Most of use AE(Adverse event), ADE(Adverse drug event) and ADR(Adverse drug reaction) interchangeably, but they have different definitions according to pharmacovigilance.
Adverse event : An Adverse Event is any untoward medical occurrence that happens while a patient is taking a drug, but it does not necessarily have a causal relationship with the treatment.
- Note : Drug may or may not have causal relationship with the outcome.
- Example : A patient participating in a clinical trial for a new cholesterol medication falls from the steps and breaks their hand. Because the injury is just temporarily associated with the drug trial and not caused by the drug itself it is reported as an Adverse event.
Adverse Drug Event : Any injury resulting from the use of the drug. This includes ADRs, but also includes medication errors, overdose and harm from inappropriate use or discontinuation.
- Note : It is caused by drug but also includes harm caused due to medication errors, drug interactions and overdose. It can be preventable or non-preventable.
- Example(Preventable) : A nurse accidentally ingest double dose of a blood thinner to the patient and the patient subsequently develops internal bleeding.
- Example(Non-preventable) : A patient takes the correct dose of an anti coagulant and significantly develops internal bleeding.
Adverse Drug Reaction : A response to a drug which is noxious and unintended and which occurs at doses normally used in humans for prophylaxis, diagnosis or therapy.
- Note : There is a causal relationship between the clinical outcome and the drug.
- Example : A patient is taking standard dose of antibiotic and develops rash.
| Term | Is it caused by a drug ? | Does it include medication errors? |
|---|---|---|
| Adverse Event(AE) | Maybe/unproven(just a timeline link) | No |
| Adverse Drug Event(ADE) | Yes(caused by the drug or its administration) | Yes |
| Adverse Drug Reaction(ADR) | Yes(Directly caused by the drug) | No(only occurs at standard doses) |
| Scenario | Classification | Why? | ||
|---|---|---|---|---|
| Patient A : The nurse misreads the chat and gives the patient double dose of the blood thinner that is prescribed and patient develops internal bleeding. | ADE | The harm is related to the drug, but it is caused by preventable medication error. It cannot be an ADR because the dose is wrong. | ||
| Patient B : The patient receives the standard dose of antibiotic and develops allergic reaction | ADR(Which is also a type of ADE) | The harm is directly caused by the drug itself under normal standard dose. There was no error. |
Why it is important to known the difference :
- Helps ensure accurate pharmacovigilance reporting.
- Improves patient safety by identifying true cause.
- Helps evaluate risk-benefit profile of medicined through out their lifecycle.
- Supports the development of risk minimization and patient safety strategies.
- Strengthens post-marketing surveillance and public health monitoring.
- Assists in detecting and preventing medication errors.
- Improves quality of clinical documentation and medication review processes.
Final Takeaway :
Not every adverse event(AE) is caused by a drug, not every adverse drug event(ADE) is an adverse drug reaction(ADR), but every ADR is considered an ADE. Understanding these distinctions is essential for patient safety, accurate reporting and effective pharmacovigilance.
Have you ever confused AE, ADE and ADR? Share your thoughts or experiences?
MBH/PS