Adverse events (AE), treatment emergent adverse events (TEAE), and adverse drug reaction (ADR)

There is some debate and inconsistencies regarding the definition of Adverse Drug Reactions. If you call it an adverse event, you may not have a culprit drug in mind, whereas calling it an adverse drug reaction is already linking it to a suspected drug. Regardless of whether or not there is a suspected drug, an AE or an ADR is commonly defined as any adverse change in health or un-desired "side-effect" that occurs in a person while on a medical treatment (for example, drug or device) or within a pre-specified period after treatment is complete. Not every adverse event is causally related to the treatment or test being studied. However, regardless of causality, people who experienced adverse reactions, or their doctors, are encouraged to report these events to the FDA or the relevant regulatory authority in the country where the drug or device is registered.

Adverse event (AE) is any untoward medical occurrence including:

• undesirable signs & symptoms
• disease or accidents
• abnormal lab finding (leading to dose reduction/discontinuation/intervention)

during treatment with a pharmaceutical product in a patient or a human volunteer that does not necessarily have a relationship with the treatment given.
Adverse events is typically collected after signing the informed consent form and could be related or unrelated to the study drug.
Adverse drug reaction (ADR) is defined as:

• For approved pharmaceutical product: a noxious and unintended response at doses normally used or tested in humans;
• for a new unregistered pharmaceutical product: a noxious and unintended response at any dose.

WHO defines "a response to a drug which is noxious & unintended and which occurs at doses normally used for prophylaxis diagnosis or therapy of a disease or for modification of a physiological function.
The difference between AE and ADR is that AE event does not imply causality, but for ADR, a causal rule is suspected.

Another confusion is about the term 'treatment-emergent adverse event (TEAE)'. A treatment-emergent adverse event is defined as any event not present prior to the initiation of the treatments or any event already present that worsens in either intensity or frequency following exposure to the treatments. Since the starting point for AE collection is the signing of the informed consent, not the start of the study treatment, there are some adverse events occurred prior to the initiation of the study treatment. These AEs may be called "baseline-emergent adverse event" which defined as any event which occurs or worsens during the staged screening process (after informed consent) including the randomization visit. It is common to have separate summaries for AEs occurred piror to the initiation of the treatment and AEs occurred after the initiation of the treatment (ie, summary of treatment emergent adverse events).

I was asked about a programming practice to define the TEAE used in some companies. For any AE with onset date/time after the first study drug administration date/time,they compare if there is a same AE with the same severity. If yes, AE is not counted as TEAE (even though the onset date/time is after the study drug administration). For example, a subject has a mild headache 30 days after using the study medication and subjects also has a mild headache event before using the study medication,the programming will identify this event as non treatment emergent. However I think this is wrong these are two distinct events and the second one should be counted as treatment emergent AE.

The TEAE is different from the drug-related adverse events. While the treatment emergent AEs refers to adverse events temporally related to the study treatment, the drug-related AEs refers to the causality assessment by the investigator.