Health Technology Assessment 2000; Vol. 4: No. 23
View/Download full monograph in Adobe
Acrobat format (656 kbytes)
View/Download this 4-page summary in Adobe Acrobat format (suitable for printing)
Department of Public Health and Epidemiology, University of Birmingham, UK
* Corresponding author
Coronary artery stents are prosthetic linings inserted into coronary arteries via a catheter to widen the artery and increase blood flow to ischaemic heart muscle. They are used in the treatment of ischaemic heart disease (IHD).
IHD is a major cause of morbidity and mortality (123,000 deaths per annum) in the UK and a major cost to the NHS. Clinical effects of IHD include subacute manifestations (stable and unstable angina) and acute manifestations (particularly myocardial infarction [MI]). Treatment includes attention to risk factors, drug therapy, percutaneous invasive interventions (PCIs) (including percutaneous transluminal coronary angioplasty [PTCA] and stents) and coronary artery bypass graft surgery (CABG).
In the last decade there has been a steady and significant increase in the rate of PCIs for IHD. In the UK, rates per million population increased from 174 in 1991 to 437 in 1998. Stents are now used in about 70% of PCIs. Data from the rest of Europe suggest there is potential for PCI and stent rates to increase considerably. In the UK there is evidence of under-provision and inequity of access to revascularisation procedures.
The following questions were addressed.
A systematic review addressing the objectives was undertaken.
A search was made for RCTs comparing stents (inserted during a PTCA procedure) with PTCA alone or with CABG in any manifestation of IHD. The search strategy covered the period from 1990 to November 1999 and included searches of electronic databases (MEDLINE, EMBASE, BIDS ISI, The Cochrane Library), Internet sites, and handsearches of cardiology conference abstracts and 1999 issues of cardiology journals. Lead researchers and local clinical experts were contacted. Manufacturers submissions to the National Institute for Clinical Excellence were searched.
The search strategy was expanded to look for relevant economic analyses and information to inform the economic model (including searching MEDLINE, the NHS Economic Evaluation Database and the Database of Abstracts of Reviews of Effectiveness). Searches focused on research that reported costs and quality of life data associated with IHD and interventional cardiology.
For the review of clinical effectiveness, inclusion criteria were: (i) RCT design; (ii) study population comprising adults with IHD in native or graft vessels (including patients with subacute IHD or AMI); (iii) procedure involving elective insertion of coronary artery stents; (iv) elective PTCA (including PTCA with provisional stenting) or CABG as comparator; (v) outcomes defined as one or more of: combined event rate (or event-free survival), death, MI, angina, target vessel revascularisation, CABG, repeat PTCA, angiographic outcomes; (vi) trials that had closed and reported results for all or almost all recruited patients.
For the economic evaluation, studies of adults with IHD were included if they were of the following types: studies reporting UK costs; comparative economic evaluation combining both costs and outcomes; economic evaluations reporting costs and outcomes separately for the years 1998 and 1999 (to ensure current practice was included).
For the review of clinical effectiveness, data were extracted into data extraction forms and RCT quality was assessed using standard methods. Decisions relating to data extraction and quality were made by two independent reviewers. Disagreements were resolved by discussion and with the aid of a third party if there was any residual discrepancy. The quality assessment of cost-effectiveness analyses was based on a pre-determined check-list.
For the review of clinical effectiveness, abstracted data were collated in summary tables. Whenever possible, analysis was on an intention-to-treat basis. Meta-analyses were carried out when adequate data were available.
For the economic evaluation, cost data and health economic assessments were documented and evaluated.
Thirty-five RCTs which fulfilled the study criteria were found: 25 compared stent with PTCA for subacute IHD; three compared stents with CABG for subacute IHD; seven compared stents with PTCA following AMI. In general, the trials were open to bias, which introduced uncertainty. Despite this, convincing evidence of impact was identified in the following.
There was no clear evidence of impact on deaths, MI or CABG in comparison (1) or (2) above. Although trials were identified, there was insufficient evidence to draw any conclusions on the effectiveness of elective stent insertion versus CABG in subacute IHD.
The information identified contributes only to conclusions concerning elective stent insertion compared with PTCA in subacute IHD. There was wide variation in the estimates of cost, cost-effectiveness and costutility. Cost estimation, particularly for wider costs, was generally poor. It was probably conducted best in the context of the cost-effectiveness studies. These generally showed that cost/event-free survivor for elective stenting was equivalent to or less than that of PTCA. They support the view that higher initial costs of stents are outweighed by savings from reduced requirement for repeat PTCA. The majority of costutility studies reported cost/QALY estimations in the range of £20,000£30,000. Reasons why these estimates should be treated with caution were identified.
The efficiency of the use of stents compared with CABG in subacute IHD or stents compared with PTCA in AMI is unknown.
In subacute IHD (especially stable angina and unstable angina), there is evidence for the effectiveness of elective stents in reducing the need for repeat PTCA. This appears to represent an efficient use of resources. However, this assertion could be made with more confidence if the resource neutrality of stents could be confirmed using more rigorously derived cost data. There is currently insufficient evidence to assess the effectiveness of the extension of stent use to patients with baseline risks or indications different from those of the patients in the trials reviewed (for review question 1).
Meads C, Cummins C, Jolly K, Stevens A, Burls A, Hyde C. Coronary artery stents in the treatment of ischaemic heart disease: a rapid and systematic review. Health Technol Assess 2000;4(23).
The overall aim of the NHS R&D Health Technology Assessment (HTA) programme is to ensure that high-quality research information on the costs, effectiveness and broader impact of health technologies is produced in the most efficient way for those who use‹ manage and work in the NHS. Research is undertaken in those areas where the evidence will lead to the greatest benefits to patients, either through improved patient outcomes or the most efficient use of NHS resources.
The Standing Group on Health Technology advises on national priorities for health technology assessment. Six advisory panels assist the Standing Group in identifying and prioritising projects. These priorities are then considered by the HTA Commissioning Board supported by the National Coordinating Centre for HTA (NCCHTA).
The research reported in this monograph was commissioned by the HTA programme (project number 99/15/01) on behalf of the National Institute for Clinical Excellence (NICE). Rapid reviews are completed in a limited time to inform the appraisal and guideline development processes managed by NICE. The review brings together evidence on key aspects of the use of the technology concerned. However, appraisals and guidelines produced by NICE are informed by a wide range of sources. Any views expressed in this rapid review are therefore those of the authors and not necessarily those of the HTA programme, NICE or the Department of Health.
Reviews in Health Technology Assessment are termed systematic when the account of the search, appraisal and synthesis methods (to minimise biases and random errors) would, in theory, permit the replication of the review by others.
Criteria for inclusion in the HTA monograph series
Reports are published in the HTA monograph series if (1) they have resulted from work either prioritised by the Standing Group on Health Technology, or otherwise commissioned for the HTA programme, and (2) they are of a sufficiently high scientific quality as assessed by the referees and editors.
Series Editors: Andrew Stevens, Ken Stein and John Gabbay
Monograph Editorial Manager: Melanie Corris
The editors and publisher have tried to ensure the accuracy of this report but do not accept liability for damages or losses arising from material published in this review.
©2000 Crown Copyright