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| Journal of the New Zealand Medical Association,
31-March-2006, Vol 119 No 1231
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Management of risk factors: a survey of New Zealand vascular
surgeons
Heidi Su, Malcolm Gordon, Justin Roake, David Lewis
Peripheral occlusive arterial disease (POAD) has been
estimated to affect between 5% and 20% of the population depending on age and
symptoms.1,2 No data are available for the scale of the problem in New Zealand
(NZ), but the prevalence is probably similar to other Western countries. For
patients with intermittent claudication (IC), the risk of limb loss is
relatively small (1–2% a year), however patients with POAD are at
significant risk of cardiovascular events, and patients with IC have 2–4
times greater mortality than patients without POAD.3 Best medical therapy (BMT)
regarding risk factor modification can make a significant difference to outcome
in patients with atherosclerotic disease.4
Despite having similar risks of mortality and morbidity,
studies had shown that patients with POAD often received less risk-factor
modification than patients with coronary disease.5,6 Risk factors are often
reported to be poorly documented and poorly treated in both primary and tertiary
care.7,8
There is debate regarding who should be responsible for risk
factor management in patients with POAD. Some vascular surgeons suggest that
they are well placed to provide such a service while physicians disagree with
this sentiment.9,10 In recent years, the subspeciality of vascular medicine or
angiology has emerged in Europe and North America. These vascular physicians
focus on providing medical therapy for patients with POAD which usually revolves
around risk factor management.
The aim of this study was to document the opinion of New
Zealand vascular surgeons regarding risk factor management in patients with
POAD.
MethodsA list of practicing vascular surgeons and their
contact details was obtained from the New Zealand Vascular Society (NZVS). In
February 2005, a questionnaire (Appendix 1) was
emailed to 42 vascular surgeons. Surgeons were also given the option of printing
the survey and returning it by post. If no email address was available from the
NZVS, District Health Boards were contacted regarding this information and, if
no email address was registered, a copy of the survey was faxed to the surgeon.
If no response was received after 3 weeks, then a second electronic survey was
emailed. Three weeks following the second email, a postal survey with a
reply-paid envelope was sent to non-responders.
The survey consisted of seven sections of questions
with a tick-box or yes/no format. Surgeons were asked to identify the modifiable
risk factors they consider as significant for peripheral vascular disease and
questioned if they routinely check these risk factors. Surgeons were offered a
choice to indicate which speciality they considered most appropriate for
managing each risk factor for vascular disease. The surgeons were advised that
they could tick as many boxes as they thought appropriate for each
question.
Responding surgeons were also provided with a space on
the questionnaire to give open comments.
ResultsReplies were received from 35 of the 42 New Zealand vascular
surgeons (83%). Sixteen (46%) of the responses were returned by email. Eleven
(31%) of the replies were received within the first 3 weeks, 8 (23%) were
received after the second email, and 16 (46%) were received after the postal
survey.
The responses to questions relating to which risk factors
were considered important and which risk factors were routinely checked by the
vascular team are shown in Figures 1 and 2. No vascular surgeons check
homocysteine level but 15 (43%) consider hyperhomocysteinaemia to be a risk
factor for vascular disease.
Table 1. Who do you think should initiate therapy (for
each risk factor)? (%)
The majority of vascular surgeons believed that GPs should
play a central role in the management of risk factors but many also believe that
the vascular team and/or specialist physicians should play a role in risk factor
modification. Opinion regarding who should initiate treatment of risk factors is
summarised in Table 1.
Figure 1. What do you consider to be significant
modifiable risk factors for peripheral vascular disease?
 Figure 2. Do you routinely check (each of these risk
factors)?
 With regard to smoking cessation programmes, only 18 (51%)
of the vascular surgeons had dedicated smoking cessation facilities in their
hospital.
The vascular surgeons were asked to choose one or more of
the antihypertensives that they prefer to be used for peripheral vascular
disease patients. The results are shown in Figure 3. The majority of surgeons
(63%) did not express a preference.
Figure 3. Do you have a preference for which
antihypertensive therapy is initiated?
 Aspirin was the antiplatelet therapy of choice for 29 (83%)
of the vascular surgeons and the preferred dose varied between 50 mg and 300 mg
a day, with most recommending a dose of 150 mg or less.
Some vascular surgeons commented that “ideal
practice” is often difficult to implement in a busy outpatient setting,
and that general practitioners (GP) may be better placed to review treatments
for side-effects and interactions. Surgeons also commented that GPs are better
able to monitor progress and coordinate referral to specialist physicians where
necessary. Although access to GPs is generally easier than to vascular surgeons,
some surgeons commented that in lower socioeconomic areas patients often see a
different GP at each attendance and therefore it may be more appropriate to
monitor risk factor modification as a hospital outpatient. Many surgeons stated
that they consider risk factor management to be a multidisciplinary
problem.
DiscussionThis study showed that New Zealand vascular surgeons
generally recognise the significance of modifiable risk factors in patients with
POAD but frequently do not test for the presence of these factors in the
outpatient setting. Many surgeons suggested in the survey that, due to lack of
time during outpatient clinics, GPs should conduct risk factor assessment prior
to consultation with a vascular specialist. A majority of vascular surgeons in
New Zealand also consider that GPs should be pivotal in risk factor
management.
Although the current survey had a small number of subjects
(n=42), the high response rate of 83% is probably a good reflection of current
practice in New Zealand. It may also reflect the interest of New Zealand
vascular surgeons in this complex topic. The initial response rate to the
electronic surveys was relatively low at 26% after the first email and 45% after
the second email. This response rate is, however, similar to other studies using
electronic surveys.11,12
By using electronic surveys alone there is a risk of bias in
selecting the group who access emails frequently and are possibly more computer
literate. We compensated for this potential bias by sending out postal surveys
to outstanding replies after the second email. The design of the questionnaire
was deliberately kept simple to maximise the response rate but did restrict
respondees regarding the scope of their answers. A section for
“open” comments was included in an attempt to compensate for this
potential bias, and many of these comments have been included in this
manuscript. This study assumed that all current New Zealand vascular surgeons
are members of the NZVS and therefore may have missed a small number of surgeons
who treat patients with POAD in New Zealand.
Smoking has long been established as a strong risk factor
for atherosclerosis,3 as agreed by 97% of vascular surgeons in our study.
Smoking cessation can significantly reduce this risk4 but it has been reported
that simple advice to quit smoking only has a small effect on cessation rate.13
Studies on smoking cessation clinics showed that individualised treatment using
counselling and nicotine replacement therapies produced a higher rate of
abstinence.14 In our study, only 51% of the vascular surgeons have dedicated,
hospital-based smoking cessation clinics which probably reflects a lack of
resources.
Hypertension is a major risk factor for atherosclerotic
disease, and the risk of morbidity and mortality can be reduced by lowering
blood pressure . Most (89%) of the vascular surgeons in our study recognised
this risk factor but the majority (63%) had no preference regarding the choice
of antihypertensive medication used in their patients.
The Heart Outcomes Prevention Evaluation (HOPE) study
demonstrated the benefit of ACE-inhibitors with regard to reduction in
cardiovascular risk regardless of the patients blood pressure.17 ACE-inhibitors
were the preferred antihypertensive for 23% of vascular surgeons in our study
and may reflect recent publication in vascular surgical literature . It is
important to monitor renal function in patients prescribed ACE-inhibitors. The
majority of surgeons considered that GPs should manage hypertension while only
3% thought that this should be the responsibility of the vascular team.
Two vascular surgeons commented that β-blockers should
not be used in patients with POAD. Although β-blockers may exacerbate
symptoms of POAD they are not absolutely contraindicated and in some patient
subgroups the cardiac benefit of β-blockade may dictate prescription of
this class of medication.19,20
Dyslipidaemias lead to increased risk of cardiovascular
events and prescription of lipid lowering therapy has been shown reduce this
risk.21–24 The recently published Heart Protection Study has provided the
strongest evidence to date of the benefit of lipid lowering therapy in patients
with POAD. It reported that statins were of benefit to patients with POAD, even
in those patients with a “normal” cholesterol level . Guidelines for
the prescription of statins in New Zealand may require updating to allow this
benefit to a potentially vulnerable group of patients with POAD. Twenty percent
of those responding thought that the vascular team should manage lipid lowering
therapy but again, the majority nominated the GP.
Diabetes mellitus is another major risk factor for POAD and
may increase the risk of progression from claudication to critical limb
ischaemia.26 It has been reported that intensive control of blood glucose may
decrease risk of microvascular complications, but not macrovascular disease.27
Nearly 60% of vascular surgeons stated that they check for diabetes mellitus but
the vast majority thought that diabetes is best managed by GPs or physicians
with an interest in this disease.
An increased level of serum homocysteine is an independent
risk factor for atherosclerosis. Studies have reported that mild
hyperhomocysteinaemia occurs in 5–7% of the general population and in
27–50% of patients with symptomatic atherosclerotic disease.28 Only 43% of
the vascular surgeons in our study stated that they considered
hyperhomocysteinaemia to be a significant risk factor, and none of them check
serum homocysteine levels in their patients. This latter result may reflect the
current lack evidence that cardiovascular risk can be reduced by lowering the
homocysteine level.
Antiplatelet therapy has been shown to significantly reduce
cardiovascular events in “at risk” patients. No optimal dose of
aspirin has been determined but a low dose (75–150 mg/day) is suggested by
the Antiplatelet Trialists’ Collaboration.29 These recommendations were
acknowledged by most of the vascular surgeons in our study. The recommendation
for low-dose aspirin is based on maximising the benefit of the antiplatelet
effect of aspirin while minimising gastrointestinal side effects.
The CAPRIE Trial found that the thienopyridine, clopidogrel
is slightly more effective than aspirin at reducing recurrent ischaemic events30
but given the cost involved, it is generally accepted that aspirin is the
first-line antiplatelet agent except in special circumstances. The concept of
aspirin resistance has recently questioned whether patients are adequately
protected from ischaemic events by aspirin monotherapy but much more work is
needed on this subject before a change in current practice can be
suggested.31
European vascular surgeons have argued that they should
manage all aspects of POAD, including risk factors for atherosclerosis, since
they are aware of the pathogenesis of atherosclerosis as well as the molecular
dysfunction and the haemodynamic consequences of this disease. The additional
task of risk factor management and time involved is suggested to be minor.9
From the angiologist point of view, patients with POAD
should be managed by a clinician trained in several different fields of
medicine, because of the (often multiple) comorbidities present in these
patients.10
The New Zealand vascular surgeons in our study expressed the
opinion that it can be difficult to take on this extra workload given the
limited time available in surgical outpatient clinics. This is, however, an
opportunity lost with regard to screening for risk factors. GPs may be better
placed to review the success or side effects of treatments but may also be less
aware of the importance of treating risk factors aggressively.
With an aging population and the increasing expectations of
the general public regarding the provision of healthcare, risk-factor
modification and patient education is already at the forefront of the management
of patients with POAD. Regardless of who is the responsible clinician, it is
important to ensure best medical therapy for these patients and this will
frequently require a multidisciplinary approach.
In summary, risk-factor modification for patients with POAD
is an essential facet of their medical management and New Zealand vascular
surgeons generally recognise the importance of these risk factors. There is
currently lack of consensus regarding who is best placed to implement or oversee
risk factor modification for patients with POAD. Our study suggests that the
opinion of New Zealand vascular surgeons differs from vascular surgeons in
Europe. Improving doctor and patient education will undoubtedly influence this
consensus.
Whatever the responsible clinician calls himself/herself,
our current focus should be on treating these risk factors by working together
and seeking expert advice when necessary.
Author information:
Heidi Y Su, House Officer; Malcolm Gordon, Justin Roake, David Lewis, Consultant
Vascular Surgeons; Christchurch Vascular Group, Department of Surgery,
Christchurch Hospital, Christchurch
Acknowledgements: We
thank the New Zealand Vascular Society as well as all the New Zealand Vascular
Surgeons for their time and assistance with this survey.
Correspondence: Mr
DR Lewis, Consultant Surgeon, Christchurch Hospital, Private Bag 4710,
Christchurch. Fax (03) 364 0352; email david.lewis@cdhb.govt.nz
References:
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