Outcome switching

Outcome switching is to the practice of changing the primary or secondary outcomes of a clinical trial after its initiation. Outcome switching can undermine the reliability of the trial, for instance when outcome are switched after researchers have become aware of the data. It can lead to bias in terms of benefits and harms. For example, when the findings using the original protocol were statistically insignificant, a research may cherry pick a new outcome measure that is statistically significant. Incomplete or misleading reporting of outcomes is an example of unethical research practice.

Primary outcomes for clinical trials need to be defined upfront to prevent a biased selection of outcomes. Some medical journal require adherence to the Consolidated Standards of Reporting Trials (CONSORT), which requires authors to document any deviations from the initial study protocol and explain why changes were made. For instance, JAMA and the British Medical Journal require inclusion of the CONSORT checklist.

Despite problems with outcome switching, the practice is common. Changes in primary outcome metrics are present in nearly one in three studies. Outcome switching also occurs frequently in follow-up studies. In oncology, outcome switching is more common in studies with a male first author, and in studies funded by non-profits. One study analysed outcome switching in five top medical journals, writing letters for each misreported trial outcome. Journal editors and clinical trial authors typically responded dismissively when concerns were raised, misrepresenting ethical standards and including ad hominem attacks.

References

Research ethics Clinical research ethics