ICH E2A (Clinical Safety Data Management: Definitions and Standards for Expedited Reporting)

ICH E2A’s full formal title is Clinical Safety Data Management: Definitions and Standards for Expedited Reporting, and the version in force is the Current Step 4 text dated 27 October 1994. Two things surprise most first-time readers. The acronym SUSAR appears nowhere in the guideline — E2A’s own phrase is “serious, unexpected adverse drug reactions,” and the SUSAR label was coined later, in European law. And E2A is not a procedures manual: it fixes what the safety words mean and when the clock starts, then leaves each region to legislate the mechanics.

Why there is no E2A(R1)

The history table printed in the guideline records three entries: Step 2 release for consultation on 24 June 1993; Step 4 approval, recommended for adoption to the three ICH regulatory bodies, on 27 October 1994; and a November 2005 re-codification that changed the document code, not the content. Unlike ICH E6(R3), E2A has never been reopened. When a source calls it “outdated,” what is meant is that operational detail migrated outward — to E2B for electronic case-report data elements, E2D for post-approval cases, E2F for the Development Safety Update Report — while E2A’s definitions were left alone, because rewriting them would unsettle every regulation that cites them.

The definitions, as the Step 4 text words them

An adverse event is “any untoward medical occurrence in a patient or clinical investigation subject administered a pharmaceutical product and which does not necessarily have to have a causal relationship with this treatment.” An unexpected adverse drug reaction is “an adverse reaction, the nature or severity of which is not consistent with the applicable product information (e.g., Investigator’s Brochure for an unapproved investigational medicinal product).” Note the pairing E2A chose: nature or severity. US law later phrased the same test as specificity or severity relative to the investigator brochure (21 CFR 312.32(a)), which is why the two frameworks can diverge on a reaction that is listed, but not at the specificity observed.

The seriousness criteria cover an occurrence that at any dose results in death, is life-threatening, requires inpatient hospitalisation or prolongation of existing hospitalisation, results in persistent or significant disability/incapacity, or is a congenital anomaly/birth defect. Two attached clarifications get dropped constantly. “Life-threatening” means the patient was at risk of death at the time of the event, not that it might have caused death had it been more severe. And “serious” is not “severe”: severity is intensity, whereas “seriousness (not severity) serves as a guide for defining regulatory reporting obligations.” Important medical events meeting none of the five criteria may still warrant expedited reporting on medical and scientific judgement — prose, not a sixth bullet, which is why it is missed. See serious adverse event (SAE).

The 7-day and 15-day clocks

Fatal or life-threatening unexpected ADRs: as soon as possible but no later than 7 calendar days after first knowledge by the sponsor that a case qualifies, “followed by as complete a report as possible within 8 additional calendar days.” All other serious, unexpected ADRs: no later than 15 calendar days after first knowledge that the case meets the minimum criteria — an identifiable patient; a suspect medicinal product; an identifiable reporting source; and an event identifiable as serious and unexpected, with a reasonable suspected causal relationship in clinical-investigation cases. An incomplete case is still filed on time, with follow-up “actively sought and submitted as it becomes available.”

On causality E2A is more permissive than many sponsors assume: cases judged by either the reporting health care professional or the sponsor to have a reasonable suspected causal relationship qualify as ADRs, “reasonable” meaning “there are facts (evidence) or arguments to suggest a causal relationship.” One investigator’s suspicion starts the clock. US practice under 21 CFR 312.32 diverges — there the sponsor determines whether information qualifies — as set out on the SUSAR and IND safety report entries.

Dechallenge, rechallenge, and what E2A omits

Each word appears exactly once, in Attachment 1’s list of desirable data elements — “Dechallenge and rechallenge information” — beside onset time, duration, setting and outcome. E2A defines neither. Readers hunting an E2A definition usually want causality-assessment method, and there E2A states plainly that no standard international nomenclature exists: it lists the competing vocabularies (certainly, definitely, probably, possibly or likely related) and endorses no scale. It nominates the CIOMS-I form as the accepted reporting standard while insisting data elements matter more than format, and treats code-breaking after a serious event in a double-blind study as a decision to settle in advance — see blinding and masking in clinical trials.

Related terms

• SUSAR (Suspected Unexpected Serious Adverse Reaction) — the three-part test E2A’s definitions cascade into.
• Serious adverse event (SAE) — the seriousness criteria at case level.
• Adverse event (AE) — the causality-free starting category.
• IND safety report — the US implementation of the same 7/15-day structure.
• Development Safety Update Report (DSUR) — the ICH E2F aggregate report.
• ICH (International Council for Harmonisation) — the body and its stepwise process.
• Good Pharmacovigilance Practices (GVP) — the EU post-authorisation equivalent.