| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
(Stroke. 2004;35:1490.)
© 2004 American Heart Association, Inc.
Comments, Opinions, and Reviews |
From the Division of Clinical Neurosciences (P.S., M.D., S.L., J.W.), University of Edinburgh, Western General Hospital, Edinburgh, UK; the Department of Internal Medicine (E.B.), Ulleval Hospital, Oslo, Norway; the Section of Public Health Sciences, Division of Community Health Sciences (J.F.), University of Edinburgh, Edinburgh, UK; the Department of Neurology (P.H.). Royal Melbourne Hospital, Melbourne, Australia; the University Department of Geriatric Medicine (J.K.). Southampton General Hospital, Southampton, UK; and HealthEcon (A.N.), Basel, Switzerland.
Correspondence to Prof Peter Sandercock, Department of Clinical Neurosciences, Western General Hospital, Edinburgh EH4 2XU. E-mail pags{at}skull.dcn.ed.ac.uk
| Abstract |
|---|
|
|
|---|
Methods The authors formed a discussion panel to develop the decision-analysis model of acute stroke care. It consisted of Markov state-transition processes, with probabilities of different health states determined by certain key variables. The range of estimates of efficacy of recombinant tissue plasminogen activator (rt-PA) was taken from an update to a Cochrane systematic review of randomized trials of thrombolysis. Data on outcome after stroke were taken from our hospital-based stroke register, supplemented by data derived from relevant literature sources.
Results The model suggested that compared with standard care, if eligible patients were treated with rt-PA up to 6 hours, there was a 78% probability of a gain in quality-adjusted survival during the first year, at a cost of £13 581 per quality-adjusted life-year (QALY) gained. Over a lifetime, rt-PA was associated with cost-savings of £96 565 per QALY. However, the estimates were imprecise and highly susceptible to the assumptions used in the economic model; under several plausible assumptions, rt-PA was much less cost-effective than standard care, and under others, a great deal more cost-effective.
Conclusions The estimates of effectiveness and cost-effectiveness were imprecise. Although the benefits appeared promising, the data did not support the widespread use of thrombolytic therapy outside the terms of the current restricted license in routine clinical practice in the NHS. There is a case for new large-scale randomized trials comparing thrombolytic therapy with control up to 6 hours to determine more precisely the effects of rt-PA on short-term and long-term survival and its cost-effectiveness when used in a wider range of patients.
Key Words: thrombolytic therapy tissue plasminogen activator cerebral infarction cost-benefit analysis
| Introduction |
|---|
|
|
|---|
See Editorial Comment, page 1497
| Subjects and Methods |
|---|
|
|
|---|
Study Question
From the perspective of the UK NHS, is thrombolytic treatment for acute ischemic stroke (compared with standard care) cost-effective as judged by the incremental cost per quality-adjusted life-year (QALY) gained?
Perspective
The perspective was a broad health care and personal social services perspective. We included the direct costs of hospital stay, rehabilitation, and long-term care. We did not include assessments of any indirect economic costs, such as loss of work-related earnings, or of the capital and revenue costs of developing services for patients with acute stroke to the point at which acute stroke care was delivered across the whole NHS to the standard required.
Assessment of Alternatives to Thrombolytic Treatment
It is difficult to define, in economic terms, a standard package of general care for patients with acute stroke (even more so to define one for patients treated with thrombolysis). We have therefore assumed that the alternative treatments being compared are "standard care" and "standard care plus thrombolysis."
Form of Evaluation
We have adopted a cost-utility approach, assessing health gains in QALYs. We have modeled costs and effectiveness over the short-term (1 year) and the long-term (lifetime).
Steps to Improve Generalizability of Results
The patients included in the trials of thrombolysis were highly selected and were largely recruited from non-UK centers. So, to produce results that were more relevant to the NHS, we undertook a modeling approach, applying data on efficacy from the trials to a population of stroke patients treated within the NHS (or similar publicly funded health service).
Choice of Measure of Benefit
The use of QALYs as the measure of benefit enabled us to encompass the utility values that stroke patients assign to the different health states after stroke (ie, death, survival in a dependent state, or survival in an independent state).5,6
Decision-Analysis Model
The authors formed a discussion panel to construct a decision-analysis model of the pathways that acute stroke patients follow after being admitted to hospital.4 The model was constructed by discussion among the reviewers, analysis of our own stroke registry (Lothian Stroke Register) data, and review of the literature. The model was entered into a software package (Data 3.5 software; TreeAge Software Inc) and is shown in Figure 1. We defined 5 groups of patients (see Figure 1 legend for definitions). Table 1 lists all of the base-case values (with plausible ranges) used in the model and the sources of the estimates. These include estimates of treatment effect for rt-PA to those that formed the basis for its current approval for use in clinical practice within 3 hours. To predict the health and economic outcomes of rt-PA after the first year, we used a Markov modeling approach.79 The Markov model used age-specific mortality, risk of recurrent stroke, and stroke-specific case-fatality to estimate the probabilities of being dead, dependent, and independent at the beginning of each year. The Markov process was run repeatedly in 1-year cycles until the end of the cohort lifetime, and totals were computed for the accumulated health outcomes and costs.
|
|
Assumptions About Cost of Implementing rt-PA
We sought to assess the typical additional costs of implementing rt-PA treatment in a "typical" district general hospital. However, we were unable to define a nationally agreed level of resource use required to deliver thrombolysis for acute stroke or to obtain reliable measures of the variation in the current level (and cost) of acute stroke care in UK hospitals. We therefore sought to identify, in a qualitative way, the specific extra resources we considered necessary to deliver thrombolysis (in the context of a randomized controlled trial) in our own hospital (Table 2). However, the resources currently allocated to acute stroke care vary greatly between centers across the UK, so any quantitative estimates of the extra implementation costs derived from these local data could not be reliably extrapolated to other hospitals in the UK.
|
Adjustment for Timing of Costs and Benefits
We accounted for the longer time horizon over which costs and health benefits may accrue by discounting outcomes and cost at an annual rate of 6%.
Scenarios Modeled
We performed a number of 1-way sensitivity analyses and threshold analyses to explore the impact of varying key parameters in the model: rt-PA efficacy (we used a range that encompassed larger benefits expected when used in a highly selected population within 3 hours and expected smaller benefits when used in a wider variety up to 6 hours); system efficiency (this ranged from the small proportion currently treated to a scenario with greatly increased efficiency leading to a high proportion treated); utility values; costs of rt-PA treatment; length of hospital stay; and unit cost per inpatient day. We also performed a multiway first-order Monte Carlo simulation to determine how likely certain levels of cost-effectiveness were when we simultaneously incorporated all ranges of values for variables listed in Table 1.
| Results |
|---|
|
|
|---|
|
Cost-Effectiveness at End of the Cohort Lifetime
Costs accrue in the short-term (eg, initial acute care), whereas survival gains accumulate over a far longer period, and analyses performed at 12 months therefore underestimate expected yield (eg, in terms of QALYs gained) relative to costs. Nursing home/long-term care is higher for a stroke survivor with high levels of disability, and hence the cost-savings associated with reduced disability, are large and only partly offset by the costs associated with increased survival. The base-case analysis showed that over the cohort lifetime, giving rt-PA then became the dominant strategy (Table 4). Treatment with rt-PA was more effective (gain in QALYs of 3.63 per 100 patients treated), less expensive than standard treatment (cost savings of £350 532), and resulted in a reduced cost of £96 565 per QALY gained. The multiway Monte Carlo simulation showed that there was a 76.6% probability of increased QALYs. If we assume that rt-PA increases QALYs, the 5th and 95th percentiles for the incremental cost-effectiveness ratios for this group were £908 153 (net savings) and £37 858 (net savings) per QALY gained.
|
Sensitivity Analyses
The lower halves of Tables 3 and 4
summarize the sensitivity analyses. The impact of assuming the most optimistic estimate of rt-PA efficacy was to increase the number of QALYs gained from 3.63 to 19.41, reduce the costs from £350 532 to £267 713 per 100 patients treated, and change the marginal cost-effectiveness ratio from £96 565 to £13 793 saved per QALY gained. When we assumed the least favorable estimate of rt-PA effectiveness, rt-PA resulted in a loss of 13.21 QALYs, and the incremental cost-effectiveness ratio could not be calculated. Detailed sensitivity analyses are presented in the full report.4
| Discussion |
|---|
|
|
|---|
Summary of Previous Work
Our results are not as optimistic as earlier estimates. From the perspective of the North American health care system (which included nursing home costs), for every 1000 patients treated, rt-PA increased hospitalization costs by $1.7 million but decreased rehabilitation costs by $1.4 million and nursing home costs by $4.8 million.1 Multiway sensitivity analyses indicated a >90% probability of cost-savings. The study had some limitations for current health care planning outside the USA: the estimate of efficacy was based on a single trial;14 costs were based on the US health care system; the possibility that treatment might increase case fatality was not modeled; and the estimate of the gain in QALYs was very imprecise (and included the possibility of almost no benefit). A further study, commissioned by a pharmaceutical company (but conducted by an independent economist), concluded that the savings related to disability and long-term care considerably outweighed any potential extra costs of acute therapy, given a broad cost perspective and a time horizon of
2 years.3 However, the authors also pointed out that the fixed costs of developing and maintaining a capability to diagnose acute stroke and provide early thrombolysis would need to be taken into account in a more comprehensive analysis. Furthermore, any downstream savings attributed to the avoidance of social care costs associated with disability are unlikely to be very convincing to budget holders focused on hospital and drug cost alone.3
Why Might Our Results Be Different?
As expected, the cost-effectiveness estimate at 12 months was heavily influenced by the source of the data in the model.12 This may invalidate the comparison between our study and previous studies of cost-effectiveness of rt-PA in stroke13 and may explain the different short-term results. In contrast to earlier studies, we found that the cost-savings were not realized within the first 1 to 2 years after treatment. One likely explanation is that the other studies were based on more optimistic estimates of rt-PA effectiveness, from the NINDS trial alone, in which treatment was given within 3 hours14 or just 3 of the major rt-PA trials;1416 however, our sensitivity analyses did include a value for the effectiveness of rt-PA comparable to that seen in NINDS. Earlier studies also used more favorable values for patients preferences.17,18 We based our estimates of the effectiveness of rt-PA on the results of a systematic review of all the available evidence from randomized controlled trials of rt-PA to date. Furthermore, we used a more conservative estimate of the patient valuation of the dependent state, which, as it turned out, was close to the estimate derived from a recent systematic review of patient utilities after stroke.6
Generalizability of These Results
Another uncertainty relates to the generalizability of the findings.12 It is likely that both resource use (eg, length of stay) and the valuation of resources (eg, mean unit cost per inpatient day) will vary considerably within the NHS. Hence, we used national official figures to "average out" local differences in unit costs,19 and we believe that the resources used by patients registered in the Lothian Stroke Register are reasonably representative of the resources used by stroke patients admitted to other UK hospitals. Our analysis did not include the costs of implementing rt-PA in NHS hospitals. We assumed that there were no capacity constraints in the health care system and that there were no extra costs associated with giving rt-PA to more patients. For example, we assumed that all admissions were "equal," regardless of when they occur; that CT scanning equipment was always readily available, and that the correct number and mix of health care professionals and hospital beds were always in place. We sought to assess the additional costs of developing stroke services to deliver rt-PA treatment by identifying the specific service components we considered likely to be required to deliver thrombolysis in our hospital, over and above those required for "standard" acute stroke care (Table 2). However, we were unable to find a nationally agreed level of resource use required to deliver thrombolysis for acute stroke and no reliable measures of the variation in the current level (and cost) of acute stroke care in the NHS.
| Conclusions |
|---|
|
|
|---|
However, the range of possible incremental cost-effectiveness ratios was considerable, and the conclusions from the economic modeling were very sensitive to the economic assumptions made and a number of parameters, including the effectiveness of rt-PA (detailed in Table 1). The less favorable estimates indicated that rt-PA could be either marginally cost-effective or harmful (ie, standard therapy was the preferred option).
The primary analyses suggested cost-effectiveness or even cost-savings. However, in view of the lack of precision of the estimates and lack of data on the cost of "rolling out" the treatment to the many centers that do not currently have the resources to give rt-PA, we were unable to model the cost of widespread use of rt-PA for stroke in the UK. However, these data do not preclude the use of rt-PA for the treatment of patients who meet the stringent conditions of the present product license (in the small number of appropriately staffed and equipped centers).
Implications for Research
The cost-effectiveness of rt-PA could not be assessed reliably because of the imprecise estimates of its efficacy. Large-scale randomized trials would be needed to provide sufficiently precise estimates.
If trials established reliably that thrombolysis was effective, then better estimates of the costs of implementing thrombolysis for acute stroke in the NHS will be needed. A more "dynamic system approach" to explore the relationships between different system components and their impact on patient treatment strategies would be informative.
Because the cost-effectiveness estimates were very sensitive to a relatively small set of parameters, future research could focus on the relationship between thrombolytic therapy, resource consequences, and health effects. More data are needed on the effect of the level of disability at 6 months after stroke on subsequent survival, recurrence, and eligibility for re-treatment with thrombolysis.
| Appendix I |
|---|
|
|
|---|
| Acknowledgments |
|---|
| Footnotes |
|---|
Received May 15, 2003; revision received January 7, 2004; accepted February 16, 2004.
| References |
|---|
|
|
|---|
2. Dewey H. Cost of acute stroke: is rt-PA cost-effective? Paper presented at: 6th International Symposium on Stroke and Thrombolytic Therapy; 2000; Hamilton Island, Australia.
3. Chambers MG, Koch P, Hutton J. Development of a decision-analytic model of stroke care in the United States and Europe. Value Health. 2002; 5: 8297.[CrossRef][Medline] [Order article via Infotrieve]
4. Sandercock P, Berge E, Dennis M, Forbes J, Hand P, Kwan J, Lewis S, Lindley R, Neilson A, Thomas B, Wardlaw J. A systematic review of the effectiveness, cost-effectiveness and barriers to implementation of thrombolytic and neuroprotective therapy for acute ischaemic stroke in the NHS. Health Technology Assessment. 2002; 6: 1112.
5. Dorman P, Dennis MS, Sandercock P. Are the modified "simple questions" a valid and reliable measure of health related quality of life after stroke? J Neurol Neurosurg Psychiatry. 2000; 69: 487493.
6. Post PN, Stiggelbout A, Wakker P. Utility of health states after stroke. A systematic review of the literature. Stroke. 2001; 32: 14251429.
7. Sonnenberg FA, Beck JR. Markov models in medical decision making; a practical guide. Med Decis Making. 1993; 13: 322328.
8. Bellsey J, Sheldon AM. Healthcare applications of decision analytic modelling. Health Econ Prev Care. 2000; 1: 3743.
9. Milne R, Nuitjen M, Weinstein M, Zhou X. Decision analytic modelling in the evaluation of health technologies: a consensus statement. Pharmacoeconomics. 2000; 12: 443444.
10. Vermeer F, Simoons ML, de Zwan C. Cost benefit analysis of early thrombolytic treatment with intracoronary streptokinase. Br Heart J. 1988; 59: 527534.
11. Simoons ML, Vos J, Martens LL. Cost-utility analysis of thrombolytic therapy. Eur Heart J. 1991; 12: 694699.[Medline] [Order article via Infotrieve]
12. Briggs AH, Gray AM. Handling uncertainty when performing economic evaluations of healthcare interventions. Health Technol Assess. 1999; 3: 1134.[Medline] [Order article via Infotrieve]
13. Donaldson C, Currie C, Mitton, C. Cost-effectiveness analysis in health care: contraindications. BMJ. 2002; 235: 891894.
14. The National Institute of Stroke and Neurological Disorders rt-PA Stroke Study Group. Tissue plasminogen activator for acute ischemic stroke. N Engl J Med. 1995; 333: 15811587.
15. Hacke W, Kaste M, Fieschi C, Toni D, Lesaffre E, von Kummer R et al. Intravenous thrombolysis with recombinant tissue plasminogen activator for acute hemispheric stroke. JAMA. 1995; 274: 10171025.
16. Hacke W, Kaste M, Fieschi C, von Kummer R, Davalos A, Meier D, Larrue V, Bluhmki E, Davis S, Donnan G, Schneider D, Diez-Tejedor E, Trouillas P. Randomised double-blind placebo-controlled trial of thrombolytic therapy with intravenous alteplase in acute ischaemic stroke (ECASS II). Lancet. 1998; 352: 12451251.[CrossRef][Medline] [Order article via Infotrieve]
17. Gage BF, Cardinalli AB, Owens DK. The effect of stroke and stroke prophylaxis with aspirin or warfarin on quality of life. Arch Intern Med. 1996; 156: 18291836.
18. Solomon NA, Glick HA, Russo CJ, Lee J, Schulman KA. Patient preferences for stroke outcomes. Stroke. 1994; 25: 17211725.[Abstract]
19. National Health Service in Scotland, Information and Statistics Division, Common Services Agency, Edinburgh. Scottish Health Service Costs. Year ended 31st March 1999. Edinburgh; 1999.
20. Wardlaw JM, Lewis SC, Dennis MS, Counsell C, McDowall M. Is visible infarction on computed tomography associated with an adverse prognosis in acute ischaemic stroke? Stroke. 1998; 29: 1319.
21. Hankey GJ, Jamrozik K, Broadhurst RJ, Forbes S, Burvill PW, Anderson CS, Stewart-Wynne EG. Five-year survival after first-ever stroke and related prognostic factors in the Perth community stroke study. Stroke. 2000; 31: 20802086.
22. Wardlaw JM, del Zoppo G, Yamaguchi T, Berge E. Thrombolysis for acute ischaemic stroke (Cochrane Review). In: The Cochrane Library, Issue 3, 2003. Oxford: Update Software.
23. Scottish Health Service Costs 199899 for Western General Hospital. Edinburgh; 1999.
24. Forbes JF, Dennis MS. Costs and health outcomes of stroke patients. Final Project Report submitted to the Health Service and Public Health Research Committee. Edinburgh: Chief Scientist Office, Scottish Home and Health Department; 1995.
25. British National Formulary (BNF40), September 2000.
26. Chambers M. The MEDTAP model. Cerebrovasc Dis. 1998; 8 (suppl 4): 50. Abstract.
27. Chambers M, Hutton J, Gladman J. Cost-effectiveness analysis of antiplatelet therapy in the prevention of recurrent stroke in the UK. Pharmacoeconomics. 1999; 16: 577593.[CrossRef][Medline] [Order article via Infotrieve]
28. Boland A, Bagust A, Haycox A, Hill R, Mujica Mota R, Walley T, Dickson R. Early thrombolysis for the treatment of acute myocardial infarction: a systematic review and economic evaluation. Health Technol Assess. 2003; 7: 1136.[Medline] [Order article via Infotrieve]
29. Benade M, Warlow C. Costs and benefits of carotid endarterectomy and associated preoperative arterial imaging: a systematic review of health economic literature. Stroke. 2003; 33: 629638.
Related Article:
Stroke 2004 35: 1497-1498.
This article has been cited by other articles:
![]() |
O. Saka, A. McGuire, and C. Wolfe Cost of stroke in the United Kingdom Age Ageing, January 1, 2009; 38(1): 27 - 32. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. Kobayashi, M. Skowronska, T. Litwin, and A. Czlonkowska Lack of experience of intravenous thrombolysis for acute ischaemic stroke does not influence the proportion of patients treated Emerg. Med. J., February 1, 2007; 24(2): 96 - 99. [Abstract] [Full Text] [PDF] |
||||
![]() |
L. Ehlers, G. Andersen, L. B. Clausen, M. Bech, and M. Kjolby Cost-Effectiveness of Intravenous Thrombolysis With Alteplase Within a 3-Hour Window After Acute Ischemic Stroke Stroke, January 1, 2007; 38(1): 85 - 89. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. R. Earnshaw, A. V. Joshi, M. R. Wilson, and J. Rosand Cost-Effectiveness of Recombinant Activated Factor VII in the Treatment of Intracerebral Hemorrhage Stroke, November 1, 2006; 37(11): 2751 - 2758. [Abstract] [Full Text] [PDF] |
||||
![]() |
K. Z. Bambauer, S. C. Johnston, D. E. Bambauer, and J. A. Zivin Reasons why few patients with acute stroke receive tissue plasminogen activator. Arch Neurol, May 1, 2006; 63(5): 661 - 664. [Abstract] [Full Text] [PDF] |
||||
![]() |
B. M. Demaerschalk and T. R. Yip Economic Benefit of Increasing Utilization of Intravenous Tissue Plasminogen Activator for Acute Ischemic Stroke in the United States Stroke, November 1, 2005; 36(11): 2500 - 2503. [Abstract] [Full Text] [PDF] |
||||
![]() |
D. B. Matchar Editorial Comment--What Can Models Teach Us About Stroke Treatment?: Sorting Out the Missing Bits Stroke, June 1, 2004; 35(6): 1497 - 1498. [Full Text] [PDF] |
||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
Stroke Home | Subscriptions | Archives | Feedback | Authors | Help | AHA Journals Home | Search Copyright © 2004 American Heart Association, Inc. All rights reserved. Unauthorized use prohibited. |