Protocol deviation
In Running the trial
Also known as: protocol violation, protocol non-compliance
A protocol deviation is any departure from what the approved protocol says should happen. Deviations range from a visit a few days outside its window to enrolling someone who did not meet the criteria. Important deviations — those affecting participant safety, rights, or the reliability of the data — must be recorded, reported, and acted on.
Example
A blood sample taken on day 32 when the protocol specifies day 28 plus or minus 3 days is a visit-window deviation. It is documented even if it has no clinical consequence.
Common questions
- What is the difference between a protocol deviation and a protocol violation?
- Many organizations use deviation for any departure and reserve violation for one that is serious — affecting safety, rights, or data reliability. The terms are not used identically everywhere, so the local SOP definition is what counts.
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