Definition

The date when a company first becomes aware of information that constitutes a valid, reportable adverse event case. This date starts the regulatory reporting clock.

Example

A sales rep receives verbal information about a serious adverse event on Monday. On Tuesday, they report it to drug safety. Day 0 is Monday - when the company (via its employee) first learned of it.

Regulatory source

ICH E2D Section 4.3, EU GVP Module VI

Common mistakes

Setting Day 0 as when the drug safety department receives the case, rather than when any company employee first learns of it.

Inspector question

If a sales representative learns of a serious adverse event on Friday but doesn't report it until Monday, what is Day 0? How do you train field staff on this?

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