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Aromatherapy for treatment of hypertension:
a systematic reviewjep_1521 37..41
Myung-Haeng Hur RN PhD,1 Myeong Soo Lee PhD,2 Chan Kim MD PhD3 and
Edzard Ernst MD PhD FMedSci FSB FRCP FRCPEd4
1Professor, School of Nursing, Eulji University, Daejeon, South Korea2Principal Researcher, Division of Standard Research, Korea Institute of Oriental Medicine, Daejeon, South Korea and Honorary University Fellow,
Complementary Medicine, Peninsula Medical School, University of Exeter, Exeter, UK3Professor, Department of Physiology and Biophysics, School of Medicine, Eulji University, Daejeon, South Korea4Laing Chair in Complementary Medicine, Director and Professor, Complementary Medicine, Peninsula Medical School, University of Exeter,
Exeter, UK
Keywords
aromatherapy, hypertension, systematic
review
Correspondence
Dr Myeong Soo Lee
Division of Standard Research
Korea Institute of Oriental Medicine
Daejeon 305 811
South Korea
E-mail: [email protected];
Accepted for publication: 10 May 2010
doi:10.1111/j.1365-2753.2010.01521.x
AbstractObjectives The objective of this review is to systematically review the evidence for the
effectiveness of aromatherapy in the treatment of high blood pressure.
Methods Twelve databases were searched from their inception through December 2009.
Controlled trials testing aromatherapy in patients with hypertension of any origin that
assessed blood pressure were considered. The selection of studies, data extraction and
validations were performed independently by two reviewers.
Results One randomized clinical trial (RCT) and four non-randomized controlled clinical
trials (CCTs) met our inclusion criteria. The one RCT included tested the effects of
aromatherapy as compared with placebo and showed significant reduction of systolic blood
pressure and diastolic blood pressure. All of the four CCTs showed favourable effects of
aromatherapy. However, all of the CCTs also had a high risk of bias.
Conclusion The existing trial evidence does not show convincingly that aromatherapy is
effective for hypertension. Future studies should be of high quality with a particular
emphasis on designing an adequate control intervention.
Introduction
High blood pressure (BP) is a major, independent risk factor for
cardiovascular disease (CVD). Many cardiovascular events would
be preventable if cardiovascular risk factors could be eliminated
[1]. Complementary therapies are popular and frequently used by
patients with CVD[2]. Many complementary therapy options exist,
and more than 95 different complementary therapies have been
recommended for hypertension [3]. Aromatherapy is one option.
Aromatherapy is the therapeutic use of essential oils fromplants [4]. Essential oils can be absorbed into the body via the
skin or the olfactory system. Many studies have found that olfac-
tory stimulation produces immediate changes in physiological
parameters such as blood pressure (BP), muscle tension, pupil
dilation, skin temperature, pulse rate and brain activity [47].
Clients and practitioners of aromatherapy perceive such treat-
ments to be effective, but physicians are often sceptical of this
claim. Several textbooks have also asserted the favourable thera-
peutic effects of aromatherapy for CVDs including hypertension
[810]. However, no systematic reviews for this condition are
currently available.
The aim of this systematic review was to summarize and criti-
cally assess the evidence from controlled clinical trials for or
against the effectiveness of aromatherapy as an anti-hypertensive
treatment.
Methods
Data sources
The following electronic databases were searched from theirinception up to December 2009: Medline, CINAHL, EMBASE,
PsycInfo, The Cochrane Library 2009 (Issue 4), 6 Korean Medical
Databases (Korean Studies Information, DBPIA, Korea Institute
of Science and Technology Information, Research Information
Center for Health Database, KoreaMed, National Assembly
Library), and Chinese Medical Database (CNKI), as well as three
Japanese electronic databases (Japan Science and Technology
Information Aggregator Electronic, Journal@rchive and Science
Link Japan). The search phrase used was ([aromatherapy OR
aroma*] AND [blood pressure OR hypertension]). We also manu-
ally searched our departmental files and relevant journals, FACT
Journal of Evaluation in Clinical Practice ISSN 1365-2753
2010 Blackwell Publishing Ltd, Journal of Evaluation in Clinical Practice18 (2012) 3741 37
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(Focus on Alternative and Complementary Therapies) and For-
schende Komplementrmedizin und Klassische Naturheilkunde
(Research in Complementary and Classical Natural Medicine), up
to December 2009. In addition, the references in all articles studied
were manually searched for additional relevant articles.
Study selectionAll prospective randomized clinical trials (RCTs) and non-
randomized controlled clinical trials (CCTs) were included if the
patient population included those with hypertension who received
aromatherapy alone or combined with other treatments. Trials with
designs that did not allow for an evaluation of the effectiveness of
the intervention (e.g. by using treatments of unproven efficacy in
the control group or comparing two different forms of aroma-
therapy) were excluded. Dissertations and abstracts were included.
Uncontrolled studies, case series and case reports were excluded.
Data extraction and assessment of the
risk of bias
Hard copies of all articles were obtained and read in full by two
independent reviewers (MHH, MSL). Data from the articles were
validated and extracted according to pre-defined criteria (Table 1).
The risk of bias was assessed using the Cochrane classification as
represented by four criteria [11]: sequence generation, incomplete
outcome measures, blinding and allocation concealment. Discrep-
ancies were resolved through discussion between two reviewers
(MHH, MSL) and, if needed, by seeking the opinion of a third
reviewer (EE). There were no disagreements between the three
reviews regarding the assessment of the risk of bias.
Results
The searches identified 74 potentially relevant studies, five ofwhich met our inclusion criteria (Fig. 1). The key data are sum-
marized in Table 1 [1216]. A total of 200 participants were
included in these trials. Four trials originated from Korea [1215],
and one study was conducted in the UK [16]. Four trials [1215]
used aromatherapy as inhalation or local topical treatment, and
the other [16] used aromatherapy with massage. The number of
aromatherapy sessions ranged from 1 to 28. The session duration
ranged from 2 minutes to 45 minutes. Three [1416] of the
included trials adopted a two-armed parallel-group design and one
[13] a three-armed parallel group design, whereas the other [12]
used a cross-over design.
Study quality
Among the included trials, most had a high risk of bias. One
RCT reported sequence generation and used patient blinding [12].
The others also had a potential high risk of bias, despite the
employment of patient blinding by two CCTs [12,13].
Outcomes
Aromatherapy versus placebo treatment
Two trials [12,13] compared the effect of aromatherapy as com-
pared with placebo treatment on BP values in pre-hypertension
middle-aged women or essential hypertension patients. One RCT
[12] showed significant reduction of systolic blood pressure (SBP)
and diastolic blood pressure (DBP) in the aromatherapy group as
compared with the placebo group. The other CCT also reported
favourable effects of aromatherapy as compared with placebo
on the reduction of SBP and DBP [13]. One RCT [12] reported
significant changes in epinephrine (E) and norepinephrine (NE)
elicited by aromatherapy as compared with placebo, whereas the
CCT [13] failed to do so.
Aromatherapy versus no treatment
Three CCTs tested aromatherapy as compared with no treat-
ment on BP in patients with essential hypertension [1315]. Two
CCTs [13,15] reported favourable effects of aromatherapy as
compared with no treatment on the reduction of SBP and DBP,
whereas the other CCT [14] did not report any such inter-group
difference.
Aromatherapy plus massage versus placeboplus massage
One CCT [16] tested aromatherapy massage as compared with
placebo plus massage on BP. Both treatments improved BP read-
ings. However, the details of these results were not reported.
Discussion
To the best of our knowledge, this is the first systematic review
of the effectiveness of aromatherapy for high blood pressure.
The results suggest that aromatherapy is more effective than
placebo in reducing SBP and DBP. However, the existing trial
evidence does not show convincingly that aromatherapy is effec-
tive in reducing blood pressure due to numerous drawbacks ofthe primary studies. .
The quality of the included studies was assessed based on the
descriptions of sequence generation, blinding, incompleteness of
outcome measures and allocation concealment. Among the five
studies that we included, only one [12] was randomized. The rest
were open to selection bias, which can generate false-positive
findings. Two studies [12,14] were published in a thesis, which had
not gone through the formal peer review process. Furthermore,
two CCTs failed to report the detailed results of statistical analysis
[14,16]. All of the studies were burdened with a high risk of bias.
Thus, the reliability of the evidence presented is clearly limited.
The mechanisms by which aromatherapy reduced BP may be
related to sympathetic nervous system (SNS) modulation. Aroma-therapy lowered the level of NE and E. This effect is compatible
with suppression of SNS activity as NE and E have been directly
linked to SNS [17]. However, more basic research is needed
to fully understand the mechanisms underlying the effects of
aromatherapy.
The next question that arises concerns the safety of aroma-
therapy. None of the reviewed studies reported any adverse events
related with aromatherapy. Aromatherapy appears to be generally
safe, and serious adverse effects have not been reported. Adverse
effects were not the focus of this review; regardless, the safety of
aromatherapy requires further research.
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The limitations of our systematic review and any systematic
review in general pertain to the potential incompleteness of the
evidence reviewed. We aimed to identify all controlled clinical
trials on the topic. The distorting effects on systematic reviews and
meta-analyses arising from publication bias and location bias are
well documented [18,19]. In this review, there were no restrictions
in terms of publication language, and many different databases
were queried. We are confident that our search strategy located all
of the relevant data; however, a degree of uncertainty remains.
Moreover, selective publishing and reporting can be major causes
of bias. It is conceivable that several negative RCTs remain unpub-
lished, thus distorting the overall picture. Another possible source
of bias is the fact that most of the included trials were carried outin Korea, regions that have been shown to produce almost no
negative studies [20]. Further limitations of our review are the
potentially poor quality of the primary data and poor reporting of
results, which were highly heterogeneous in virtually every
respect. To establish the role of aromatherapy in the management
of hypertension patients, adequately designed trials are required.
Collectively, the existing trial evidence is not convincing
and does not show aromatherapy to be an effective modality for
managing hypertension. Future studies should be of high quality,
with a particular emphasis on designing adequate and appropriate
control groups.
Acknowledgement
This work was supported by Mid-career Researcher Program
through NRF Grant funded by MEST (No. 2009-0083800).
References
1. World Health Organization (2002) WHO CVD-risk management
package for low- and medium-resource settings. Available at: http://
whqlibdoc.who.int/publications/2002/9241545852.pdf (last accessed
2 February 2010).
2. Yeh, G. Y., Davis, R. B. & Phillips, R. S. (2006) Use of complementary
therapies in patients with cardiovascular disease. The AmericanJournal of Cardiology, 98 (5), 673680.
3. Ernst, E. (2005) Complementary/alternative medicine for hyperten-
sion: a mini-review.Wiener Medizinische Wochenschrift, 155 (1718),
386391.
4. Ernst, E., Pittler, M. H., Wider, B. & Boddy, K. (2006) The Desktop
Guide to Complementary and Alternative Medicine. Edinburgh:
Elsevier Mosby.
5. Diego, M. A., Jones, N. A., Field, T., Hernandez-Reif, M., Schanberg,
S., Kuhn, C., McAdam, V., Galamaga, R. & Galamaga, M. (1998)
Aromatherapy positively affects mood, EEG patterns of alertness and
math computations. The International Journal of Neuroscience, 96
(34), 217224.
Publications identified (n=74)
Publications excluded after screening the title and
abstract (n=28)
Reasons: Not related to aromatherapy (n=5)
Not related to hypertension (n=6)
Not clinical studies (n=12)
In vivostudies (n=3)
Duplicated publications (n=2)
Full text for detailed evaluation (n=46)
Excluded after reading the full text (n=41)Reasons:
Case study (n=2)
UOSs but not related to hypertension (n=6)
CCTs but not re lated to hypertension (n=27)
RCTs but not re lated to hypertension (n=6)
Included studies (n=5)RCT (n=1)
CCTs (n=4)
Figure 1 F lo w chart of tri al sel ecti on
process. CCT, non-randomized controlled
clinical trial; RCT, randomized clinical trial;
UOS, uncontrolled observational study.
Aromatherapy for hypertension M-H. Hur et al.
2010 Blackwell Publishing Ltd40
-
7/25/2019 Aromatherapy for treatment of hypertension a systematic review.pdf
5/6
6. Field, T., Diego, M., Hernandez-Reif, M., Cisneros, W., Feijo, L.,
Vera, Y., Gil, K., Grina, D. & Claire He, Q. (2005) Lavender fragrance
cleansing gel effects on relaxation. The International Journal of
Neuroscience, 115 (2), 207222.
7. Lorig, T. S. & Schwartz, G. E. (1988) Brain and odor: I. Alteration of
human EEG by odor administration.Psychobiology, 16, 281284.
8. Buckle, J. (2004) Aromatherapy and cardiovascular disease. In
Complementay and Alternative Cardiovascular Medicine (eds R. A.Stein & M. C. Oz), pp. 239254. Totowa, NJ: Humana Press Inc.
9. Buckle, J. (2003) Clinical Aromatherapy. London: Churchill Living-
stone, Elservier.
10. Kayne, S. B. (2009) Aromatherapy. In Complementary and Alter-
native Meidicine (ed. S. B. Kayne), pp. 341381. London: Pharma-
ceutical Press.
11. Higgins, J. P. T. & Altman, D. G. (2008) Assessing Risk of Bias in
Included Studies. In Cochrane Handbook for Systematic Reviews
of Interventions (eds J. P. T. Higgins & S. Green), pp. 187241. West
Sussex: Wiley-Blackwell.
12. Jung, Y. J. (2007) Effects of Aromatherapy on Blood Pressure, Heart
Rate Variability, and Serum Catecholamines in the Pre-Hypertension
Middle Aged Women. Seoul: Catholic University.
13. Hwang, J. H. (2006) [The effects of the inhalation method using
essential oils on blood pressure and stress responses of clients with
essential hypertension]. Taehan Kanho Hakhoe Chi, 36 (7),11231134.
14. Ma, S. C. (2005) Effects of Aromatherapy for Hypertension Patients.
Seoul: Kyonggi University.
15. Jang, H. H. (2002) A clinical study on the effects of the aroma-
therapy for hypertension. Journal of Orient Neuropsychiatry, 13 (1),
318.16. Basnyet, J. (1999) The effect of aromatherapy treatment on raised
arterial blood pressure pilot study. Positive Health, 39, 2023.
17. James, G. D. (1989) The relation of norepinephrine to blood pressure
is independent of acculturation in Western Samoan men. American
Journal of Hypertension, 2 (6 Pt 1),471473.
18. Ernst, E. & Pittler, M. H. (1997) Alternative therapy bias.Nature, 385
(6616), 480.
19. Pittler, M. H., Abbot, N. C., Harkness, E. F. & Ernst, E. (2000)
Location bias in controlled clinical trials of complementary/alternative
therapies.Journal of Clinical Epidemiology, 53 (5), 485489.
20. Vickers, A., Goyal, N., Harland, R. & Rees, R. (1998) Do certain
countries produce only positive results? A systematic review of
controlled trials. Controlled Clinical Trials, 19 (2), 159166.
M-H. Hur et al. Aromatherapy for hypertension
2010 Blackwell Publishing Ltd 41
-
7/25/2019 Aromatherapy for treatment of hypertension a systematic review.pdf
6/6
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