|Cost-effectiveness of coronary artery bypass grafts versus percutaneous coronary intervention for revascularization of high-risk patients
|Stroupe KT, Morrison DA, Hlatky MA, Barnett PG, Cao L, Lyttle C, Hynes DM, Henderson WG
This is a critical abstract of an economic evaluation that meets the criteria for inclusion on NHS EED. Each abstract contains a brief summary of the methods, the results and conclusions followed by a detailed critical assessment on the reliability of the study and the conclusions drawn.
This study examined the cost-effectiveness of percutaneous coronary intervention (PCI) versus coronary artery bypass graft (CABG) in high-risk patients with medically refractory myocardial ischaemia. The authors concluded that PCI patients had significantly lower costs than CABG patients and at least as good survival, which made PCI the preferred surgery for these patients. The study was well conducted and satisfactorily presented. The authors’ conclusions appear to be valid.
Type of economic evaluation
This study examined the cost-effectiveness of percutaneous coronary intervention (PCI) versus coronary artery bypass graft (CABG) in high-risk patients with medically refractory myocardial ischaemia. High-risk patients were defined as those with one or more of the following: prior open heart surgery, over 70 years old, left ventricular ejection fraction under 0.35, myocardial infarction within seven days, or requiring an intra-aortic balloon pump.
Two urgent revascularisation procedures, namely PCI and CABG, were compared.
This economic evaluation was based on data from a single study and two time horizons were considered: three and five years. The authors stated that a third-party payer perspective was adopted.
The clinical data were derived from a randomised controlled trial (RCT), carried out by the Department of Veteran Affairs (VA) in 16 medical centres. A sample of 445 patients was included in this cost-effectiveness analysis: 218 (mean age 68 ± 9 years; 99% men) in the PCI group and 227 (mean age 67 ± 9 years; 99% men) in the CABG group. Patients were followed-up until their death or the end of the study. They were enrolled between February 1995 and February 2000 and followed-up until September 2004. The key clinical endpoint was survival.
Monetary benefit and utility valuations:
Measure of benefit:
Survival was the summary benefit measure. Life-years (LYs) were discounted at an annual rate of 3%.
The economic analysis included the costs of initial and subsequent revascularisation procedures and hospital stay, out-patient care, rehabilitation, mental health care, and long-term care. The data on resource use were derived from the sample of patients enrolled in the clinical trial using information from VA and Medicare databases based on diagnosis-related group prices. Costs were in US dollars ($) and were discounted at 3% per annum. The price year was 2004.
Analysis of uncertainty:
Bias-corrected accelerated bootstrapping was used to estimate the confidence intervals (CIs) around the mean costs after adjusting for skew in the economic data. A similar approach was used to assess the precision of the cost-effectiveness estimates. A deterministic sensitivity analysis used VA short-term hospital standard costs from areas different from those considered in the primary analysis. In an alternative scenario, pharmacy costs from 1999 to 2004 were included.
After three years, the total costs were $63,896 with PCI and $84,364 with CABG (difference $20,468, 95% CI 13,918 to 27,569). After five years, total costs were $81,790 with PCI and $100,522 with CABG (difference $18,732, 95% CI 9,873 to 27,831).
The probability of survival was 0.82 with PCI and 0.79 with CABG (p=0.34) after three years and 0.75 with PCI and 0.70 with CABG (p=0.21) after five years. LYs gained were 3.97 with PCI and 3.78 with CABG (p=0.18).
PCI was a dominant strategy as it was less expensive and more effective (not significant) than CABG, despite the need for more repeat revascularisation procedures over the study period. This was the case in 92.6% of simulations at three years and in 89.4% of simulations at five years. The deterministic sensitivity analysis showed that the base-case findings were robust.
The authors concluded that PCI patients had significantly lower costs than CABG patients and at least as good survival, which made PCI the preferred surgical approach for high-risk patients with medically refractory myocardial ischaemia.
The selection of the comparators was appropriate as the two interventions were valid surgical procedures for this patient population.
The clinical evidence was derived from a published trial and the key details of its methodology and its results were reported. In general, a multicentre RCT is considered to be a valid source of data, given the strengths of its design. The trial was based on the intention-to-treat principle and the patient groups were not significantly different at baseline. These additional points enhance the validity of the clinical estimates. The benefit measure was appropriate as survival is the key outcome of these surgical procedures. Survival, and LYs can also be compared with the benefits of other health care interventions.
The categories of costs reflected the perspective, and it appears that all the costs borne by the third-party payer over the study period were included. The sources of data were extensively reported for each category of costs. As payers’ databases were used, macro-categories were reported and the costs were not broken down into individual items. In general, the economic analysis was well reported. The price year, the use of discounting, the use of statistical analyses, and the additional assumptions made in the sensitivity analysis were clearly presented, which improves the transparency and quality of the overall cost analysis.
Analysis and results:
Total and incremental results were reported for both time horizons. The authors did not calculate cost-effectiveness ratios, which was appropriate given the dominance of PCI over CABG. The issue of uncertainty was satisfactorily addressed in the sensitivity analysis and the key findings were clearly reported and displayed using tables and diagrams. The authors noted that, at the time of the trial, drug-eluting stents were not being used in PCI, but their inclusion was likely to lead to only a slight increase (about 5%) in the cost of PCI. They also emphasised that their results differed from most other clinical studies comparing CABG and PCI, where CABG was found to be more effective. The reason for this difference was probably the very high-risk patient population analysed in this trial.
The study was well conducted and satisfactorily presented. The authors’ conclusions appear to be valid.
Supported by the National Institutes of Health, and the Cooperative Studies Program of the United States Department of Veteran Affairs.
Stroupe KT, Morrison DA, Hlatky MA, Barnett PG, Cao L, Lyttle C, Hynes DM, Henderson WG. Cost-effectiveness of coronary artery bypass grafts versus percutaneous coronary intervention for revascularization of high-risk patients. Circulation 2006; 114(12): 1251-1257
Other publications of related interest
Morrison DA, Sethi G, Sacks J, Henderson W, Grover F, Sedlis S, Esposito R, Ramanathan K, Weiman D, Saucedo J, Antakli T, Paramesh V, Pett S, Vernon S, Birjiniuk V, Welt F, Krucoff M, Wolfe W, Lucke JC, Mediratta S, Booth D, Barbiere C, Lewis D. Angina With Extremely Serious Operative Mortality Evaluation (AWESOME) Investigators. Percutaneous coronary intervention versus coronary artery bypass graft surgery for patients with medically refractory myocardial ischemia and risk factors for adverse outcomes with bypass: a multicenter, randomized trial. Journal of the American College of Cardiology 2001; 38: 143-149.
Hlatky MA, Rogers WJ, Johnstone I, Boothroyd D, Brooks MM, Pitt B, Reeder G, Ryan T, Smith H, Whitlow P, Wiens R, Mark DB, Bari Investigators. Medical care costs and quality of life after randomization to coronary angioplasty or coronary bypass surgery. New England Journal of Medicine 1997; 336: 92-99.
Hoffman SN, TenBrook JA, Wolf MP, Pauker SG, Salem DN, Wong JB. A meta-analysis of randomized controlled trials comparing coronary bypass graft with percutaneous transluminal coronary angioplasty: one- to eight-year outcomes. Journal of the American College of Cardiology 2003; 41: 1293-1304.
Subject indexing assigned by NLM
Aged; Angioplasty, Balloon, Coronary /adverse effects /economics; Coronary Artery Bypass /adverse effects /economics; Coronary Artery Disease /economics /physiopathology /therapy; Cost-Benefit Analysis; Female; Health Care Costs; Humans; Male; Middle Aged; Myocardial Ischemia /economics /physiopathology /therapy; Myocardial Revascularization /adverse effects /economics /methods /statistics & Quality of Health Care; Risk Factors; Survival Analysis; Treatment Outcome; numerical data
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Date abstract record published