AHRQ Patient Safety Network

Glossary
Close Window

Definitions abound in the medical error and patient safety literature, with subtle and not-so-subtle variations in the meanings of important terms. We have tried to adopt the most straightforward terminology, with definitions that enjoy the widest use.


Adverse Drug Event (ADE):
An adverse event (i.e., injury resulting from medical care) involving medication use.

Examples:
  • anaphylaxis to penicillin
  • major hemorrhage from heparin
  • aminoglycoside-induced renal failure
  • agranulocytosis from chloramphenicol
As with the more general term adverse event, the occurrence of an ADE does not necessarily indicate an error or poor quality of care. ADEs that involve an element of error (either of omission or commission) are often referred to as preventable ADEs. Medication errors that reached the patient but by good fortune did not cause any harm are often called potential ADEs. For instance, a serious allergic reaction to penicillin in a patient with no prior such history is an ADE, but so is the same reaction in a patient who has a known allergy history but receives penicillin due to a prescribing oversight. The former occurrence would count as an adverse drug reaction or non-preventable ADE, while the latter would represent a preventable ADE. If a patient with a documented serious penicillin allergy received a penicillin-like antibiotic but happened not to react to it, this event would be characterized as a potential ADE.

An ameliorable ADE is one in which the patient experienced harm from a medication that, while not completely preventable, could have been mitigated. For instance, a patient taking a cholesterol-lowering agent (statin) may develop muscle pains and eventually progress to a more serious condition called rhabdomyolysis. Failure to periodically check a blood test that assesses muscle damage or failure to recognize this possible diagnosis in a patient taking statins who subsequently develops rhabdomyolysis would make this event an ameliorable ADE: harm from medical care that could have been lessened with earlier, appropriate management. Again, the initial development of some problem was not preventable, but the eventual harm that occurred need not have been so severe, hence the term ameliorable ADE.

Close Window