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Current management of patients taking herbal medicines: a survey of anaesthetic practice in the UK

McKenzie, A. G.*; Simpson, K. R.

European Journal of Anaesthesiology: August 2005 - Volume 22 - Issue 8 - p 597–602
doi: 10.1017/S0265021505001006
Original Article
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Background and objectives: Increasing numbers of patients taking herbal medicine products are presenting for anaesthesia and surgery. Anaesthetists need to consider the perioperative implications of herbal medicines and should, therefore, have some knowledge of this subject.

Methods: A postal questionnaire survey was sent to a random 5% of practising members of the Association of Anaesthetists of Great Britain and Ireland residing in the UK, to identify attitudes, practice and knowledge regarding herbal medicines.

Results: From 341 questionnaires there were 221 replies, a 65% response rate. Ninety per cent stated that they seldom or never asked patients about herbal medicine usage, yet 65% felt that there could be potentially harmful effects of herbal medicines in the perioperative period. There was a very poor level of knowledge with respect to the current management of 10 well-known herbal medicines. However, 75% agreed that information about perioperative usage of herbal medicines is important, and 77% felt that herbal medicines should be in the undergraduate medical curriculum. Reading was the usual source of herbal medicine product information. Most (82%) felt their knowledge of herbal medicine products and the implications in patient care were inadequate.

Conclusions: This sample of anaesthetists require education on herbal medicines. Suggestions for remedial action are given.

*Edinburgh Royal Infirmary, Department of Anaesthesia, Critical Care and Pain Medicine, Edinburgh, UK

University of Edinburgh, College of Medicine and Veterinary Medicine, Medical Teaching Organisation, Edinburgh, UK

Correspondence to: Alistair G. McKenzie, Department of Anaesthesia, Critical Care and Pain Medicine, Royal Infirmary, 51 Little France Crescent, Edinburgh, EH16 4SA, UK. E-mail: mckenzie_alistair@hotmail.com; Tel: +44 131 2423151; Fax: +44 131 2423174

Accepted for publication June 2005

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Introduction

The UK's annual total expenditure on complementary and alternative medicine is around £1.6 billion [1]. An important component of this is herbal medicine. Extrapolation from previous estimates [2,3] suggests that in the UK around £100 million is spent annually on retail licensed herbal medicine products. A further large sum is spent on unlicensed remedies [4]. Herbal medicines may have therapeutic activity and/or placebo effect, but adverse effects and interactions between different herbal remedies and between a herbal medicine and a conventional medicine are possible [2,5,6].

Anaesthetists encounter many patients taking herbal treatments and clearly, therefore, require some knowledge of this subject. Recent reviews have drawn attention to the need for anaesthetists to consider the perioperative implications of herbal medicine products [7-9], yet this does not seem to have been followed up. It was therefore decided to conduct a survey of attitudes, current practice and level of knowledge among anaesthetists in the UK. The generation of this information should be in the interests of good patient care.

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Methods

For the purposes of a questionnaire survey a random selection of 400 anaesthetists with UK addresses was obtained from the membership database of the Association of Anaesthetists of Great Britain and Ireland (about 5% of the database). One was no longer resident in the UK and 58 retired members were excluded. A questionnaire with a covering letter and stamped addressed reply envelope was sent to the remaining members. The questionnaire was designed to cover four areas:

- grade and any special interest,

- views on the importance of eliciting herbal medicinal product usage at preoperative assessment,

- action taken for divulged usage of 10 well-known products,

- views on knowledge and education pertaining to herbal medicinal products.

There were 11 questions in all (Appendix 1).

Non-responders were sent a second mailing and, if this was unproductive, telephoned where possible.

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Statistical analysis

Comparisons between consultants and trainees were performed using the χ2-test. For question 6 median score and range were calculated.

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Results

Of the 341 members sent questionnaires 221 replied, a 65% response rate. The responders comprised 160 consultants, 48 trainees and 13 non-consultant career grades. To compare responders with non-responders, details including date of full registration, specialist registration and address, were obtained from the Medical Register, 2004 published by the General Medical Council. In both groups the spread of registration dates and locations were similar.

Ninety percent of questionnaires were completed fully. (In 13 cases question 5 was not answered; in eight cases the back page, i.e. questions 7-11, was omitted despite the covering letter pointing out that there were 11 questions.) In analysing the results responses from consultants and trainees were compared. The responses of the non-consultant career grades could not be analysed because the size of this group was considered too small. A wide spread of special interests was declared (question 2).

In response to question 3, 199 (90%) stated that they seldom or never specifically asked patients about the use of herbal medicinal products. When asked about encounters with adverse interactions between anaesthetic drugs and these products (question 4), 202 (91%) stated that they had never seen this. However, 25 commented that they did not know, because any such usage had not been ascertained. There were 18 who stated that they had encountered such adverse interactions albeit seldom, although none had definite evidence.

One hundred and forty four (65%) responders agreed that there could be potentially harmful effects in the perioperative period (question 5). Thirty-eight (79%) trainees stated that this was the case, compared with 96 (60%) consultants (P < 0.05).

For question 6 on what to do about 10 well-known herbal products, a model answer was prepared using a consensus from peer-reviewed references [7-10] (Table 1).

Table 1

Table 1

Each paper was marked, awarding one mark for a correct answer, subtracting one mark for a wrong answer and awarding zero for a blank or ‘don't know’. Thus, the maximum possible score for question 6 was 10 marks and the minimum possible score was −7. The individual totals ranged from −4 to +8 (median score 2) and revealed a very poor level of knowledge: 138 anaesthetists (62%) scored zero or less. Only 43 (19%) obtained a score of 3 or more out of 10. Looking at the categories of special interest (question 2), no group had significantly better or worse knowledge than the others.

The majority (166; 75%) agreed that information about perioperative usage of herbal products is important. This was the opinion of 43 (90%) of trainees compared to 113 (71%) of consultants (P < 0.01).

One hundred and seventy (77%) agreed that herbal product usage and information should be included in the undergraduate medical curriculum. The most common source of anaesthetists' knowledge on herbal products was reading (73%), whereas the Internet was the source for only 20%. Only two people declared the medical undergraduate curriculum as their source of this information.

The majority (181; 82%) did not feel that their knowledge on herbal medicinal products and the implications for patient care were adequate. Further analysis of those who felt that they did have adequate knowledge in this area revealed that their opinion was not supported by the evidence. All but four had scored less than 3 out of 10 in the test question. Finally, 49% of anaesthetists declared that they would be interested in attending a seminar on herbal medicinal products and anaesthesia.

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Discussion

It is paradoxical that the majority (90%) of this sample of anaesthetists seldom or never ask patients about usage of herbal medicine products, despite declaring that there can be potentially harmful effects in the perioperative period (65%) and that information on such usage is important (75%). It is probable that they simply forget - a prompt such as the words ‘herbal medicines’ added to the preoperative assessment section of printed anaesthetic charts could solve this problem. Surveys have shown that disclosure rates of complementary medicine usage to physicians are low - most patients have to be specifically asked [11,12].

This survey drew only anecdotal accounts of adverse reactions implicating herbal products with no mention of reporting to the Medicines and Healthcare products Regulatory Agency. The Yellow Card for reporting suspected adverse drug reactions to the Committee on Safety of Medicines has invited details of herbal remedies since 1996. At present we can infer that most anaesthetists are not reporting possible adverse interactions with herbal medicines, since they do not know of such usage. Data on interactions between drugs used in anaesthesia and herbal products is sadly lacking, whether adverse or beneficial.

The 10 herbal medicines chosen for the test question included eight that are used commonly in UK [13] and two others: ephedra, which anaesthetists are expected to know well, and kava, which featured in a recent newsletter circulated to medical practitioners when it was prohibited [14]. The level of UK anaesthetists' knowledge of herbal medicines is unequivocally poor. We are unaware of any similar survey for any other specialty in the UK. In a recent questionnaire assessment of herbal medicinal product knowledge involving 44 Canadian anaesthesiologists, only 32% of the questions were answered correctly [15].

Questions arise from the corollary that anaesthetists require education about these products. Since 2003 the American Society of Anesthesiologists (ASA) website has featured information on what anaesthesiologists should know about patients' use of herbal medicines [16], but nothing similar has been produced in the UK. Since most anaesthetists feel that their knowledge of the subject is inadequate, coverage in standard textbooks of anaesthesia should be welcomed. From a safety viewpoint examination questions on herbal products would provide a means of assessment. For undergraduates, inclusion of this in the medical curriculum seems a logical solution - the majority of anaesthetists endorse this.

Courses on complementary medicine have been increasingly offered to medical students in the UK through the 1990s, but mainly on an optional basis [17]. Inclusion of herbal product information within the core curriculum could equip all future doctors to be competent in the safety and efficacy issues.

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Acknowledgements

We thank the Association of Anaesthetists of Great Britain and Ireland for providing a percentage of their membership database, and all the anaesthetists who responded to the questionnaire.

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References

1. Ernst E. The role of complementary and alternative medicine. BMJ 2000; 321: 1133-1135.
2. Ernst E. Risks associated with complementary therapies. In: Dukes MNG, Aronson JK, eds. Meyler's Side Effects of Drugs, 14th edn. Amsterdam, The Netherlands: Elsevier Science B.V., 2000: 1649-1651.
3. House of Lords Select Committee. Report on role of complementary and alternative medicine. http://www.chiro.org/alt_med_abstracts/FULL/House_of_Lords/CHAPTER_V-D.html
4. Herbal Medicines. Pharmaceut J 1994; 253: 75.
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10. Ang-Lee MK, Moss J, Chun-Su Y. Herbal medicines and perioperative care. JAMA 2001; 286: 208-216.
11. Eisenberg DM, Kessler RC, Foster C, Norlock FE, Calkins DR, Delbanco TL. Unconventional medicine in the United States. Prevalence, costs, and patterns of use. N Engl J Med 1993; 328: 246-252.
12. Eisenberg DM, Davis RB, Ettner SL et al. Trends in alternative medicine use in the United States, 1990-1997. Results of a follow-up national survey. JAMA 1998; 280: 1569-1575.
13. McKenzie AG. Herbal medicines in the United Kingdom. Anaesthesia 2003; 8: 597-598.
14. Medicines and Healthcare products Regulatory Agency (MHRA). Kava-kava and hepatotoxicity. Curr Prob Pharmacovigil 2003; 29: 8.
15. Lennox PH, Henderson CL. Herbal medicine use is frequent in ambulatory surgery patients in Vancouver Canada. Can J Anaesth 2003; 50: 21-25.
16. American Society of Anesthesiologists. What You Should Know About Your Patients' Use of Herbal Medicines and Other Dietary Supplements. http://www.asahq.org/patientEducation.htm.
17. Zollman C, Vickers A. ABC of complementary medicine: what is complementary medicine? BMJ 1999; 319: 693-696.
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Appendix 1

Table

Table

Table

Table

Keywords:

MEDICINE; HERBAL; INTRAOPERATIVE COMPLICATIONS; POSTOPERATIVE COMPLICATIONS; HERB-DRUG INTERACTIONS; EDUCATION; MEDICAL; undergraduate; graduate; continuing

© 2005 European Society of Anaesthesiology