From the Department of Geriatric Medicine, Newham General Hospital and St
Andrew's Hospital (S.L.), and Department of Health Economics, City
University (A.M.), London, UK.
Correspondence to Dr Sara Lightowlers, Department of Geriatric Medicine, St Andrews's Hospital, Devas St, London E3 3NT, UK.
Methods—We calculated the incremental costs per life-year gained
for 4 base cases using efficacy data from the Boston Area
Anticoagulation Trial for Atrial Fibrillation, the
meta-analysis of the 5 nonrheumatic atrial fibrillation trials,
cost data from a district general hospital, and review of the
literature.
Results—The cost per life-year gained free from stroke over 10
years ranged from -£400.45 (ie, a resource saving achieved for each
life-year gained free from stroke) to £13 221.29. The results were
most sensitive to alteration in the frequency of anticoagulation
monitoring.
Conclusions—For medical and economic reasons, anticoagulation
treatment in the prevention of ischemic stroke is justified.
Although older patients are more at risk of adverse events,
anticoagulation is more cost-effective in this group.
There is no debate regarding the clinical effectiveness of
anticoagulation with warfarin in decreasing stroke incidence. However,
there is some concern about the incidence of adverse events,
particularly in the very elderly (aged >75 years). The 5 trials did
not show a statistically significant increase in the number of major
hemorrhagic events, but there is debate regarding how closely a
clinical trial, which enforces strict entry criteria, reflects routine
clinical practice. A later trial (Stroke Prevention in Atrial
Fibrillation [SPAF] II), which included a larger subgroup of very
elderly patients, showed an increasing tendency to adverse events with
increasing age.7
Because stroke is the third most common cause of death in most
developed countries and one of the most common causes of adult physical
disability, the potential benefits of preventing strokes are great.
Thus, the economic question is as follows: Given the cost of treating
adverse events, is treatment with anticoagulants in NRAF
cost-effective? This issue is of greater importance in the very
elderly, in whom the incidence of adverse events would appear to be
greater. To address this issue further, a cost-effectiveness
analysis was performed with data from the Boston Area
Anticoagulation Trial for Atrial Fibrillation (BAATAF) and the
meta-analysis of the 5 NRAF trials.
Principal Outcome
The costs of the warfarin group were calculated as the costs incurred
by treatment with warfarin, the cost of treatment of the side effects
of warfarin (bleeding events), and the cost of treatment of strokes
that occurred. The costs of the control group were the costs of
treatment of bleeding events and the cost of treatment of stroke. The
measure of effectiveness, life-years gained free from stroke, was
obtained from BAATAF and the meta-analysis data.
Life-Years Gained
Four base cases were examined: cases 1 and 2 with BAATAF data and cases
3 and 4 with the meta-analysis data. In case 1, the
within-period hazard rates remained constant from the end of the
fourth year to the 10th year in both treatment groups. In case 2, the
mean of the within-period hazard rates from years 1 to 4 was used from
years 5 to 10 in both treatment groups. In case 3, hazard rates for
stroke of 0.045 for the control group and 0.015 for the warfarin group
were used. These are the reported hazard rates for the whole of each
treatment group from the meta-analysis data. In case 4, hazard
rates for stroke of 0.081 for the control group and 0.012 for the
warfarin group were used, which were the reported hazard rates for the
group aged >75 years in the meta-analysis data.
The BAATAF was a small trial (420 subjects), and there were very few
stroke events over the follow-up period of the trial; therefore, the
hazard rates calculated were imprecise estimates of the true hazard
functions. The extrapolated hazard rates were calculated by 2 different
methods because the within-period hazard rate for year 4 was greater in
the warfarin group than in the control group, which would not be
expected and reflects that the trial was small. However, BAATAF data
were used because there was some information available on individual
subjects in the trial.
The meta-analysis data were used for cases 3 and 4. There was
less information from the meta-analysis on individual cases,
but because there was a larger number of subjects (3691), hazard rates
were likely to be more accurate, and the effects of treatment on
subgroups of patients could be analyzed (in this case the group
aged >75 years).
Life-years gained were then estimated as the difference between the
extrapolated cumulative survival curves for the warfarin treatment
group and the no-treatment group in the 4 different base cases and were
then used to derive the cost per life-year gained ratios.
Cost Estimates
Cost of Stroke
In the BAATAF, there were a total of 15 strokes (the warfarin and
no-treatment groups) over the follow-up period: 8 (53.3%) were of mild
to moderate severity, 6 (40%) were severe, and 1 (6.7%) was fatal
within 3 months of follow-up. The mortality of 6.7% at 3 months from
stroke was not representative of data from
epidemiological studies. In the OCSP, of those subjects with
ischemic stroke, the 30-day mortality was 10% as opposed to
16% in the Rochester Study and 15% in the Framingham Study.
In the OCSP, the 1-year mortality from stroke was 31%. The annual risk
of death after the first year was 9.1% up to 5 years.
In the South of England Study (which only examined patients aged <75
years), 71% were admitted to the hospital after a stroke. This figure
was only 54% in the OCSP. Very few of the patients who were not
admitted to the hospital received investigation or treatment for
stroke.9
According to the Royal College of Physicians report, 20% of those who
initially survive from stroke never improve sufficiently to return home
and are discharged to residential or nursing homes or to hospital
continuing care. Thirty-three percent of survivors return to a
restricted life at home, and the rest make a good functional recovery.
Figure 1
From the model of admission and survival after stroke, it was
determined that 6 different pathways of stroke outcome and management
exist: the patient is (1) admitted to the hospital and discharged to
the community; (2) admitted to the hospital and discharged to hospital
continuing care; (3) admitted to the hospital and dies in the hospital;
(4) not admitted to the hospital and remains in the community; (5) not
admitted to the hospital but eventually admitted to hospital continuing
care; or (6) not admitted to the hospital and dies in the
community.
The costs for each pathway were determined over a 10-year period, and
thus the average cost of stroke treatment could be calculated.
It was determined that the unit costs described in Table 1
Cost of Bleeding Events
Sensitivity Analysis
Monitoring of anticoagulation every 6 weeks was considered to be a
closer reflection of routine practice. Length of stay was varied over a
range from review of the literature. No data were available on patients
discharged to hospital continuing care beds, but assumptions were
varied over a feasible range. Variations in cost data for bed-days were
taken from review of the literature. The incidence of bleeding events
was varied with the use of data from the SPAF II trial, which was a
follow-up study of SPAF I, which included a larger subgroup of patients
aged >75 years.7
Costs
Stroke
Bleeding Events
Cost-Effectiveness Ratios
Sensitivity Analysis
The results were explored with the use of sensitivity analysis.
The results were sensitive to reducing the frequency of anticoagulation
monitoring. In the BAATAF, anticoagulation was monitored every 3 weeks,
which does not accurately reflect clinical practice. In the sensitivity
analysis, monitoring every 6 weeks was assumed, and
anticoagulation with warfarin was found to be more cost-effective, so
that in base case 3 there was a saving of £774.98 per life-year gained
free from stroke. Of the variables that affected the cost of
stroke, which were varied over a range from review of the literature,
reducing the length of stay to 18.5 days and reducing the number of
patients who went into hospital continuing care beds resulted in a net
cost of anticoagulation in base case 4. There is a trend to discharge
patients from the hospital earlier. However, these data were from a
study that examined a population of stroke patients aged<75 years,
which may partly account for much shorter lengths of stay. If patients
were discharged earlier into the community, one might expect that they
would need to receive rehabilitation at home (which did not appear to
be the case in this study), since recovery from stroke occurs for up to
6 months. This would of course increase the cost of community medical
treatment of stroke. There are certainly examples of community-based
treatment of stroke that have not been found to be cheaper than
hospital-based treatment. There has been a decline in discharge to
NHS-funded continuing care, although health authorities do have a
statutory obligation to provide continuing care beds.
Base case 4 used data on the group aged >75 years from the
meta-analysis. Anticoagulation of this group would appear to be
the most cost-effective. Even when the bleeding event rate was
increased to that found in the SPAF II trial, which was significantly
greater than the bleeding event rate in the other trials, there was
still a monetary saving to be derived from anticoagulation with
warfarin, which is probably a reflection of the greater incidence of
stroke in this age group. It is well recognized that the monitoring
patients receive as part of a clinical trial differs significantly from
routine clinical practice, which would account for the small number of
bleeding events in the BAATAF cohort and the meta-analysis of
the 5 nonrheumatic atrial fibrillation trials. The bleeding event rate
in routine clinical practice is probably even higher than in SPAF II.
However, in a group of subjects who are at high risk of stroke but are
also at high risk of bleeding, there is still a cost saving. When we
examine the data for the group aged <65 years who had no risk factors
for stroke other than NRAF, the group actually derived no therapeutic
benefit from anticoagulation. Therefore, it would not be cost-effective
for them to undergo anticoagulation.
It should be noted that this study does not include data from secondary
prevention trials, in which the effectiveness of anticoagulation is
even more impressive in absolute terms in the prevention of further
stroke and in which there is a statistically significant increase in
bleeding events (but not major bleeding
events).11 These data were not included because
the model for admission and survival after stroke was based on
epidemiological data investigating outcome from first-ever stroke.
These findings are consistent with other economic
analyses. In a Swedish study, investigators concluded that
prophylactic treatment with anticoagulants prevents strokes
and saves money if the bleeding complication rate is
low.12 In a US cost-utility study, investigators
found that in those subjects who were at high risk of stroke (ie, 2
other risk factors for stroke as identified in the
meta-analysis of the NRAF trials), there was a cost saving per
quality-adjusted life-year gained and only a minimal health advantage
at high cost in a low-risk group (ie, no other risk factors for
stroke).13 They also explored the effects of age
by altering the stroke and major hemorrhage rates and agreed
with the findings in this study that warfarin therapy is less expensive
in older patients.
The present analysis has several limitations. The
perspective of this analysis was that of the third-party payer,
in this case the NHS. From the studies reviewed on the lifetime cost of
stroke, there is some indication that a large proportion of the cost of
stroke is in the longer-term continuing care of a disabled adult in the
community, either because of the cost of social input at home or
because of residential or nursing home
care.14 15 16 In this study the only continuing
care that was included was medical, since this is the only cost that is
incurred by the NHS. Residential and nursing home costs are paid for
personally or by the Department of Social Services. Another limitation
of the study was that indirect costs were not included in the
analysis. If the data had been analyzed from the
societal perspective and indirect costs had been included, the cost of
stroke would have been greater, and thus treatment with anticoagulants
would have been more cost effective.
A model had to be constructed for the routine care of stroke patients
with the use of professional opinions from a district general hospital
and data on admission rates, lengths of stay, and numbers discharged to
hospital continuing care from review of the literature. In the future a
more accurate description of routine stroke care will be available
because currently audits are being performed to investigate and attempt
to improve the routine care of stroke patients. The model has its
limitations. However, the results of the sensitivity analysis
seem to indicate that even when the data in the model were varied over
a wide range from review of the literature, there was little effect on
the cost-effectiveness of anticoagulation.
The effects of rare events (such as systemic embolism) or relatively
insignificant events (minor hemorrhage) were not considered but
were not likely to affect the cost-effectiveness ratio significantly
because even major hemorrhage had little effect on the
analysis. Mortality from events other than stroke was not
considered in the analysis. This is much more likely to have an
effect on the analysis because 37 patients died during the
BAATAF (11 deaths in the warfarin group and 26 in the control group, a
significant difference).
There were also problems with the survival analysis from the
BAATAF data. There were very few stroke events over the follow-up
period of the trial, so that the hazard rates are imprecisely
estimated. However, the analysis of the 4 base cases probably
covers the range of effectiveness seen in clinical practice.
The unit cost data were mainly collected from a district general
hospital. However, even when costs were varied in the sensitivity
analysis from review of the literature, there was little effect
on the cost-effectiveness of anticoagulation. It should also be
remembered, however, that prices do not always reflect costs because of
imperfect information in the healthcare market.
In summary, anticoagulation in the primary prevention of
ischemic stroke is cost-effective in patients aged >65 years.
Although subjects in the group aged >75 years are more at risk of
adverse events while undergoing anticoagulation, anticoagulation is
more cost-effective in this group, presumably because the subjects have
a higher incidence of stroke.
Received April 30, 1998;
revision received June 5, 1998;
accepted June 8, 1998.
2.
Petersen P, Boysen G, Godtfredsen J, Andersen ED,
Andersen B. Placebo controlled randomised trial of warfarin and aspirin
for prevention of thromboembolic complications in chronic atrial
fibrillation. Lancet. 1989;1:175–179.[Medline]
[Order article via Infotrieve]
3.
Veterans Affairs Stroke Prevention in Nonrheumatic
Atrial Fibrillation Investigators. Warfarin in the prevention of stroke
associated with nonrheumatic atrial fibrillation. N Engl
J Med. 1992;327:1406–1412.[Abstract]
4.
Stroke Prevention in Atrial Fibrillation
Investigators. Stroke Prevention in Atrial Fibrillation Study.
Circulation. 1991;84:527–539.
5.
Connolly SJ, Laupacis A, Gent M, Roberts RS, Cairns
JA, Joyner C, for the CAFA Study Coinvestigators. Canadian Atrial
Fibrillation Anticoagulation Study. J Am Coll Cardiol. 1991;18:349–355.[Abstract]
6.
Atrial Fibrillation Investigators. Risk factors for
stroke and efficacy of antithrombotic therapy in atrial fibrillation:
analysis of pooled data from five randomised controlled trials.
Arch Intern Med. 1994;154:1449–1457.
7.
Stroke Prevention in Atrial Fibrillation
Investigators. Warfarin versus aspirin for prevention of
thromboembolism in atrial fibrillation: Stroke Prevention in Atrial
Fibrillation II study. Lancet. 1994;343:687–691.[Medline]
[Order article via Infotrieve]
8.
Bamford J, Sandercock P, Dennis M, Burn J, Warlow C. A
prospective study of acute cerebrovascular disease in the community:
the Oxfordshire Community Stroke Project 1981–1986, II: incidence,
case fatality rates and overall outcome at 1 year of cerebral
infarction, primary intracerebral haemorrhage
and subarachnoid haemorrhage. J Neurol
Neurosurg Psychiatry. 1990;53:16–22.
9.
Wolfe CDA, Taub NA, Bryan S, Beech R, Warburton F,
Burney PGJ. Variations in the incidence, management and outcome of
stroke in residents under the age of 75 in two health districts of
Southern England. J Public Health Med. 1995;17:441–418.
10.
Stroke: Towards Better Management. London,
UK: Royal College of Physicians of London; 1989.
11.
EAFT Study Group. Secondary prevention in nonrheumatic
atrial fibrillation after transient ischaemic attack or minor stroke.
Lancet. 1993;342:1255–1262.[Medline]
[Order article via Infotrieve]
12.
Gustafsson C, Asplund K, Britton M, Norwing B, Olsson
B, Marke L. Cost effectiveness of primary stroke prevention in atrial
fibrillation: Swedish national perspective. BMJ. 1992;305:1457–1459.
13.
Gage BF, Cardinalli AB, Albers GW, Owens DK. Cost
effectiveness of warfarin and aspirin for prophylaxis of stroke in
patients with nonvalvular atrial fibrillation. JAMA. 1995;274:1839–1844.
14.
Bergman L, van der Meulaen JHP, Limburg M,
Habbema JDF. Costs of medical care after first ever stroke in the
Netherlands. Stroke. 1995;26:1830–1836.
15.
Taylor TN, Davis PH, Torner JC, Holmes J, Meyer JW,
Jacobson MF. Lifetime cost of stroke in the United States.
Stroke. 1996;27:1459–1465.
16.
Scott WG, Scott H. Ischaemic stroke in New Zealand: an
economic study. N Z Med J. 1994;107:443–446.[Medline]
[Order article via Infotrieve]
© 1998 American Heart Association, Inc.
Original Contributions
Cost-Effectiveness of Anticoagulation in Nonrheumatic Atrial Fibrillation in the Primary Prevention of Ischemic Stroke
Abstract
Top
Abstract
Introduction
Subjects and Methods
Results
Discussion
References
Background and Purpose—A number
of clinical trials have shown the value of anticoagulating patients
with nonrheumatic atrial fibrillation to prevent ischemic
stroke. The purpose of this study was to assess the cost-effectiveness
of anticoagulation in nonrheumatic atrial fibrillation with particular
reference to the very elderly (aged >75 years) who have a higher
incidence of bleeding events while undergoing anticoagulation.
Key Words: atrial fibrillation • cost-benefit analysis • stroke
Introduction
Top
Abstract
Introduction
Subjects and Methods
Results
Discussion
References
Anumber of clinical trials have shown the value of
anticoagulating patients with nonrheumatic atrial fibrillation (NRAF)
to prevent occurrence of ischemic
stroke.1 2 3 4 5 The 5 trials all had a similar broad
approach. Patients with NRAF who had no contraindications to
anticoagulation were randomized to treatment with warfarin or treatment
with placebo or no treatment. In 2 of the trials there was also a group
randomized to treatment with aspirin. The mean age of the subjects was
69 years. All 5 trials showed a statistically significant decrease in
the number of strokes in those treated with warfarin. A
meta-analysis of these 5 trials revealed the same trends,
obtained a more precise estimate of efficacy and risk, and showed an
increased risk of stroke with increasing
age.6
Subjects and Methods
Top
Abstract
Introduction
Subjects and Methods
Results
Discussion
References
Cost-effectiveness analysis is a common method of
evaluating the resource costs incurred in achieving a predefined
clinical outcome. Although a number of perspectives may be adopted,
this evaluation has considered the view of the third-party payer (the
National Health Service [NHS]) and has calculated only direct
costs.
The principal outcome measure was the incremental cost per
life-year gained free from stroke. This was derived as follows: (total
cost of treatment with warfarin-total cost of no treatment)/life-years
gained free from stroke.
Reported information on cumulative survival rates for the
warfarin and no-treatment groups was taken from the BAATAF (terminated
after 4 years of follow-up). The underlying hazard rate for each group
was calculated from this information. The reported hazard rates from
the meta-analysis data were also used. The estimated
within-trial hazard rates were then used to extrapolate the cumulative
survival curves beyond the end of the clinical trial, so that the
life-years gained free from stroke over a 10-year period were
calculated, a realistic life expectancy for the meta-analysis–
and BAATAF-type populations. External validation of this posttrial
modeling is difficult because of lack of natural history studies in
patients of this type.
Cost of Anticoagulation
The cost of anticoagulation was calculated during a 10-year
period from the cost of warfarin and the cost of monitoring
anticoagulation every 3 weeks (the intensity of monitoring in the
BAATAF). All of the costs of anticoagulation are for a UK-based
anticoagulation clinic, where services are already well
established.
The cost of stroke is complex. A model for routine management of
stroke patients was devised. Data on severity of and fatality from
stroke in the first 3 months were derived from the BAATAF.
Epidemiological data for the longer-term outcome from stroke were taken
from the Oxfordshire Community Stroke Project
(OCSP).8 Epidemiological data from the South of
England Study, the OCSP, and the Royal College of Physicians report on
stroke were used to determine the probabilities of patients being
admitted to the hospital after a stroke and the probability of being
discharged to the community or to hospital continuing
care.9 10 Treatment received while in the
hospital or at home and length of stay were modeled from the Royal
College of Physicians report, the South of England Study, and data from
a district general hospital. 
shows the probability of being
admitted to the hospital after a stroke, the probability of discharge
to the community or hospital continuing care, and the probability of
survival from years 1 to 10.
View larger version (28K):
[in a new window]
Figure 1. Admission and survival after stroke. HCC indicates
hospital continuing care. and marked with an asterisk were
needed to calculate the cost of stroke. The unit costs were taken from
literature review and data from a district general hospital. Any data
that were not published in 1997 were multiplied by the gross domestic
product deflator at market prices with figures from the treasury
for June 1997. All costs were discounted at the recommended UK treasury
rate of 6% to convert to net present value.
View this table:
[in a new window]
Table 1. Unit Cost
Data
It was also necessary to model the management of bleeding
events. Data from BAATAF were used for the number, type, and severity
of bleeding events. The treatment of major bleeding events was modeled
from review of the literature and data from a district general
hospital. There were 4 major bleeding events in the warfarin group and
2 in the no-treatment group in the follow-up period of the BAATAF. It
was assumed that there was 1 bleeding event per year in the warfarin
group and 0.5 event per year in the no-treatment group. Figure 2 shows the probability of each type of
major bleeding event in the trial. The costs for each type of bleeding
event were determined, and thus the average cost of bleeding event
treatment could be calculated. The unit costs were taken from review of
the literature and a district general hospital and are shown in Table 1
. All costs were discounted to net present value.
View larger version (28K):
[in a new window]
Figure 2. Probability of different bleeding events from
BAATAF.
Given that the basic analysis adopts a modeling
approach, it is sensible to apply a sensitivity analysis to
judge how robust the results are to assumptions made. The following
data were subjected to sensitivity analysis: (1) cost of
monitoring anticoagulation less frequently (every 6 weeks); (2) length
of stay for stroke; (3) percentage of patients admitted to the hospital
after a stroke; (4) percentage of patients discharged to hospital
continuing care; (5) unit costs for hospital bed-days; and (6)
incidence of bleeding events in base case 4.
Results
Top
Abstract
Introduction
Subjects and Methods
Results
Discussion
References
Life-Years Gained
The calculated life-years gained free from stroke over a 10-year
period for the 4 base cases are shown in Table 2. The fewest life-years free from stroke
were gained in base case 1. This reflects that the survival
analysis data were probably inaccurate because so few subjects
had strokes in the follow-up period of the trial, so that the estimated
stroke rate (hazard rate) for the warfarin group from years 5 to 10 was
greater than in the control group. In case 2, because the mean of the
first 4-year hazard rate was used, more life-years were gained. In case
3 the hazard rates from the meta-analysis were used to
calculate the life-years gained free from stroke. More life-years were
gained in base case 3 than when the BAATAF data were used, and this may
be a more accurate reflection of the true state because the result was
derived from examining a larger group of subjects. The most life-years
were gained in base case 4, reflecting the higher incidence of stroke
in this group.
View this table:
[in a new window]
Table 2. Life-Years Gained Free From Stroke Over a
10-Year Period
Anticoagulation
The costs of anticoagulation of 1 subject for 1 year with
anticoagulation checks every 3 weeks (the frequency of monitoring in
the BAATAF cohort) was £610.06. Therefore, the discounted cost of
anticoagulation of 1 subject for 10 years was £4759.56.
The discounted total average cost for treatment of a stroke over a
10-year period was £17 819.58. We used the survival analysis
data from the 4 base cases to estimate the expected number of strokes
in each case. Table 3 shows the
discounted cost of stroke treatment over 10 years in each of the 4 base
cases.
View this table:
[in a new window]
Table 3. Discounted Cost of Stroke Treatment Over 10 Years in
the 4 Base Cases
The average cost of a bleeding event was calculated as £2064.12.
If we assumed a constant rate of bleeding events throughout the 10
years of 0.5 event per year in the control group and 1 event per year
in the warfarin group, the discounted cost of bleeding events over 10
years was £8051.93 in the control group and £16 103.86 for the
warfarin group.
The cost-effectiveness ratios derived from attaching the
incremental costs to the increases in life expectancy free from stroke
are shown in Table 4. The discounted
costs per life-years gained free from stroke range from -£287.20 in
base case 4 to £10 437.43 in base case 1, so that in base case 4
there is actually a resource saving arising from lengthening life
expectancy in this patient group. If benefits are also discounted, the
range of costs per life-year gained free from stroke are -£400.45 to
£13 221.29.
View this table:
[in a new window]
Table 4. Cost-Effectiveness
Ratios
The results of the sensitivity analysis are shown in Table 5. The results of the cost-effectiveness
analysis were most sensitive to alteration in the frequency of
monitoring of anticoagulation. When length of stay was reduced to 18.5
days (data from the South of England Study), there was a net cost
attributable to anticoagulation in base case 4 compared with a cost
saving. When the frequency of bleeding events was increased to the
level found in the SPAF II Trial, there was still a cost saving in base
case 4.
View this table:
[in a new window]
Table 5. Sensitivity Analysis Showing Cost-Effectiveness
Ratios (Discounted Costs and
Benefits)
Discussion
Top
Abstract
Introduction
Subjects and Methods
Results
Discussion
References
The cost per life-year gained free from stroke with data from the
BAATAF and the meta-analysis varied from £1751.05 in base case
3 to £13 221.29 in base case 1. Base case 4 attempted to examine a
specific subgroup of patients (ie, the group aged >75 years) from the
meta-analysis and resulted in a cost-effectiveness ratio of
-£400.45 per life-year gained free from stroke. In relation to other
similar healthcare interventions, the cost is moderate; for example,
estimates of the cost of screening for hypertension are on the order of
£6000 to £30 000 per quality-adjusted life-years saved.
Acknowledgments
This article was adapted from a dissertation submitted in
partial fulfillment of the requirements for a Master of Science degree
in Economic and Quantitative Methods in Health Care at City University,
London, UK.
References
Top
Abstract
Introduction
Subjects and Methods
Results
Discussion
References
1.
The Boston Area Anticoagulation Trial for Atrial
Fibrillation Investigators. The effect of low dose warfarin
on the risk of stroke in patients with nonrheumatic atrial
fibrillation. N Engl J Med. 1990;323:1505–1511.[Abstract]
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P. S.J. Miller, F. L. Andersson, and L. Kalra Are Cost Benefits of Anticoagulation for Stroke Prevention in Atrial Fibrillation Underestimated? Stroke, February 1, 2005; 36(2): 360 - 366. [Abstract] [Full Text] [PDF]
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 G. H Nilsson, I. Bjorholt, and I. Krakau Anticoagulant treatment of patients with chronic atrial fibrillation in primary health care in Sweden--a retrospective study of incidence and quality in a registered population Fam. Pract., December 1, 2004; 21(6): 612 - 616. [Abstract] [Full Text] [PDF]
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T. I. Shireman, P. A. Howard, T. F. Kresowik, and E. F. Ellerbeck Combined Anticoagulant-Antiplatelet Use and Major Bleeding Events in Elderly Atrial Fibrillation Patients Stroke, October 1, 2004; 35(10): 2362 - 2367. [Abstract] [Full Text] [PDF]
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 M. B. Dowd Anticoagulation in the Elderly Journal of Pharmacy Practice, April 1, 2004; 17(2): 94 - 102. [Abstract] [PDF]
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 J. A. Johnston, R. J. Cluxton Jr, P. C. Heaton, J. J. Guo, C. J. Moomaw, and M. H. Eckman Predictors of Warfarin Use Among Ohio Medicaid Patients With New-Onset Nonvalvular Atrial Fibrillation Arch Intern Med, July 28, 2003; 163(14): 1705 - 1710. [Abstract] [Full Text] [PDF]
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M. Man-Son-Hing and A. Laupacis Anticoagulant-Related Bleeding in Older Persons With Atrial Fibrillation: Physicians' Fears Often Unfounded Arch Intern Med, July 14, 2003; 163(13): 1580 - 1586. [Abstract] [Full Text] [PDF]
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M. Man-Son-Hing and A. Laupacis Balancing the Risks of Stroke and Upper Gastrointestinal Tract Bleeding in Older Patients With Atrial Fibrillation Arch Intern Med, March 11, 2002; 162(5): 541 - 550. [Abstract] [Full Text] [PDF]
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 J. Mason, P. Young, N. Freemantle, and R. Hobbs Safety and costs of initiating angiotensin converting enzyme inhibitors for heart failure in primary care: analysis of individual patient data from studies of left ventricular dysfunction BMJ, November 4, 2000; 321(7269): 1113 - 1116. [Abstract] [Full Text]
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T. J. Bungard, W. A. Ghali, K. K. Teo, F. A. McAlister, and R. T. Tsuyuki Why Do Patients With Atrial Fibrillation Not Receive Warfarin? Arch Intern Med, January 10, 2000; 160(1): 41 - 46. [Abstract] [Full Text] [PDF]
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 A. Lodwick State-of-the-Art Review: Warfarin Therapy: A Review of the Literature Since the Fifth American College of Chest Physicians' Consensus Conference on Antithrombotic Therapy Clinical and Applied Thrombosis/Hemostasis, October 1, 1999; 5(4): 208 - 215. [PDF]
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R. G. Holloway, C. G. Benesch, C. R. Rahilly, and C. E. Courtright A Systematic Review of Cost-Effectiveness Research of Stroke Evaluation and Treatment Stroke, July 1, 1999; 30(7): 1340 - 1349. [Abstract] [Full Text] [PDF]
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