Economic analysis including long-term risks and costs of alternative diagnostic strategies to evaluate patients with chest pain

Technological advances in cardiac imaging have led to dramatic increase in test utilization and in cardiovascular healthcare costs [1‐3]. Cardiac imaging is a major contributor to rising healthcare costs with estimates of more than 9.3 million myocardial perfusion procedures performed in 2002 in the United States (US) [4] and a growth of 40% in the last 3 years [5]. Each test represents a cost, as well as a potential risk, as biohazards and downstream long-term costs linked to radiation exposure should also be considered [5].

Several current tests for the diagnosis of coronary artery disease are more expensive and more accurate than traditional ex-ECG [6‐8]. Little information exists to guide the clinician about which test to order or to inform policy makers about which tests represent the best value. Despite several meta-analyses, the effectiveness of these procedures, defined using prognostic value each test's, has been reported in several observational studies, but limited comparative data are available in similarly at-risk populations [9‐11]. Substantial cost saving could be realized if health care policies allocate resource use on the basis of both clinical outcomes and cost effectiveness data and it would be necessary a combined clinical and cost effectiveness-driven testing strategy in patients with suspected coronary artery disease. Ex-ECG, stress myocardial SPECT with thallium (Th) or technetium (Tc), and more recently, PhSE, ex-Echo and CA have been used to detect unstable angina (UA) and to identify, among patients referred for suggestive coronary artery disease, those at risk of coronary events [7]. Ex-ECG is considered the standard reference test to investigate the cause of chest pain that suggests coronary origin, where stress imaging testing (stress echocardiography, stress myocardial SPECT) and CA are the second and third choice [7, 12]. However, while the cost of ex-ECG is lower [12], the accuracy of other imaging tests is also claimed to be higher [6, 7, 9‐11]. This is a scenario where an economic evaluation could help in choosing a diagnostic test, since from the clinical point of view, is not enough that a test is marginally "better" than the other to justify its use: the extra-value should be proportional to the extra-cost and to the extra-risk.

In order to explore the relative merit of the tests in diagnosing coronary disease, we evaluated the overall clinical and economic outcomes of diagnostic strategies in similarly at-risk populations, i.e. in low- intermediate risk chest pain patients including downstream long-term risks and costs linked to radiation exposure by ionizing imaging testing. For this purpose, we investigated the cost-effectiveness of ex-ECG and four imaging modalities used in this setting in comparison with serum markers of myocardial injury. From a methodological viewpoint, we made an analysis to obtain an approximate estimate of the relative cost-effectiveness starting from the approximate relative costs of the tests and we evaluated the economic implications of the different strategies. A decision analytical model with six branches, each representing a treatment strategy for chest pain patients was created and the results of four studies, where different strategies were applied, have been analysed. For non-invasive strategies we selected studies including a wide number of patients and outcome analysis at six-twelve months follow-up.

The predictive accuracy was 83,1% for cTnI, 87% for cTnT 85,1% for ex-ECG, 93,4% for ex-Echo, 98,5% for PhSE, 89,4% for ex-SPECT-Tc and 18,7% for CA (Figure 2). In fact the strategy based on cTnI and cTnT test would have correctly identified the follow-up of 831 of 1.000 patients and 870 of 1.000 respectively versus 851 of 1.000 patients correctly identified by ex-ECG, 934 of 1.000 by ex-Echo, 985 of 1.000 by PhSE, 894 of 1.000 by ex-SPECT-Tc and 187 of 1.000 by CA. The costs of the strategy and the costs per patient correctly identified result $1.704.161 and $2.051 for cTnI, $1.814.482 and $2.086 for cTnT, $1.608.327 and $1.890 for ex-ECG, $750.282 and $803 for ex-Echo, $525.495 and $533 for PhSE, $1.359.953 and $1.521 for ex-SPECT-Tc ($1.634 including cost of extra risk of cancer) and $5.548.794 and $29.673 for CA ($29.999 including cost of extra risk of cancer) (Figure 3) (Table 2). The average relative cost-effectiveness of cardiac imaging compared with the PhSE equal to 1 (as a cost comparator), the relative cost of ex-Echo is 1.5×, of a ex-SPECT-Tc is 2,9× and 3.1× including cost for extra risk of cancer, of a ex-ECG is 3.5×, of cTnI is ×3.8, of cTnT is ×3.9 and of a CA is 56× and 56,3× including cost for extra risk of cancer (Figure 4).

As a leading cause of mortality and morbidity, CAD remains a field of innovation to improve health outcomes. In the US, there have been substantial increases in the utilization of procedures for the diagnosis and treatment of coronary artery disease from 1993 to 2001 and total costs of cardiac procedures nearly doubled [36, 37]. Increases in procedure rates over time continue to grow steadily and were dramatically pronounced for stress imaging studies, cardiac catheterizations, and coronary angioplasty. The increases were not uniform across procedures: there was a nearly 3-fold increase in the use of radionuclide imaging stress tests and a modest decline in nonimaging stress tests, percutaneous coronary angioplasty (PCI) doubled and coronary artery bypass grafting (CABG) was unchanged [37]. This increase is unlikely to be related to an increase in underlying disease prevalence, since the rate of hospitalization for AMI in the same population has been nearly constant [37, 38]. Rates of radionuclide imaging could suggest that the use has become much less focused and these imaging studies have become the standard of clinical practice in the risk stratification after AMI, PCI and CABG, although data to support their routine use in place of ex-ECG or stress echocardiography appear not yet conclusive [4, 12, 37, 38]. The impact may be minimal for many patients, deleterious for some patients, and costly for society. In the ideal healthcare system, to minimize waste and to maximize efficiency, it is essential to consider the appropriateness and outcomes of cardiac procedures.

The analysis is based on few studies performed in the ED and only one of these compared the different strategies in the same patients' population. However the results reflect accuracies and prognostic values indicated in previous studies and in meta-analyses performed in the overall low-intermediate risk chest pain patient population. The results of these studies could define new strategic approach with enormous medical, social and environmental implications.

Combined clinical outcomes and cost effectiveness-driven testing strategy favors the use of stress echocardiography as the first line diagnostic test and the driver to cardiac catheterization in low-intermediate risk chest pain patients. Widespread application of this approach in health care system policies could result in substantial cost saving, with a survival benefit of patients at-risk for future major cardiac events and reduction of downstream long-term risk and costs linked to radiation exposure. With all its limitations, this study just aims to provide an empirical evidence in support of the idea to favour and to incentive further investigations and extends multi-disciplinary empirical analyses in order to collect data useful for policy makers, for all the other stakeholders and, especially, for the society.