Relative effectiveness of clinic and home blood pressure monitoring compared with ambulatory blood pressure monitoring in diagnosis of hypertension: systematic review
BMJ 2011; 342 doi: https://doi.org/10.1136/bmj.d3621 (Published 24 June 2011) Cite this as: BMJ 2011;342:d3621All rapid responses
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We have read with interest the article "Relative effectiveness of
clinic and home blood pressure monitoring compared with ambulatory blood
pressure monitoring in diagnosis of hypertension: systematic review" by
Hodgkinson et al. (2011) (1). One of our recently published study has been
included in the systematic review of the test performance of the diagnosis
of hypertension by clinic measurement compared with the reference standard
of ambulatory monitoring (2).
We find useful to the readers to point out the fact that manual blood
pressure (BP), as measured in our study, is not equivalent to clinic BP.
Indeed, manual blood pressure and ambulatory blood pressure were assessed
using the same semi-automatic device, in the same environmental settings.
These measures were made by a trained technician instead of a physician
and at the workplace (in a dedicated room) rather than in a medical
environment. Consequently, the prevalence of white-coat hypertension was
reduced substantially (1.4 %) (3, 4), whereas that of masked hypertension
remained within the range of previous studies (i.e. 15%) (5). This
explains why our study has distinctive predictive properties (as shown in
table 5), and why it is standing on the edge of the ROC curve (as shown in
Fig. 3). As our study had a large sample size (N= 2 370), this precision
is important to keep in mind while interpreting the results from
Hodsgkinson's review.
1. Hodgkinson J, Mant J, Martin U, Guo B, Hobbs FD, Deeks JJ, et al.
Relative effectiveness of clinic and home blood pressure monitoring
compared with ambulatory blood pressure monitoring in diagnosis of
hypertension: systematic review. BMJ. 2011;342:d3621.
2. Trudel X, Brisson C, Larocque B, Milot A. Masked hypertension:
different blood pressure measurement methodology and risk factors in a
working population. J Hypertens. 2009 May 13;27:1560-7.
3. Myers MG, Valdivieso M, Kiss A. Use of automated office blood
pressure measurement to reduce the white coat response. J Hypertens. 2009
Feb;27(2):280-6.
4. Ogedegbe G, Pickering TG, Clemow L, Chaplin W, Spruill TM,
Albanese GM, et al. The misdiagnosis of hypertension: the role of patient
anxiety. Arch Intern Med. 2008 Dec 8;168(22):2459-65.
5. Verberk WJ, Thien T, de Leeuw PW. Masked hypertension, a review of
the literature. Blood Press Monit. 2007 Aug;12(4):267-73.
Competing interests: No competing interests
Professor McManus and colleagues are to be congratulated on their
systematic review of the relative effectiveness of clinic and home blood
pressure monitoring compared with ambulatory blood pressure monitoring in
the diagnosis of hypertension [1]. This review played an important part in
widespread changes concerning the diagnosis of hypertension in the UK
proposed by the National Institute for Health and Clinical Excellence
(NICE) [2]. The authors clearly indicate the difficulties they faced in
summarising a discordant and complex literature. We fully support the move
towards much wider use of ambulatory blood pressure monitoring, a vital
tool for diagnosis and monitoring of hypertension but we believe that
there is an important limitation in their analysis relating to the
definition of hypertension that requires further consideration.
In routine clinical practice both systolic and diastolic pressure are
reported, and both are usually taken into consideration when making a
diagnosis of hypertension. Two common patterns of blood pressure elevation
are apparent in Western populations. Elevation of systolic and diastolic
pressure is the predominant form of hypertension in middle-aged
individuals, and this reflects the underlying pathology of increased
peripheral resistance. In contrast isolated systolic hypertension is the
predominant form in older people, and results from stiffening or
arteriosclerosis of the large arteries [3].
As indicated by the authors, criteria for defining hypertension during
ambulatory monitoring differ between studies, and may not be reported in
detail [1]. The diagnostic threshold for hypertension during ambulatory
monitoring in papers in the McManus analysis was 135/85. However, this
threshold could imply a systolic blood pressure >135mmHg AND diastolic
blood pressure >85mmHg, or alternatively, a systolic blood pressure
>135mmHg OR diastolic blood pressure >85mmHg. This distinction is
important because the former interpretation would exclude individuals with
isolated systolic hypertension (ISH) and isolated diastolic hypertension
(IDH), while only patients with systolic-diastolic hypertension (SDH) will
be included. The authors report that they pragmatically included papers
using both of these inclusion criteria, and others where it was unclear
[Dr J Hodgkinson, personal correspondence].
A recent study of patterns of hypertension within the untreated
hypertensive NHANES population showed that, based on clinic blood
pressures, only 21.3% of the population fell within the SDH subgroup, with
58.6% having ISH [4]. Therefore, studies included in the systematic review
where the diagnostic threshold was systolic blood pressure >135mmHg AND
diastolic blood pressure >85mmHg could have included less than a
quarter of the hypertensive population. If the relationship between clinic
and ambulatory blood pressure differs depending on clinic blood pressure
pattern this would have major implications for how the calculated
sensitivity and specificity of ambulatory blood pressure monitoring for a
diagnosis of hypertension determined by the systematic review translate to
the general population.
Although this may appear to be only an esoteric point of academic
interest, in fact it has major health policy implications. The new NICE
guidance on management of hypertension in adults in primary care proposes
implementation of widespread use of ambulatory blood pressure monitoring
for the diagnosis of hypertension. This recommendation is based upon a
complex and carefully constructed health-economic model using data taken
from this systematic review [5]. The model demonstrates ambulatory blood
pressure monitoring to be cost-effective since, despite initial set-up
costs, fewer people will subsequently require treatment. However, if there
is any doubt with regard to the whether the studies informing the
systematic review are representative of the general population, we propose
that, at a time of intense financial pressures for the health service, the
health economic model should be thoroughly reviewed before General
Practitioners are asked to make costly changes to their practice. In
addition, as indicated by the authors, there is a paucity of good-quality
data regarding the relationship between clinic and ambulatory blood
pressure and this provides an ideal opportunity for a large UK study to
assess prospectively the evidence base for, and potential benefit of, this
major change in practice before full implementation.
Finally, we do not wish to undermine the intensive and thorough work
that has underpinned the new guideline process. However, we feel that this
issue highlights the difficulty of developing health policy using evidence
before it has entered the public domain and been subject to rigorous
general review.
1.Hodgkinson J, Mant J, Martin U, Guo B, Hobbs FD, Deeks JJ, Heneghan
C, Roberts N, McManus RJ. Relative effectiveness of clinic and home blood
pressure monitoring compared with ambulatory blood pressure monitoring in
diagnosis of hypertension: systematic review. BMJ. 2011 Jun 24;342:d3621
2.NICE. Clinical guideline 127: hypertension (update), 2011.
http://guidance.nice.org.uk/CG127 (accessed September 11th 2011)
3.Franklin SS, Gustin W 4th, Wong ND, Larson MG, Weber MA, Kannel WB,
Levy D. Hemodynamic patterns of age-related changes in blood pressure. The
Framingham Heart Study. Circulation. 1997 Jul 1;96(1):308-15.
4.Franklin SS, Chow VH, Mori AD, Wong ND. The significance of low DBP
in US adults with isolated systolic hypertension. J Hypertens. 2011
Jun;29(6):1101-8.
5.Lovibond K, Jowett S, Barton P, Caulfield M, Heneghan C, Hobbs FR,
Hodgkinson J, Mant J, Martin U, Williams B, Wonderling D, McManus RJ. Cost
-effectiveness of options for the diagnosis of high blood pressure in
primary care: a modelling study. Lancet. 2011 Aug 23. [Epub ahead of
print]
Competing interests: No competing interests
The article "Relative effectiveness of clinic and home blood pressure
monitoring compared with ambulatory blood pressure monitoring in diagnosis
of hypertension: systematic review" by Hodgkinson et al (BMJ
2011;342:doi:10.1136/bmj.d3621) suggests that ambulatory blood pressure
monitoring (ABPM) should serve as a "gold standard", and if we accept
this, then about 25% of diagnosed hypertension cases are actually
overdiagnosis and should not be treated.
This view has a logical basis more than an evidence basis. The
approach to diagnosing and treating high blood pressure was never based on
ABPM. Assuming target values that were defined on one technique to be
valid on another is uncertain. It is likely that borderline cases will be
missed if we adopt the suggestion of the authors to perform ABPM before
starting any blood pressure lowering treatment.
Hypertension is probably on a continuous spectrum rather than a
distinct state. The suggestion of using ABPM rather than repeated BP
measuring to decide about treatment is equivalent to shifting the
threshold of treatment. Not to mention that ABPM is much less convenient
to the patient and more expensive to the system. And it will not stop
there; it makes the same sense to do the follow up using ABPM before any
decision on dosage change. We replace a simple method of patient self-
monitoring with a cumbersome technique that is probably needed only
occasionally.
Competing interests: No competing interests
After reading the article by Hodgkinsonet al [1], we want to discuss
a blood pressure (BP) measurement method that could be an acceptable
alternative to clinic and home BP measurements: the community pharmacy BP
(CPBP) measurement method.
The CPBP measurement method is readily available, widely demanded by
patients, and recommended by scientific societies in the area of
hypertension [2-4]. Moreover, this method presents certain advantages,
such as the availability of multiple BP measurements (in comparison to
clinic BP measurements), the selection of validated devices by a health
care professional or the supervision of the measurement conditions (in
comparison to home BP monitoring).
However, the usefulness of the CPBP measurement method in the
diagnosis or treatment of hypertension has not been adequately addressed
in previous studies [5]. In order to evaluate the usefulness of the CPBP
measurement method in clinical practice and research, the measurement
errors (both systematic and random) should be analyzed by assessing the
agreement between CPBP measurements and: (i) the same measurements
obtained on repeated occasions (repeatability studies) [6], and (ii) other
BP measurements obtained by the reference methods (concordance or
agreement studies). The MEPAFAR and PALMERA studies have been recently
conducted (n=176 and n=70 patients, respectively) to assess the agreement
between community pharmacy, clinic, home and ambulatory BP (ABP)
measurement methods in treated hypertensive patients. Moreover, in a
previous work we also reported that the white-coat effect in the community
pharmacy was negligible and significantly lower than that observed at the
clinical setting [7,8]. The CPBP measurement method was found to be very
reliable to confirm the presence of uncontrolled BP figures (specificity:
91.8% -using daytime ABP monitoring as reference method-), whereas
sensitivity was found to be lower: 61.0% (these results are not published
yet; articles submitted to journals). Also, measuring BP in the community
pharmacy showed a greater ability than home BP monitoring to confirm the
presence of uncontrolled BP (positive likelihood ratios: 7.4 vs. 3.0,
respectively) and was superior to the clinic BP measurement method for
detecting the presence of both uncontrolled (positive likelihood ratios:
8.5 vs. 1.7, respectively) and controlled BP (negative likelihood ratios:
0.4 vs. 0.5, respectively).
Based on the results of our studies, we believe that the CPBP
measurement method could be a valuable tool for the diagnosis of
hypertension. However, further research is needed. In order to assess the
usefulness of this method in the diagnosis of hypertension, future studies
should include patients not undergoing treatment and without hypertension.
Finally, it is important to note that a global assessment of this method
would require studies measuring the association of CPBP measurements with
cardiovascular risk and target organ damage.
References
1. Hodgkinson J, Mant J, Martin U, Guo B, Hobbs FD, Deeks JJ et al.
Relative effectiveness of clinic and home blood pressure monitoring
compared with ambulatory blood pressure monitoring in diagnosis of
hypertension: systematic review. BMJ 2011; 342: d3621.
2. Sabater-Hernandez D, de la Sierra A, Bellver-Monzo O, Divison JA,
Gorostidi M, Perseguer-Torregosa Z et al. Action guide for community
pharmacist in patients with hypertension and cardiovascular risk. A
consensus document (extended version). Ars Pharm 2011; 52: 38-58. Spanish.
3. Williams B, Poulter NR, Brown MJ, Davis M, McInnes GT, Potter JF
et al. British Hypertension Society guidelines for hypertension management
2004 (BHS-IV): summary. BMJ 2004; 328: 634-40.
4. Tsuyuki R, Campbell N. 2007 CHEP-CPhA guidelines for the
management of hypertension by pharmacists. Can Pharm J 2007; 140: 238-9.
5. Sabater-Hernandez D, Azpilicueta I, Sanchez-Villegas P, Amariles
P, Baena MI, Faus MJ. Clinical value of blood pressure measurement in the
community pharmacy. Pharm World Sci 2010; 32: 552-8.
6. Sabater-Hernandez D, Sanchez-Villegas P, Lacampa P, Artiles-
Campelo A, Jorge-Rodriguez ME, Faus MJ. Evaluation of the hypertensive
state in treated patients: selection of appropriate blood pressure
measurements per visit to the community pharmacy. Blood Press Monit 2011;
16: 103-110.
7. Sabater-Hernandez D, de la Sierra A, Sanchez-Villegas P, Baena MI,
Amariles P, Faus MJ. Magnitude of the White-Coat Effect in the Community
Pharmacy Setting: The MEPAFAR Study. Am J Hypertens [Epub 2011 Apr
21].doi: 10.1038/ajh.2011.68.
8. Sendra-Lillo J, Sabater-Hernandez D, Sendra-Ortola A, Martinez-
Martinez F. Comparison of the white-coat effect in community pharmacy
versus the physician's office: the Palmera study. Blood Press Monit 2011;
16: 62-6.
Competing interests: No competing interests
Ambulatory blood pressure monitoring for diagnosing hypertension: evidence-based medicine or evidence-based tautology ?
Establishing the diagnosis of hypertension has important
consequences: the subject is labelled as "hypertensive" and a candidate
for lifelong monitoring and treatment. One can only hope that the methods
on which this diagnosis is based are reliable (optimal sensitivity and
specificity), easy to implement on a large scale and cost-effective. There
is over a century's worth of literature on this subject, and even Riva-
Rocci, the inventor of the upper arm blood pressure cuff, mentioned the
problem of white coat hypertension. Three competing methods are currently
in use: the oldest is clinic blood pressure measurement, while ambulatory
blood pressure monitoring (ABPM) and home blood pressure measurement were
introduced more recently. Two recent articles from the same group conclude
that ABPM is the best method, followed by the British NICE guidelines. Is
it deserved?
The first article analysed data from about twenty studies including a
total of 5 683 patients and declared ABPM the winner in terms of
sensitivity and specificity. (1) The second found ABPM the most cost-
effective for diagnosing hypertension in the English primary care setting.
On the same day that the second article was published, the NICE issued
guidelines recommending ABPM as the preferred diagnostic procedure, on the
basis of the two aforementioned articles. (3) The repetition of this
statement, first in the BMJ, then in The Lancet, and finally by the NICE,
should be convincing: ABPM, and only ABPM, is the best tool for diagnosing
hypertension. This is all very well, but this conclusion seems rather
hasty to clinicians who value home measurement.
The conclusion of the first article, which compared the three
measurement methods, was: "Neither clinic nor home measurement had
sufficient sensitivity or specificity to be recommended as a single
diagnostic test. If ambulatory monitoring is taken as the reference
standard, then treatment decisions based on clinic or home blood pressure
alone might result in substantial overdiagnosis". How can three methods be
compared on an impartial basis if the starting premise is that one of them
is the gold standard? The methods section states: "We chose ambulatory
monitoring as the reference standard". Once this choice is made, to
conclude that ABPM is the reference method is a tautology, disguised as
evidence-based medicine. In the discussion section of the article, the
authors admit that they are well aware of the problem: "The findings
clearly depend on the choice of the reference standard".
Is ABPM cheaper than home measurement? The same group published a
demonstration in The Lancet, (2) with results described as "robust", that
ABPM is the more cost-effective method for diagnosing hypertension. Its
higher cost would be offset by savings generated by treating all truly
hypertensive patients and only them. We have two comments. The first is
that sensitivity analyses show that ABPM is not the most cost effective
option if "home monitoring [is] judged as effective as ambulatory
monitoring (a result disputed by recent meta-analysis)." We have just
expressed our concerns with this meta-analysis. Second, by considering
diagnosis in isolation from the patient's subsequent management, the model
disregards the benefits of home measurement during patient follow-up. (4)
If these benefits are taken into account, the cost of home measurement
should not be regarded as a diagnostic cost only, but distributed over the
whole patient's management whenever hypertension is confirmed.
The authors' conclusions that ABPM is the preferred method seem ill
supported to us. We believe it is legitimate not to write off diagnostic
home measurement as hastily as this series of three publications would
suggest. Our views on the role of the various measurement methods may be
influenced by history: clinic measurement remains the method used in
trials, at the request of drug licensing agencies, with the result that
the guidelines do not dare abandon it; solid data is available on ABPM,
and it is considered "the" gold standard for circumventing white coat and
masked hypertension; but so few studies have been conducted on the role of
home measurement in the initial diagnosis of hypertension that its
potential is not clear yet. Time will tell whether the paucity of data is
simply due to the fact that home measurement was introduced more recently
and struggles to find research funding, or whether its intrinsic qualities
and flaws imply that it should not be used as a diagnostic tool.
References
1. Hodgkinson J, Mant J, Martin U, Guo B, Hobbs FD, Deeks JJ, et al.
Relative effectiveness of clinic and home blood pressure monitoring
compared with ambulatory blood pressure monitoring in diagnosis of
hypertension: systematic review. BMJ 2011;342:d3621
2. Lovibond K, Jowett S, Barton P, Caulfield M, Heneghan C, Hobbs FR,
et al. Cost-effectiveness of options for the diagnosis of high blood
pressure pressure in primary care: a modelling study. Lancet 2011;378:1219
-30. Epub 2011 Aug 24
3. Krause T, Lovibond K, Caulfield M, McCormack T, Williams B;
Guideline Development Group. Management of hypertension: summary of NICE
guidance. BMJ 2011; 343:d4891
4. Agarwal R, Bills JE, Hecht TJ, Light RP. Role of home blood
pressure monitoring in overcoming therapeutic inertia and improving
hypertension control: a systematic review and meta-analysis. Hypertension
2011;57:29-38.
Competing interests: No competing interests