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Cost-effectiveness of exercise 201Tl myocardial SPECT in patients with chest pain assessed by decision-tree analysis |
Kosuda S, Ichihara K, Momiyama Y, Ohsuzu F, Kusano S |
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Record Status 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. Health technology Exercise 201 TI myocardial SPECT in outpatients with angina-like chest pain.
Economic study type Cost-effectiveness analysis.
Study population For the single study the population consisted of male and female outpatients with angina-like chest pain. For the modelling part of the analysis three hypothetical patient groups (1,000 in each) were used for each diagnostic strategy. These patients were assumed to have angina-like chest pain based on hardening of the coronary arteries. Patients with a suspected history of acute myocardial infarction (AMI) were excluded.
Setting The setting was a hospital.
Dates to which data relate The effectiveness data came from a single study conducted between July 1997 and December 1997 and from studies published between 1983 and 1998. The cost data relate to the single study period July 1997 to December 1997. The price year was not stated.
Source of effectiveness data The effectiveness data came from a single study and a review of previously published studies.
Link between effectiveness and cost data The cost data for the single study were collected retrospectively from the same sample.
Study sample 106 (73 male, 33 female) outpatients who visited the National Defence Hospital in Japan between July and December 1997 with complaints of chest pains. The mean age of the study group was 62.5 years (range: 29 - 84). They were suspected of suffering from angina-like chest pain based on such tests as abnormal exercise ECG test and went through exercise 201 TI myocardial SPECT evaluation. No power calculations were conducted on the sample size.
Study design The study took the form of a cohort study carried out at a single centre.
Analysis of effectiveness The type of analysis of effectiveness (intention to treat or treatment completers only) was not stated. The outcomes assessed were the sensitivity and specificity of exercise 201 TI myocardial SPECT. The prevalence of angina due to the presence of stenosis was also assessed from the results.
Effectiveness results Of 106 patients, 35 were diagnosed as suffering from angina (prevalence 33%) due to having more than one significant stenosis and 29 patients were found to have no significant stenosis by the following CAG test. 42 patients did not receive CAG as their chest pains either disappeared or reduced during follow-ups. The sensitivity and specificity of exercise 201 TI myocardial SPECT were calculated as 94.3% (33/35) and 83.1% (59/71), respectively.
Clinical conclusions The prevalence, sensitivity and specificity findings in this single study were used to populate the probabilities used in the decision tree.
Modelling Decision trees were used for a simulation of the cost-effectiveness of three different strategy groups: SPECT group which received exercise 201 TI myocardial SPECT prior to CAG, a CAG group which received CAG without SPECT, and a follow-up group which received only follow-ups without either of the diagnostic examinations. Based on the data from a single study and the data from published studies, probabilities after chance nodes were calculated and the number of cases at the pay-off (terminal) nodes were calculated using Bayesian techniques.
Outcomes assessed in the review The outcomes assessed from the literature review were angina prevalence, SPECT sensitivity and specificity, mortality of CAG and Percutaneous Transluminal Coronary Angioplasty (PTCA), PTCA success rate and restenosis rate, cardiac event and death rate for normal SPECT patients and those with abnormal scans.
Study designs and other criteria for inclusion in the review Sources searched to identify primary studies Criteria used to ensure the validity of primary studies Methods used to judge relevance and validity, and for extracting data Number of primary studies included 10 primary studies were included.
Methods of combining primary studies The narrative method was used to combine results.
Investigation of differences between primary studies Results of the review Angina prevalence ranged from 26% to 80% for patients who underwent major non-cardiac surgery and from 22% to 47% for patients with chest pain in the emergency department.
SPECT sensitivity and specificity were 95% (range: 45 - 95%) and 85% (range: 48 - 90%), respectively.
CAG mortality was 0.1% and PTCA mortality was 0.6%.
PTCA success rate was 100% (above 95%) and the restenosis rate was 30% (range: 17 - 47%).
The cardiac event rate among normal SPECT patients was 8.3%. The cardiac event rate among patients with an abnormal scan was 62.9%. The cardiac death rate among normal SPECT patients was 1.7% and that among patients with an abnormal scan was 20.8%.
These data were also used as part of the baseline input parameters for the decision tree.
Measure of benefits used in the economic analysis The measures of benefit used were the number of cardiac events and cardiac deaths. Data for these were derived from a previous study conducted at the same institution.
Direct costs The direct costs used were the mean costs calculated based on the receipts collected at the hospital for the sample studied in a single study (actual data derived from the authors' hospital). The costs for 201 TI myocardial SPECT were Y75,600, those for CAG (including such costs as hospitalisation, ECG, heart rate observation and film costs) were Y346,190, and those for PTCA plus CAG (including such costs as hospitalisation, ECG, heart rate observation and film costs) were Y1,264,045. Quantities and costs were not reported separately. Discounting was not relevant due to the short period of analysis: less than 1 year. The price year was not stated but is likely to have been 1997, the date of the primary study.
Statistical analysis of costs No statistical analysis was carried out.
Indirect Costs Indirect costs were not included.
Sensitivity analysis To test for variability in the data, one-way sensitivity analysis was carried out using restenosis rates of 20%, 30% (baseline) and 40% to determine the effect on cost/patient outcomes for each of the three strategies examined.
Estimated benefits used in the economic analysis The SPECT strategy resulted in 583 less cases of CAG. The numbers of cardiac events for the CAG, follow-up, and SPECT groups were 56, 264, and 65, respectively. The number of cardiac deaths were 15, 81, and 17, respectively.
Cost results The mean costs for one patient in the CAG, follow-up and SPECT groups were Y848,801, Y302,107, and Y710,640, respectively. Although the restenosis rate was set at 30% in the simulation, changes in this rate were found to affect the above mean costs. In the case of 20% restenosis, the costs for CAG, follow-up and SPECT groups were Y800,769, Y279,354, and Y663,871, respectively. In the case of 45% restenosis the costs were Y919,588, Y337,500, and Y777,635, respectively.
Synthesis of costs and benefits Use of exercise 201 TI myocardial SPECT increases cardiac events by 0.9% and increases cardiac deaths by 0.2% but it reduces the number of CAG procedures by 50.3% and reduces costs by 13.8 x 10^4 Yen/patient in comparison with the use of CAG only.
Authors' conclusions The exercise 201 TI myocardial SPECT procedure for patients with chest pain has the potential to reduce health care costs in Japan, is associated with an increase in cardiac events and deaths, but has the benefit of reducing the number of CAG procedures, which also carry risks for the patient.
CRD COMMENTARY - Selection of comparators The rationale for the choice of comparators was clear and was appropriately justified by the authors. The motivation behind the study was to assess the feasibility of reducing costs for the analysis of the study population using a clinically acceptable alternative.
Validity of estimate of measure of effectiveness The effectiveness (sensitivity and specificity) of the SPECT and prevalence of angina due to stenoses were appropriately determined for the study institution using sound methods and these figures were validated by an analysis of the literature. However, the authors also point out that these values (used in the modelling) are likely to vary from institution to institution. This needs to be borne in mind when considering the validity of these results for other settings. The reliability of the results could have been enhanced by sensitivity analyses around these parameters (restenoses was examined in this manner) and this would also have increased the generalisability of the results.
Validity of estimate of measure of benefit The measures used (cardiac events and cardiac death) were appropriate for the study and were derived using credible methods within the modelling. Data to derive these benefits were synthesised using the findings of the present study and a previous study conducted at the authors' institution.
Validity of estimate of costs The validity of the cost estimates is likely to be high as they were based on actual data, although it should be noted that no sensitivity and specificity analyses were reported. This may be a feature of the Japanese health care system that tends to fix unit costs for diagnostic procedures centrally (and therefore variability is not an issue). Costs were also compared with American data.
Other issues The authors noted that there would be variations from setting to setting in terms of prevalence, sensitivity and specificity. The issue of treatment alternatives for those requiring corrective procedures for stenoses also has to be considered. The authors used PTCA as a reference procedure but other alternatives such as CABG ought to be included in future analyses, as the authors noted. In this sense the issue of generalisability was addressed. The authors also stressed the importance of taking into account various risk factors associated with the patients (such as age, sex, and coronary risk) which they intend addressing in future studies.
Implications of the study The findings give support for economic benefits to be realised from the introduction of SPECT, but there is a slight increase in adverse health outcomes. At the same time the intervention will benefit patients in the avoidance of risk, and invasive procedures such as CAG. Future studies may be able to address the various limitations of the present study as identified in the commentary above.
Bibliographic details Kosuda S, Ichihara K, Momiyama Y, Ohsuzu F, Kusano S. Cost-effectiveness of exercise 201Tl myocardial SPECT in patients with chest pain assessed by decision-tree analysis. Kaku Igaku The Japanese Journal of Nuclear Medicine 1999; 36(7): 715-723 Indexing Status Subject indexing assigned by NLM MeSH Chest Pain /radionuclide imaging; Coronary Angiography /economics; Cost-Benefit Analysis; Decision Trees; Exercise Test; Health Care Costs; Heart /radionuclide imaging; Humans; Models, Statistical; Radiopharmaceuticals; Sensitivity and Specificity; Thallium Radioisotopes; Tomography, Emission-Computed, Single-Photon /economics AccessionNumber 22000006051 Date bibliographic record published 31/10/2001 Date abstract record published 31/10/2001 |
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