When formulating the research question it is necessary to meet three criteria:
- The question should be economically important.
- The question should be phrased in a way that takes both cost and outcome into consideration.
- The question should clearly state the viewpoint of the economic evaluation.
Finally the hypothesis of the economic evaluation should also be stated clearly.
Selection of Statistical Tests
The statistical tests which are used should match the data set they are used on as there are a lot of tests which differ in target size (e.g. variance or average). Please regard this Overview of statistical tests. The chosen test should be justified for better traceability. This verifies the usability of the test. Normally the choice should be made before collecting data, a minimum sample size is given by the choice of the test. As this is a complex process, it is recommended to contact a biometrician if necessary.
The details of the statistical tests should be given as well as the confidence intervals of the observed variables.
Searching for Data
Depending on which source the evaluation relies, different questions arise and several aspects have to be considered.
Search for trials and overviews
Clinical trials, i.e. their results, are often published in renowned journals. Search for such publications in databases like
When searching for an overview use the aforementioned sources. Though a good and reliable source for overviews is the Cochrane Collaboration.
The Cochrane Library hosts all systematic reviews executed under the conditions and rules of the Cochrane Collaboration.
If possible only rely on clinical trials which are randomized, double-blinded and controlled. This type of study design is called gold standard and ensures highest internal validity.
In order to judge the quality for publications it might be useful to allocate the Jadad score.
The study protocol of a clinical trial should report the design and result of the study, method of allocation of subjects, effect size with confidence intervals, whether it is an intention-to-treat analysis or an evaluable cohort analysis. If it is a trial with placebo control take into account to mention suitable active comparators.
Overviews should report details about the method of synthesis or meta-analysis, search strategy, criteria for inclusion or exclusion of studies.
Costs: What should be considered?
All kind of clinical procedures of a patient should be reported. But not all procedures take place in a regular clinical care (efficacy) therefore it should be considered whether all procedures in the trial are characteristic of normal clinical practice (effectiveness).
Estimates of resource quantities should be based on data of real patients collected from medical records. Regarding the German health care system estimates of resources can be either based upon Microcosting or Top-down-approach . The prices of the ressources can be obtained from the finance departments of particular institutions or from national statistics but it should be considered that charges or fees can differ from real costs. The evaluation should comment on the extent of which using charges may bias their estimates.
Where to search for prices of resources in Germany?
Currency conversion should be based on real purchasing power, rather than financial exchange rates, which fluctuate according to money market changes.