NNHPD is to ensure that NHPs are safe, effective and of high quality. In a 2005 survey, 71% of Canadians had reported use of NHPs.2
NHPs that have been licensed for sale in Canada display a labelled Natural Product Number or Homeopathic Medicine Number. NNHDP regulates that NHPs’ ingredients (medical and nonmedical), source, dose, potency and recommended use(s) are documented for public safety.3 Additionally, the licensee must provide evidence and safety information about their product, demonstrate good manufacturing processes and be prepared to monitor for adverse reactions, similar to the process for prescription medications.3 Despite the NNHPD’s efforts to ensure the safety of NHPs, these products are not subject to the same rigorous scientific testing as prescription products, and therefore, minimal information is known regarding NHPs’ efficacy, safety and cost-effectiveness. NHPs may cause adverse effects or interact with prescription medications. In fact, 12% of Canadians who use NHPs reported that they have experienced an adverse reaction from them.1 Patients with cardiovascular conditions, such as heart failure, atrial fibrillation and other conditions affecting the heart, are at increased risk for adverse effects from NHP and drug interactions, as these patients often take numerous medications. The American Heart Association does not recommend NHP use in patients with cardiovascular conditions due to a lack of evidence available for NHPs.4
Two studies have evaluated the use of NHPs in patients with cardiac conditions. A 2009 American study by Albert et al.5 on outpatient heart failure patients found that over-thecounter (OTC) herbal and drug use was extremely prevalent. While use of herbals, such as echinacea, cranberry and garlic, was uncommon at 12%, OTC drug use, which by the study definition included vitamins and minerals, was high at 94%.5 A Canadian study of inpatient cardiovascular patients was conducted to determine NHP use and the accuracy of best possible medication history (BPMH) completed by health care providers. This study showed that 78% of patients used NHPs.6 Given the prevalent NHP use in these studies, the implications of NHP use among the target population of outpatient patients with cardiac conditions warrant further investigation.
Documentation of NHPs during a medication history assessment is an integral component to properly assess for potential interactions. Nearly 70% of patients who use NHPs do not discuss them with their clinicians. This may result in unmonitored use and a high potential for drug interactions and other adverse events.7,8 The objectives of this study are to describe the pattern and frequency of NHP use, analyze the potential for drug interactions and assess the accuracy of NHP documentation by health care providers at an outpatient cardiac clinic.
Patients who were at least 18 years of age and attended the ambulatory Cardiac Clinics at the Royal Columbian Hospital, a tertiary care hospital in New Westminster, British Columbia, between July 1, 2016, and July 1, 2018, were eligible for the study. Patients with atrial fibrillation or heart failure can be referred to the Cardiac Clinics to be seen by an interdisciplinary health care team. Patients were eligible for the study if they had a diagnosis of atrial fibrillation and/or heart failure, had an active telephone number, self-administered their medications and could communicate in English. Eligible patients were contacted via telephone. Patients were excluded from the study if they were discharged from the clinics at any time during the study, meaning they were no longer followed by the clinics for their condition, or if there was no successful contact following 3 phone call attempts.
Medication reviews were conducted by phone by the primary author, who is a pharmacist, for internal consistency. Demographic information was collected from a combination of electronic medical records (EMRs), patients’ clinic charts and patient interviews.
The interview consisted of demographic questions followed by a medication review of the patient’s current, over-thecounter and NHP medications. Demographic questions were framed in a yes or no format. Patients were asked for the name, dose, route and frequency of all medications and the perceived indication and the duration of use. If patients were unaware of the indication for their medication, this was recorded on the data sheet. If patients were unaware of the length of time they had been taking the medication, they were prompted by periods of time less than 3 months, less than 6 months, less than 1 year or over 1 year. Products that patients listed were classified in the following categories based on Canada’s NHP database: vitamins or minerals, herbal remedies, homeopathic medicines, traditional medicines, probiotics, amino acids or fatty acids. This list was compared to the most recent medication list found in the patient’s clinic chart, which is updated at each visit by a nurse practitioner, nurse or pharmacist. NHP documentation was considered complete if the NHP name was listed and did not require dose, route or frequency to be considered accurate.
Patients’ cardiac conditions, age, gender, coexisting morbidities and cardiovascular medications were obtained from their medical charts for cross-referencing purposes. Comorbidities recorded included hypertension, dyslipidemia, chronic obstructive pulmonary disease, asthma, cerebral vascular event, myocardial infarction (MI) and diabetes mellitus. All patients provided consent for access to their health records as part of the clinic care upon the initial visit to the clinic and were asked to reconfirm consent to the medication reconciliation upon successful contact.
Descriptive statistics were employed to analyze NHP use and patient demographics. Prevalence of NHP use and drug interactions was reported using frequencies and percentages. The researchers sought a sample size of 100 patients, which would yield approximately 10% of the total target population of clinic patients and provide a confidence interval of 10%. An online random number sequence generator was used to select patients from the complete list of clinic patients. If the patient selected from the random number sequence generator was not eligible or did not provide consent, the next patient in the sequence was reviewed for eligibility. Given the quality improvement nature of the project, ethics approval from the governing body was not required and an exemption was obtained from the institutional ethics board.
There were 201 patients contacted during the study period; 119 patients provided consent and completed successful interviews. Eighty-two patients were excluded from the study (Figure 1). Demographic information is provided in Table 1. Of the 119 patients included, 71 patients had atrial fibrillation, 44 patients had heart failure and 4 had both conditions. The average age of patients was 64.8 years and 69% of the patients were male. Hypertension was present in 55% of patients, dyslipidemia in 45% of patients and diabetes in 25% of patients.
Of the 119 patients interviewed, 74 (62%) reported NHP use. The total number of products used in this population was 239 (Table 2). The most common type of NHP used was vitamins and minerals, with vitamin D being the most prevalent (26.9%), followed by multivitamins, omega-3 or omega-3-6-9 and calcium. No traditional Chinese medicines were identified. Nearly all products were used orally (98%), and 83% were used on a regularly scheduled basis. A higher percentage of female patients in the study were taking NHPs compared to male patients (78% vs 55%). The mean age of those taking NHPs was 66, while those not taking NHPs was 63. The number of cardiovascular medications, health conditions and ethnicity did not appear to differ between those taking NHPs and not. Among heart failure patients, 70% of the population reported NHP use and 56% of atrial fibrillation patients. Finally, most patients who were using NHPs used 1 or 2 products. Two patients used more than 10 NHPs (Figure 2). A further breakdown of the specific NHPs recorded for each cardiac population can be found in Appendix 1.
Reported indications for NHP use were variable and are shown in Figure 3. The most common indication for NHP use was “for good health,†which was reported for 23% of products. Bone health, heart health and nutrition and diet were other commonly cited indications. There were over 60 reported indications listed, which highlights the diverse use of NHPs. Patients reported being uncertain of the indication for 16% of the products.
The Lexicomp and Natural Medicines databases were used to assess drug interactions between patients’ NHPs and cardiac medications. On average, patients were using 4 cardiac medications, including antihypertensives, anticoagulants, antiarrhythmics, antiplatelets, diuretics and statins. Of the 90 interactions identified by Lexicomp, no action was needed for 10%. However, drug therapy monitoring was recommended for 82%. Eight percent of interactions required modification of drug therapy. In contrast, Natural Medicines suggests that all interactions reviewed were not clinically relevant. The most common potential implications noted were increased bleeding risk, decreased efficacy of anticoagulants or increased risk of hypotension. For example, interactions involving ginger, taurine and turmeric with anticoagulants and antiplatelet agents increase bleeding risk. Only 13 of 74 patients using NHPs had no interactions identified by either database. Other potential complications of cardiac drug and NHP interactions included increased clotting risk, higher and lower blood pressure and increased risk of arrhythmias.
Only one-quarter (n = 18, 24%) of patients had complete documentation of NHPs in the clinic chart.
This study demonstrates that NHP use is common among patients in the cardiac outpatient clinics population. Interactions causing potential for harm were flagged in 90 combinations with NHPs. Additionally, this study suggests that health care providers do not accurately record NHP use in the outpatient settings. Documentation of NHPs is an integral aspect of medication reconciliation, as it helps to identify patient-specific cases in which interactions may have an impact on drug efficacy or patient safety.
Previous studies have evaluated the cardiovascular populations’ use of NHPs. Ackman et al.9 found patients with congestive heart failure at an outpatient clinic may use vitamins and minerals in up to 60% of cases, which mirrors our results. Alherbish et al.6 sought to quantify the use of NHPs among the inpatient cardiac population and the most accurate method to collect NHP information from patients. They found that NHP use was higher than the average population, at 78%. Additionally, the study found that pharmacists obtained the most accurate information regarding NHP use of all health care practitioners.
Our study shows that a higher percentage of female patients were taking NHPs, and the NHP group had a higher mean age. The previous literature confirms this.6,9,10 This is especially significant, as older patients are usually less represented in clinical studies and are more susceptible to drug interactions and adverse events.11
Some NHPs have been more widely tested for efficacy than others and are recommended by health care professionals. Within our study, vitamin D was shown to be the most widely used NHP. Health Canada indications for vitamin D include osteoporosis, chronic kidney disease and vitamin D deficiency.12 In contrast, other NHPs, such as omega-3 supplements, which were commonly used for heart health among patients in the study, do not have evidence supporting their use in patients with atrial fibrillation or heart failure, as per the American Heart Association.13 Additionally, new information on NHPs is constantly emerging that points to potential safety issues that were previously unknown. For example, in the past decade, calcium supplements that were previously deemed beneficial for bone health have been found to be associated with increased cardiovascular events.14-16 Kuanrong et al.15 saw a higher MI risk over 11 years in patients who used supplements and more so in those who used only calcium supplementation with their medication regimen. Reid et al.17 suggested that dietary calcium is less likely to be the cause of cardiovascular dysfunction when contrasted with calcium supplementation. This is due to the acute change in serum calcium, which can adversely affect vascular health, often prominent in renal disease. Both studies concluded that further research regarding the impact of supplemental calcium intake should be pursued. As research continues to evolve around NHPs, it is integral that patients consult health care professionals to obtain the most accurate and patient-specific advice.
A 2005 study suggested that patients may spend over US$600 million on these accessible products.18 These NHPs may contribute to potentially dangerous drug interactions and pose an unnecessary expense for the patient. Patients and their health care providers should discuss each NHP to assess its necessity and efficacy. This is important, especially given that in this study, the most common indication for NHP use was “for good health.â€
Interactions between cardiac medications and NHPs were prevalent in the study. When reviewed in combination with patient-specific factors, these drug interactions may severely compromise patient safety. In our study, the most significant interaction was found with ginger and turmeric use in patients using antiplatelets or anticoagulants. Lexicomp recommended potential therapy modification, given that both turmeric and ginger have been found to inhibit platelet function, which increases risk of bleeding.19 This highlights the importance of reviewing NHPs for risk vs benefit.
In order to assess this individual risk, pharmacists and other health care professionals require documentation of NHPs and the patient’s entire medication regimen. Patients often do not view NHPs to be as relevant as prescription medications and may not disclose their usage despite being asked for a complete medication history.20 Many patients also do not feel it is necessary to discuss the use of NHPs prior to initiation.21 The interview technique used by Alherbish et al.6 demonstrated that standardized medication reconciliation is best for collecting NHP information. The incomplete BPMH collected by some health care providers, as demonstrated in this study, means that the use of NHPs by these patients was not assessed by a health care professional and leaves potential for patient harm. In order to assess for patient-specific side effects and interactions, a BPMH, including NHPs, must be accurate and complete. Given that patients with cardiac conditions are already at high risk of experiencing drug interactions, attention to NHP use is integral to ascertain if an unwanted side effect is caused by an NHP. BPMH requires the effort of both health care providers and patients, and education for both groups regarding NHP use is clearly warranted. Improvement in this area could involve integrating questions regarding NHP use into the patient medication reconciliation, as well as using the specific categories of NHP, with examples to prompt the patients to report a complete history. Additionally, patients should be reminded to bring into each clinic visit all products that they use, including NHPs.
Strengths of this study include its direct one-to-one structured telephone interview format, for which 1 interviewer was able to collect all information, reducing interindividual bias. Additionally, this study is the first to look at both NHP use in an outpatient population together with assessment of documentation and drug interactions. Novel components of our study include asking patients about reasons for using NHPs and completing an interaction analysis. Information regarding reasons for use may be used to provide better patient-specific information regarding these products in the future and offer an opportunity for health care providers to educate patients further. The interaction checks that were completed allowed assessment of the impact that NHPs have on overall patient health. These implications should be brought to the forefront of practitioners’ minds when completing a comprehensive assessment. Highlighting the common implications of interactions between NHPs and cardiac medications is an integral part of increasing practitioner education.
Despite its strengths, this study has several limitations. Although the categorization of NHPs can be considered a strength of the study, for ease of collection of information, certain products, such as probiotics and protein powders, were grouped as a singular product without acknowledgment of the product’s individual ingredients. This could result in fewer interactions being suggested by the databases. Lexicomp and Natural Medicines databases presented different information regarding identification of specific interactions and categorizing the severity of these interactions. Clinical judgment should be used when reviewing interactions. Patients were not asked during interviews about the context of how they decided to pursue therapy with each NPH (e.g., health care provider recommendation, family and friends’ encouragement, advertising, seeking information online). A health care professional available at the clinics, such as a pharmacist, dietitian or nurse practitioner, may have completed a thorough review of the perceived benefits of therapy. Recall bias among patients will also result in incomplete medication lists. Further studies should encompass where patients received this health advice. Lastly, patient charts are only as up to date as the patients’ last visit to the clinic, which may have been over a year prior to study enrolment. In cases where patients just recently began using an NHP, it may not be documented in the chart, which would lead to incomplete medication lists. Further studies should look to assess initiatives to improve documentation of NHPs and what prompted the patient to take them (health care professionals’ advice, anecdotal evidence, etc.). Additionally, finding the source by which the patient received information may assist with enhancing patient education.
NHP use is common among patients who attend outpatient cardiac clinics. Most NHPs used interact with cardiac medications, with potential implications including increased bleed risk and increased risk of thrombosis. Health care professionals often overlook documentation of NHP use in medication reconciliation. Initiatives to improve documentation of NHPs and further education to both health care providers and patients who use NHPs are necessary in the future.
From Saint Paul’s Hospital (Tress), Saskatoon, Saskatchewan, and the Royal Columbian Hospital (Chiu, Kwan, Gordon), Fraser Health Authority, New Westminster, British Columbia. Contact Kaitlyn.am.tress@gmail.com.
Author Contributions: K. Tress was responsible for design and methodology, wrote the final draft; A. Chiu initiated the project, was responsible for design and methodology, supervised project, reviewed final draft; L. Kwan supervised project, reviewed final draft; and W. Gordon reviewed final draft.
Funding: The authors received no financial support for the research, authorship and/or publication of this article.
Declaration of Conflicting Interests: The authors declared no potential conflicts of interest with respect to the research, authorship and/or publication of this article.
ORCID iDs: Kaitlyn Tress https://orcid.org/0000-0003-4326-798X
Ada Chiu https://orcid.org/0000-0002-3864-080X
Supplemental Material: Supplemental material for this article is available online.
