Look out for treatment comparisons that are sensitive to assumptions that are made.
Sometimes treatment claims depend on putting together different types of evidence and making assumptions. For example, a claim about the effects of using a screening test may depend on how accurate the test is, assumptions about how the test results will affect treatment choices, and evidence of the effects of the treatment.
For example, a comparison of the effects of different tests (e.g. two different tests for detecting cervical cancer) might require an assumption about what actions people will take based on the test results (e.g. how women with a ‘positive’ test will be treated). If it is uncertain what action people will take, it is important to consider how changing that assumption might affect the results of the comparison.
REMEMBER: Whenever treatment claims depend on assumptions, think about whether the assumptions are well-founded and how sensitive the results are to changes in the assumptions that were made.