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National Information Center on Health Services Research and Health Care Technology (NICHSR)

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Health Economics Information Resources: A Self-Study Course

Module 4: An Introduction to the Principles of Critical Appraisal of Health Economic Evaluation Studies

Sample critical appraisal exercise: An economic evaluation of thrombolysis in the community 

1. Was a well-defined question posed in answerable form?

1.1. Did the study examine both costs and effects of the service(s) or program(s)?

Yes.

1.2. Did the study involve a comparison of alternatives?

Yes.

1.3. Was a viewpoint for the analysis stated and was the study placed in any particular decision-making context?

Yes, the viewpoint is given as the UK National Health Service (the purchaser and provider of health care).

2. Was a comprehensive description of the competing alternatives  given (i.e., can you tell who did what to whom, where, and how often)?

2.1. Were there any important alternatives omitted?

Possibly. There may be other forms of thrombolysis or other forms of intervention, such as surgery.

2.2. Was (should) a do-nothing* alternative be considered?

No, acute myocardial infarction will always be treated if possible.

* A ‘do nothing’ alternative might be, for example, the introduction of a diagnostic test for a disease/condition for which there has been no previous definitive diagnostic test.

3. Was the effectiveness of the program or services established?

3.1a. Was this done through a randomized controlled trial (RCT)?

Yes, the effectiveness data came from a single RCT.

3.1b. If so, did the trial protocol reflect what would have happened in regular practice?

 Yes, the trial protocol reflected what would happen in regular practice for the setting, but normally streptokinase is the standard hospital therapy.

The study states that before the start of the trial the general practitioners involved routinely attended patients with suspected AMI. The follow-up of 1, 2.5, and 4 years provides useful information.

3.2. Was the effectiveness established through an overview of clinical studies?

No. Effectiveness is based on data from a single RCT.

3.3. Were observational data or assumptions used to establish effectiveness? If so, what are the potential biases in results?

No observational data was used – the effectiveness data was from GREAT alone with the assumption that GP attends ALL suspected AMI cases and that they (the GP) arrive within usual time of patient traveling to hospital, assessment for treatment etc.

Anistreplase, the drug used in GREAT, has the same effectiveness as streprokinase, the drug used in hospitals.

4. Were all the important and relevant costs and consequences measured accurately in appropriate physical units (e.g., hours of nursing time, number of physician visits, lost work-days, gained life years)?

4.1. Was the range wide enough for the research question at hand?

No, long-term costs and consequences other than survival not considered.

4.2. Did it cover all relevant viewpoints? (Possible viewpoints include the community or social viewpoint, and those of patients and third-party payers. Other viewpoints may also be relevant depending upon the particular analysis.)

Yes. The relevant viewpoint here is the health care purchaser, in this case the NHS. Only treatment costs are included in analysis. There are no direct patient costs or ‘other sector’ costs. Indirect costs, e.g., productive costs/activity (e.g., housework) not included.

4.3. Were the capital costs, as well as operating costs, included?

Yes. The capital costs of the ECG and defibrillator were included.

5. Were costs and consequences measured accurately in appropriate physical units (e.g., hours of nursing time, number of physician visits, lost work-days, gained life years)?

5.1. Were any of the identified items omitted from measurement? If so, does this mean that they carried no weight in the subsequent analysis?

Although not individually itemized, there is nothing to suggest that identified items were omitted from measurement, i.e., drug costs, labor costs, capital costs. Every patient has same unit cost applied.

5.2. Were there any special circumstances (e.g., joint use of resources) that made measurement difficult? Were these circumstances handled appropriately?

For the purposes of the trial it was accepted that all the GPs involved had undergone the appropriate training and acquired an ECG and defibrillator - these already attend suspected AMI cases.

The cost in terms of length of time of GP attendance are included in the low cost estimate and this is made explicit, as is the GP time cost and capital cost included in the high estimate, i.e., special circumstances where the GP does not already have these capital items.


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