Clinical effectiveness and cost-effectiveness of immediate angioplasty for acute myocardial infarction: systematic review and economic evaluation

Abstract

To review the clinical evidence comparing immediate angioplasty with thrombolysis, and to consider whether it would be cost-effective. Electronic databases. Experts in the field. For clinical effectiveness, a comprehensive review of randomised control trials (RCTs) was used for efficacy, and a selection of observational studies such as case series or audit data used for effectiveness in routine practice. RCTs of thrombolysis were used to assess the relative value of prehospital and hospital thrombolysis. Observational studies were used to assess the representativeness of patients in the RCTs, and to determine whether different groups have different capacity to benefit. Clinical effectiveness was synthesised through a narrative review with full tabulation of results of all included studies and a meta-analysis to provide a precise estimate of absolute clinical benefit. Consideration was given to the effect of the growing use of stents. The economic modelling adopted an NHS perspective to develop a decision-analytical model of cost-effectiveness focusing on opportunity costs over the short term (6 months). The results were consistent in showing an advantage of immediate angioplasty over hospital thrombolysis. The updated meta-analysis showed that mortality is reduced by about one-third, from 7.6% to 4.9% in the first 6 months, and by about the same in studies of up to 24 months. Reinfarction is reduced by over half, from 7.6% to 3.1%. Stroke is reduced by about two-thirds, from 2.3% with thrombolysis to 0.7% with percutaneous coronary intervention (PCI), with the difference being due to haemorrhagic stroke. The need for coronary artery bypass graft is reduced by about one-third, from 13.2% to 8.4%. Caution is needed in interpreting some of the older trials, as changes such as an increase in stenting and the use of the glycoprotein IIb/IIa inhibitors may improve the results of PCI. There is little evidence comparing prehospital thrombolysis with immediate PCI. Research on thrombolysis followed by PCI, known as 'facilitated PCI', is underway, but results are not yet available. Trials may be done in select centres and results may not be as good in lower volume centres, or out of normal working hours. In addition, much of the marginal mortality benefit of PCI over hospital thrombolysis may be lost if door-to-balloon time were more than an hour longer than door-to-needle time. Conversely, within the initial 6 hours, the later patients present, the greater the relative advantage of PCI. Results suggest that PCI is more cost-effective than thrombolysis, providing additional benefits in health status at some extra cost. In the longer term, the cost difference is expected to be reduced because of higher recurrence and reintervention rates among those who had thrombolysis. If both interventions were routinely available, the economic analysis favours PCI, given the assumptions of the model. However, very few units in England could offer a routine immediate PCI service at present, and there would be considerable resource implications of setting up such services. Without a detailed survey of existing provision, it is not possible to quantify the implications, but they include both capital and revenue: an increase in catheter laboratory provision and running costs. The greatest problem would be staffing, and that would take some years to resolve. A gradual incrementalist approach based on clinical networks, with transfer to centres able to offer PCI, may be used. In rural areas, one option may be to promote an increase in prehospital thrombolysis, with PCI for thrombolysis failures. There is a need for data on the long-term consequences of treatment, the quality of life of patients after treatment, and the effects of PCI following thrombolysis failure.