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Glossary of Medical Writing Terms

Welcome to our Medical Writing Glossary. From common acronyms to complex scientific terms, we're here to demystify the language of medical writing.


Last updated: May 2024.

For more plain-language descriptions of medical terms, visit the EMA Medical Terms Simplifier.


Adverse Drug Reaction. An undesired harmful effect resulting from a medication or other intervention such as surgery or a medical device.


Adverse Event. Any untoward medical occurrence in a patient administered a drug, not necessarily causally related.


Complete Response. The complete disappearance of all signs of a disease or condition as confirmed by medical assessment or diagnostic tests, indicating successful and comprehensive treatment.


Data and Safety Monitoring Board. An independent committee responsible for reviewing and evaluating the safety and efficacy data from a clinical trial to ensure participant safety and data integrity.


European Quality of Life Five Dimension. A standardised instrument used to measure health-related quality of life developed by the EuroQol Group, consisting of five dimensions: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression, each with three levels of severity, providing a descriptive profile and a single index value for health status assessment.


Health Economics and Outcomes Research. A field of study that assesses the value of healthcare interventions by analysing their economic impact, effectiveness, safety, and patient outcomes.


Health-Related Quality of Life. An individual's perceived physical, mental, emotional, and social wellbeing related to their health status, encompassing factors such as functional status, symptom burden, psychological wellbeing, and overall satisfaction with life, influenced by both disease and treatment effects.


Intramuscular. Injection of medication into a muscle.


Institutional Review Board. A committee responsible for ensuring that research involving human subjects adheres to ethical standards and regulatory requirements.


Intravenous. Administration of medication or fluids directly into a vein.

NCT no.

The unique identification code given to each clinical study upon registration at The format is "NCT" followed by an 8-digit number.


Open Label Extension. Participants who completed the original trial continue receiving the investigational treatment with both the participant and researchers aware of the treatment being administered, aiming to gather long-term safety and efficacy data.


Over-The-Counter. Refers to medicines that can be bought without a prescription.


By mouth. Oral administration of medication.


As needed. Medication taken only when needed for symptom relief.


Patient Reported Outcomes. Health outcomes directly reported by patients about their symptoms, quality of life, functional status, etc.


Quality-Adjusted Life-Year. A measure used in health economics to quantify the value of healthcare interventions by combining both the quantity and quality of life gained from a particular treatment or intervention.


Partial Response. A medical condition or treatment outcome where there is an improvement in symptoms or disease status, but it is not complete or total.


Randomised Controlled Trial. The most rigorous type of clinical research with randomly assigned groups.


Response Evaluation Criteria in Solid Tumors. Provides standardised guidelines for measuring tumour response to treatment in oncology trials, aiding in assessing treatment effectiveness and facilitating comparison across studies.


Serious Adverse Event. An adverse event that results in death, is life-threatening, requires hospitalisation or leads to disability.


Subcutaneous. The tissue layer located just beneath the skin. Medications administered SC are injected into this layer using a needle, allowing for the gradual absorption of the medication into the bloodstream.


Treatment-Emergent Adverse Event. An undesirable medical occurrence or side effect that arises during or after the administration of a treatment, such as a medication or medical intervention, that was not present prior to the treatment.


Treatment-Emergent Adverse Event. Any negative or undesirable medical occurrence experienced by a patient that is determined to be related to the treatment they are undergoing, such as a medication, therapy, or medical intervention.

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