Severity, Seriousness and Causality

Part of Research Nurse (RN) Training: Recognizing Adverse Events.

About 2 minutes. Free, in your language, no account needed.

Why this matters

Three different words that people use interchangeably and that mean entirely different things on a trial.

Confusing them produces reports that say the wrong thing, sometimes with a reporting clock attached.

Severity

How bad it was. Usually mild, moderate or severe, or a numbered grading scale.

Severity is a clinical description. A severe headache is a bad headache. It is not necessarily a serious adverse event.

Seriousness

A regulatory category with a defined list. An event is serious if it results in death, is life-threatening, requires or prolongs hospitalization, causes persistent or significant disability, is a congenital anomaly, or is another important medical event by the same standard.

Seriousness is not about how unpleasant it was. A mild event can be serious. A severe event can be non-serious.

This distinction triggers the reporting clock, which is why it matters more than any other word in this module.

Causality

Whether the study intervention caused it. Usually assessed as related or not related, with gradations in between.

Causality is the investigator's assessment. Not yours. You may have a clear view and you may be right. You describe what you observed and you do not complete that field.

Why nurses get asked anyway

You saw it. You know the timing. You know what else the participant was taking.

Give the investigator that. "It started about four hours after the infusion, she has had it twice before, both times on infusion days" is enormously useful and is not a causality assessment.

In practice

A participant has severe nausea for a day, manages at home, and recovers.

Severity: severe. Seriousness: not serious, because it did not meet any of the listed criteria. Causality: the investigator decides.

Three fields, three different answers, none of them interchangeable.

What this looks like when it goes wrong

A nurse records a hospital admission as non-serious because the participant was only kept overnight for observation and was fine.

Hospitalization is on the seriousness list. The event should have started a 24-hour clock to the sponsor. It did not, because the wrong word was used.

The site is now late on a regulatory report and did not know it.

Key takeaways