CABG offered significantly lower mortality and less angina at one year10
but the increase in quality adjusted life years compared with PCI was negligible and came at a considerable increase in cost, at least in the first year. Greater follow up costs associated with PCI were not enough to make up for the higher initial hospitalisation costs with CABG. Exploratory subgroup analyses suggest that these differences are consistent for all the obvious subgroups.
The mortality results, with CABG being significantly better than PCI, probably reflect the play of chance. In the ARTS trial, the one year mortality rate for both PCI and CABG was the same as the PCI mortality in the present trial.8
In contrast, ERACI II showed a significant survival benefit for stenting.9
This considerable uncertainty about what the real difference is in mortality and in utility between CABG and PCI makes problematic a formal estimate of a one year time horizon, as well as long term incremental cost effectiveness analysis. The in-trial mortality advantage for CABG would result in a favourable incremental cost effectiveness ratio in cost per life year saved extended long term. However, whether this result may be considered meaningful depends entirely on the generalisability of the mortality data in this trial, which favoured CABG.
Other randomised trials comparing PCI with CABG have been carried out during the past 15 years. In the RITA-1 (randomised intervention treatment of angina) trial, 1011 patients with coronary artery disease (45% single vessel, 55% multivessel) were randomly assigned between May 1988 and November 1991 to an initial strategy of PTCA or CABG.1,14
No difference was noted in the incidence of death or the composite of death plus myocardial infarction. There were more repeat interventions and a greater degree of angina in the PTCA group. Total health care costs over five years, derived by similar methods to those used for SoS, were not significantly different between groups (mean difference £426, 95% CI −£383 to £1235, p
BARI (bypass angioplasty revascularisation investigation) and EAST (Emory angioplasty versus surgery trial) compared state of the art PTCA with CABG from the late 1980s.2,3
In each of these studies there was similar survival in both arms but more revascularisations with PTCA. While both studies reported higher costs initially with CABG, this cost difference narrowed over five years in BARI and over eight years in EAST.12,16
Both PTCA (or PCI) and CABG have changed dramatically since the time of those trials, especially with the introduction of coronary stents30,31
and minimally invasive or off pump CABG.32
Costs, on an inflation adjusted basis, have fallen, at least in one study from the USA, for both forms of coronary revascularisation.33,34
The older trials that compared balloon PTCA with CABG are less relevant to the current situation, in which the standard practice of PCI has come to include the use of intracoronary stents and glycoprotein IIb/IIIa inhibitors. The other major multinational trial with an economic analysis besides SoS that has been conducted since the late 1990s, comparing PCI with CABG, is ARTS.8
In ARTS, costs were similar to those in SoS. The in-hospital costs averaged $10 652 (£7531) with CABG and $6441 (£4553) with PCI, a difference of $4212 (£2977) (p < 0.001). This difference narrowed due to repeat revascularisation in the PCI arm to a one year cost of $13 638 (£9638) with CABG and $10 665 (£7537) with PCI, a difference of $2973 (£2101) (p < 0.001).
A potential change in the practice of PCI in the near future may have economic as well as clinical consequences. In early trials, drug eluting stents have been shown to reduce dramatically the restenosis rate after PCI.35,36
If these early results are borne out and restenosis is largely eliminated, then the economic advantage of CABG over PCI during follow up may be attenuated. However, any economic advantage in follow up may not overcome increased initial costs if these new stents are expensive. While this technical advance may shift decision making further towards PCI, its economic consequences remain uncertain.
As important as changes in revascularisation are, medical treatment has also changed, with efforts to control risk factors aggressively, including lipids, blood pressure, diabetes, exercise, diet, and smoking cessation. This will be addressed in detail in the COURAGE (clinical outcomes utilising revascularisation and aggressive drug evaluation) trial that began enrolment in June 1999 and will compare coronary intervention with aggressive medical management versus aggressive medical management alone.37
Changes in medical treatment will also have profound economic consequences with cost of more intense treatment offset by savings from reduced events.
Given the availability of only one year outcomes for all patients in SoS, the conclusions are inherently limited. In addition, CABG is, in the absence of complications, associated with a more difficulty period of recovery. While this was not captured in the utility data, as the first postprocedural measurement was at six months, such a difference is short lived and unlikely to translate into a substantial difference in quality adjusted life years. Both forms of revascularisation appear to be good forms of treatment for angina. While CABG offers better relief of chest pain initially, with time and additional procedures as needed, patients treated with PCI can achieve similar results. For patients equally suitable to either procedure, CABG is initially much more expensive, but this difference may be reduced or disappear over time if additional procedures are performed in the PCI arm. CABG may look more favourable in the longer term, as there will be little reason to expect greater long term induced costs with CABG than with PCI, and over several years patients who have undergone CABG may continue to have less angina.16,38
Thus, the in-trial ratio of cost per life year gained provides a very restricted picture of the relative cost effectiveness of the two procedures: a more meaningful picture requires reliable estimates of long term relative cost and benefit.
The economics of CABG and PCI have changed over the past 10–15 years with technical advances and secular trends. Continuing change in both procedures will lead to an ongoing need for high quality randomised studies measuring clinical and economic outcomes of the two forms of revascularisation, as well as inevitably more speculative modelling of possible longer term costs and effects.