Five year prognosis in patients with angina identified in primary care: incident cohort study
BMJ 2009; 339 doi: https://doi.org/10.1136/bmj.b3058 (Published 06 August 2009) Cite this as: BMJ 2009;339:b3058
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Have I missed something here?
Buckley et al set out to characterise the risk of various cardiac
outcomes and interventions in a cohort of patients with aa diagnosis of
angina. This they achieved extremely well and in the process have provided
a useful epidemiological resource.
What they also achieved was to stick within their research objectives
and not wander off into fields beyond their scope. There may well be an
extensive evidence base relating to the role of blood viscosity (and other
risk indicators) in ischaemic heart disease but it is not relevant to the
present study, which simply describes the current situation from the
perspective of primary care.
I applaud the authors for their restraint!
Competing interests:
None declared
Competing interests: No competing interests
Greenberg's recent demonstration of the way in which citation bias
can lead to wrong conclusions seem to be exemplified by the material
published in the fields of cardiovascular and cerebrovascular disorders.
By ignoring what has been written about the role of blood viscosity in
these disorders, clinicians focus on vascular changes, rather than changes
in the physical properties of the blood,in the management of such
disorders.
The symptoms of angina are probable manifestations of impaired
capillary blood flow due to reduced red cell deformability and/or
increased blood viscosity. Such changes may be amplified by vigorous
activity or stress, but are relieved by rest. It was noted that both
smoking and age were associated with adverse outcomes, and both are
associated with increased blood viscosity. Unless the blood viscosity
problem is addressed, then it can be predicted that ischemic heart disease
will follow.
But it is irrational to use angioplasty or bypass operations in an
attempt to restore normal cardiac blood flow, without attempting to lower
blood viscosity. Buckley et al noted, "Neither of the invasive cardiac
procedures significantly reduced the risk of all cause mortality," a
conclusion which implies that the major problem was not being addressed.
The authors stated also, "To minimise adverse reactions, optimal
preventive treatments should be used in patients with angina," but made no
specific recommendations. But there are several approaches to lowering
blood viscosity which could be helpful. Cessation of smoking, dietary
modification towards a low meat and fat intake, with an increased intake
of oily fish, and regular, low intensity physical activity (such as
walking) will lower blood viscosity. As an elevated haematocrit raises
blood viscosity, if necessary this should be lowered. Increased levels of
fibrinogen is an important factor in raised blood viscosity, and if
elevated should be lowered to normal levels.
The recognition of increased blood viscosity as a causal factor in
angina means that the patient can be given some responsibility in managing
his/her health problem. In addition, significant savings could be
anticipated from the lack of use of the surgical procedures.
Competing interests:
None declared
Competing interests: No competing interests
A strange feature of this paper and the responses is that there is no
recognition of the fact that there are many reports which show that when
blood viscosity is raised by increased levels of fibrinogen, angina is
manifest. A search in PubMed for "Angina and blood viscosity" produced
more than 160 titles dating from 1967.
Given the easy availability of search engines for literature
searches, this paper could be an example of "citation bias" as reported
recently by Greenberg, where papers which are in conflict with the
opinions of the authors are simply ignored.
The situation is not improved by the observations by the authors that
aging and smoking are increased risk factors, without apparent recognition
of the fact that both factors are associated with increased blood
viscosity.
Because the problem is considered as being vascular in origin without
recognition of the importance of the physical properties of the blood, the
beneficial effects of lowering blood viscosity are neither utilised or
recognised.
For example a 2008 paper stated, "Chronic intermittent urokinase
administrations - given with the aim of achieving fibrinogenolysis of the
elevated fibrinogen concentration at a dose of 500,000 IU urokinase three
times weekly - improves the rheological parameters and achieves an
impressive decrease in symptoms."
It remains to be seen if the Greenberg finding of citation bias lead
to an editorial requirement for authors to complete a comprehensive
literature search and include a discussion of contrary opinions.
Competing interests:
None declared
Competing interests: No competing interests
Buckley et al [1] report important findings for the prognosis of
patients with incident angina in primary care. They write ‘While the
benefit associated with percutaneous transluminal coronary angioplasty in
patients with acute coronary syndromes is established, its value in
patients without these problems is less certain’.
In those patients with exertional angina, it has long been known that
prognosis for myocardial infarction and death is not improved by coronary
revascularisation, from a 2000 meta-analysis of randomised controlled
trials comparing PTCA (percutaneous trans-luminal coronary angioplasty,
balloon angioplasty alone without stenting) with medical treatment alone
[2] to the more recent COURAGE trial.[3]
The importance of revascularisation in improving symptomatic outcomes
has been shown in both meta-analyses [2] and large clinical trials.[3]
Prognostic outcomes in trials examining the impact of revascularisation in
patients with exertional, non-acute angina should include measures of
morbidity, i.e., in the study of symptomatic outcomes, quality of life or
return to work, rather than focussing on myocardial infarction, ‘MACE’ and
death. These outcomes may then reveal surprising differences - we recently
reported that South Asian patients with chronic angina were less likely to
experience long-term improvement in angina following coronary
revascularisation when compared to whites, despite a similar prognosis for
myocardial infarction and death, even after having taken into account
appropriateness for revascularisation and differences in clinical
characteristics. [4]
Patients go to doctors with symptoms. Though they may well ask ‘what
are my chances, doc’, they also want to get rid of those symptoms.
1. Buckley BS, Simpson CR, McLernon DJ, Murphy AW, Hannaford PC. Five
year prognosis in patients with angina identified in primary care:
incident cohort study. BMJ 2009;339(August 6):b3058-.
2. Bucher HC, Hengstler P, Schindler C, Guyatt GH. Percutaneous
transluminal coronary angioplasty versus medical treatment for non-acute
coronary heart disease: meta-analysis of randomised controlled trials. BMJ
2000;321(7253):73-7.
3. Boden WE, O'Rourke RA, Teo KK, Hartigan PM, Maron DJ, Kostuk WJ,
et al. Optimal Medical Therapy with or without PCI for Stable Coronary
Disease. N Engl J Med 2007(March 26, 2007):NEJMoa070829.
4. Zaman MJ, Crook AM, Junghans C, Fitzpatrick NK, Feder G, Timmis
AD, et al. Ethnic differences in long-term improvement of angina following
revascularization or medical management: a comparison between south Asians
and white Europeans. J Public Health (Oxf) 2009;31(1):168-74.
Competing interests:
None declared
Competing interests: No competing interests
Sir,
Buckley et al are to be congratulated on their study of angina
prognosis (1), perhaps finally answering this important question. However,
it is one that has a long history in primary care epidemiological
research, which we pulled together in a systematic review. (2) John Fry, a
solo GP in SE London (3-5) looked at angina prognosis 40 or more years
ago. Despite the limitations of relatively small numbers (n=268), paper
records and manual punch cards, this was a remarkable piece of work with a
high follow up rate (88%). He estimated a peak incidence aged 60-69, an
annual mortality of 4.6%, ¾ of a cardiovascular cause, a relatively worse
prognosis in younger age and men with a worse prognosis than women. Fry’s
practice was a relatively affluent one compared with many of the Scottish
practices in Buckley’s study, but even so changes in lifestyle and
treatments may be making some headway in improving prognosis of those with
angina.
Further back, some of the first descriptions of the epidemiology of
angina appear. Osler (1910) described a peak death rate in the 50-60 age
group (6). Mackenzie, originally a GP reported data in 1923 (7) which
allows us to estimate angina prognosis, although the underlying pathology
was probably different (rheumatic fever, syphilis and less
atherosclerosis). He recorded a peak death rate between 61-65 with the
majority dying within 5 years of onset, 11% within 1 year and noted the
preponderance of men among those with angina. He also describes the impact
of severity on prognosis, noting “limitation on effort is a more serious
sign” and a poorer prognosis with raised blood pressure angina.
Angina prognosis seems to be an important concept in primary care,
perhaps this is because despite all the technological changes in
cardiology, most angina diagnoses are still first made in the GP surgery,
largely on the basis of taking a good history.
Melvyn Jones
(1) Buckley BS, Simpson CR, McLernon DJ, Murphy AW, Hannaford PC.
Five year prognosis in patients with angina identified in primary care:
incident cohort study. BMJ 2009; 339:b3058.
(2) Jones M, Rait G, Falconer J, Feder G. Systematic review: prognosis of
angina in primary care. Fam Pract 2006; 23(5):520-528.
(3) Fry J. The natural history of angina in a general practice. Journal
of the Royal College of General Practitioners 1976; 26:643-646.
(4) Fry J. Angina in general practice. Lancet 1998; 1(8596):1225.
(5) Fry J. Coronary Heart disease in general practice: natural history
over twelve years (1950-1961). Proc R Soc Med 1964; 57:39-42.
(6) Osler W. The Lumelian Lectures on Angina Pectoris. Lancet 1910;
1:839.-844.
(7) MacKenzie J. Angina Pectoris. Oxford Medical Publications ( Henry
Frowde and Hodder & Stoughton); 1923.
Competing interests:
Published in this area
Competing interests: No competing interests
Re: Re. angina and viscosity
According to Jonathan Belsey, "Buckley et al set out to characterise
the risk of various cardiac outcomes and interventions in patients with a
diagnosis of angina." The objective of the study was, "To ascertain the
risk of acute myocardial infarction etc....among patients with newly
diagnosed angina, over 5 years."
But how could they, "...ascertain the risk," if the major risk
factor, i.e. increased blood viscosity was ignored ? After all, smoking
was shown to have an adverse effect. Does Jonathan Belsey not accept the
evidence which shows that smoking increases blood viscosity ?
Furthermore, does he believe that GPs would not be interested to
learn WHY neither angioplasty or bypass operations greatly increase
survival in those with angina ? Surely the possibility that angina
patients can contribute to the control of their health problem by making
lifestyle changes would be of interest to those working in the field of
primary care.
Competing interests:
None declared
Competing interests: No competing interests