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.

Coronary Artery Bypass Grafting (CABG) surgery and Coronary Artery Angioplasty (PTCA) in the treatment of chronic stable angina.

Diagnosis and treatment.

Cost-effectiveness analysis.

The study population consisted of patients with single-, double-, and triple-vessel disease (1VD, 2VD, 3VD) and left main artery disease (LMD) which resulted in chronic stable angina.

Secondary care and hospital. The economic study was conducted in the USA.

Effectiveness and cost data related to previous studies conducted between 1982 and 1995. The price year was not stated.

Effectiveness data were derived from a review of previous studies.

The outcomes assessed were mortality rate (for CABG versus medical management), reduction in angina symptoms, mortality rate and frequency of complications (medical therapy versus PTCA), and clinical and functional status, level of antianginal drugs, need for revascularization, rate of cardiac death, and rate of myocardial infarction (PTCA versus CABG).

The review placed an emphasis on data obtained from randomized controlled trials although at least one observational study was included.

Not stated.

Not stated.

Not stated.

The study involved the review of approximately 12 studies (at least 11 of these were randomized controlled trials).

Narrative review.

The studies differed in terms of size, length of follow-up, and sub-populations included.

The results showed that, for CABG versus medical management, the cumulative mortality rate was lower for CABG, demonstrating increased survival rate, particularly for those with more severe coronary artery disease. For medical therapy versus PTCA, the results showed a greater reduction in angina symptoms in patients undergoing PTCA (64% of patients were free of angina symptoms at 6 months compared with 45% for medical management)and a slightly improved exercise performance.4% of patients, however, had an acute myocardial infarction related to the procedure, 16% required a repeat PTCA by six months and 7% required CABG by six months. There was no difference in mortality. For CABG versus PTCA, clinical and functional status improved similarly for both groups, but the patients receiving PTCA required more antianginal drugs. Coronary artery restenosis for PTCA required surgical revascularization in 16% and repeat percutaneous revascularisation in 15% of cases. The rates of cardiac death and myocardial infarction were not different between the two treatments at 2.5 years. This latter finding was validated by studies in progress at the time of publishing. However, there is a 4-5 fold increase in the rate of revascularisation for PTCA in the first 12 months of follow-up.

The measures of benefit were mortality rate (for CABG versus medical management), reduction in angina symptoms, mortality rate and frequency of complications (for medical therapy versus PTCA) and clinical and functional status, level of antianginal drugs, rate of revascularizations, rate of cardiac death, and rate of myocardial infarction (for PTCA versus CABG).

The direct costs included the costs of medical management, including drugs, the cost of each intervention and pre- and post-testing procedures. Quantities and costs were not analysed separately. No discounting was stated. The quantity/cost boundary was not specified. The price year was not stated.

Although indirect costs (including economic and non-economic losses) were mentioned in the introduction to the study, it is not evident that these were included in the studies reviewed.

US dollars ($).

Not reported.

The results showed that for CABG versus medical management the cumulative mortality rate was lower for CABG, demonstrating increased survival rate, particularly for those with more severe coronary artery disease. For medical therapy versus PTCA, the results showed a greater reduction in angina symptoms in patients undergoing PTCA (64% of patients were free of angina symptoms at 6 months compared with 45% for medical management)and a slightly improved exercise performance.4%, however, had an acute myocardial infarction related to the procedure, 16% required a repeat PTCA by six months and 7% required CABG by six months. There was no difference in mortality.

For CABG versus PTCA, clinical and functional status improved similarly for both groups, but the patients receiving PTCA required more antianginal drugs. Coronary artery restenosis for PTCA required surgical revascularization in 16% and repeat percutaneous revascularisation in 15% of cases. The rates of cardiac death and myocardial infarction were not different between the two treatments at 2.5 years. However, there was a 4-5 fold increase in the rate of revascularisation for PTCA in the first 12 months of follow-up.

Not reported.

The costs and benefits were combined by means of the cost per QALY, defining a cost-effective strategy as that with a ratio between $20,000 and $40,000 (from a study published in 1992). The results were not explicitly given. CABG was then cost-effective for severe angina and left main coronary artery disease, and for mild angina with triple-vessel CAD. PTCA, however, was the cost-effective choice for patients with severe angina having single vessel CAD or double-vessel CAD.

Based on the data and findings reviewed the authors concluded that:

(a) medical therapy and PTCA should be individualized in low risk patients,

(b) CABG isrecommended for most high risk patients, particularly those with triple-vessel disease and impaired left ventricular function or ischemia at low workload. CABG is also cost-effective for patients with severe angina and left main coronary artery disease and for patients with mild angina and triple vessel disease,

(c) PTCA is cost-effective for patients with severe angina, and single- or multi-vessel disease and

(d) the cost-effectiveness of myocardial revascularization therapy is less likely to be as good in patients with mild coronary disease and lesser symptoms. CABG is cost effective for 1VD and highly cost-effective for 2 and 3VD and LMD in comparison with other interventions.

The authors reviewed apparently good quality studies, comparing a range of outcomes for various combinations of treatment. These studies, however, did not lend themselves to the synthesis of data in order to provide a common comparison measure between the strategies reviewed. More information is needed regarding the methodology employed in the review, in order to analyse the validity of the effectiveness results. The costs of each strategy were not separately reported. Rather, the general conclusions with respect to the cost-effectiveness of each strategy were presented, based on only two studies carrying out cost-utility analysis.

None stated.