Glossary of terms used in Pharmacovigilance (PART 4 FINAL)

Glossary of terms used in Pharmacovigilance (PART 4 FINAL)

Omega (Ω)

A measure of disproportionate reporting for drug-drug-ADR triplets in ICSR databases, designed to highlight potential signals of drugdrug interactions. Just like the more established disproportionality measures for drug-ADR pairs, Ω is based on a contrast between the observed and expected number of reports. A positive Ω indicates higher reporting than expected.

OTC (Over The Counter) medicine

Medicinal product available to the public without prescription.


Software developed by UMC for collection and analysis of data in relation to vaccinations in a

pandemic situation.

Periodic Safety Update Report


A systematic review of the global safety data which became available to the manufacturer of a marketed drug during a specific time period. Produced in an internationally agreed format.


Study of the use and effects of drugs in large populations. Also see Epidemiology.


Study of the uses, effects and modes of action of drugs.


The science and activities relating to the detection, assessment, understanding and prevention of adverse effects or any other drugrelated problem.


Characteristic deformity caused by exposure to thalidomide in the womb, also very rarely occurring spontaneously. Meaning: limbs like a seal.


Western-style, scientific treatment using plant extracts or materials.


An inactive substance (often called a sugar pill) given to a group being studied to compare results with the effects of the active drug.


The concomitant use of more than one drug, sometimes prescribed by different practitioners.


The stage when a drug is generally available on the market.

Predisposing factors

Any aspect of the patient’s history (other than the drug) which might explain reported adverse events (genetic factors, diet, alcohol consumption, disease history, polypharmacy or use of herbal medicines, for example).


The stage before a drug is available for prescription or sale to the public.

Prescription Event Monitoring (PEM)

System created to monitor adverse drug events in a population. Prescribers are requested to report all events, regardless of whether they are suspected adverse events, for identified patients receiving a specified drug. Also more accurately named Cohort Event Monitoring.

Prescription Only Medicine (POM)

Medicinal product available to the public only on prescription.


Number of existing cases of an outcome in a defined population at a given point in time.


Prevention or protection.

Rational drug use

An ideal of therapeutic practice in which drugs are prescribed and used in exact accordance with the best understanding of their appropriateness for the indication and the particular patient, and of their benefit, harm effectiveness and risk.


The point at which a drug is again given to a patient after its previous withdrawal – also see


Record linkage

Method of assembling information contained in two or more records, eg in different sets of medical charts, and in vital records such as birth and death certificates. This makes it possible to relate significant health events that are remote from one another in time and place.

Reference risk

Risk in a population of unexposed persons; also called baseline risk. Reference risk can be measured over time (incidence) or at a given time (prevalence). The unexposed population refers to a reference population, as closely comparable to the exposed population as possible, apart from the exposure. 

Regulatory authority

The legal authority in any country with the responsibility of regulating all matters relating to drugs.

 Relative risk

Ratio of the risk in an exposed population (absolute risk) and the risk in an unexposed population (reference risk). Relative risk is the result of a relative comparison between outcome frequency measurements, e.g. incidences.


The probability of harm being caused; the probability (chance, odds) of an occurrence.

Serious Adverse Event or Reaction

A serious adverse event or reaction is any untoward medical occurrence that at any dose:

  • results in death
  • requires inpatient hospitalisation or
  • prolongation of existing hospitalisation
  • results in persistent or significant
  • disability/incapacity
  • is life-threatening

To ensure no confusion or misunderstanding of the difference between the terms ‘serious’ and ‘severe’, the following note of clarification is provided:

The term ‘severe’ is not synonymous with serious. In the English language, ‘severe’ is used to describe the intensity (severity) of a specific event (as in mild, moderate or severe); the event itself, however, may be of relatively minor medical significance (such as severe headache). Seriousness (not severity) which is based on

patient/event outcome or action criteria serves as guide for defining regulatory reporting obligations.

Side effect

Any unintended effect of a pharmaceutical product occurring at normal dosage which is related to the pharmacological properties of the drug.


Reported information on a possible causal relationship between an adverse event and a drug, the relationship being unknown or incompletely documented previously. Usually more than a single report is required to generate a signal, depending upon the seriousness of the event and the quality of the information. The publication of a signal usually implies the need for some kind of review or action.

Summary of Product Characteristics


A regulatory document attached to the marketing authorization which forms the basis of the product information made available to prescribers and patients.

Spontaneous reporting

System whereby case reports of adverse drug events are voluntarily submitted from health professionals and pharmaceutical manufacturers to the national regulatory authority. Also see ICSR.


Drug prescribed in the 1950s as a mild sleeping pill and remedy for morning-sickness for pregnant women. Led to serious birth defects and the start of modern pharmacovigilance. Returning to favour in treatment of serious diseases such as cancer and leprosy.

Traditional medicines

Traditional medicine is the sum total of the knowledge, skills, and practices based on the theories, beliefs, and experiences indigenous to different cultures, whether explicable or not, used in the maintenance of health as well as in the prevention, diagnosis, improvement or treatment of physical and mental illness. Also see Allopathic medicine. 

Unexpected adverse reaction

An adverse reaction, the nature or severity of which is not consistent with domestic labelling or market authorization, or expected from characteristics of the drug.


The name of the WHO Global ICSR Database.


VigiFlow is a complete ICSR management system created and maintained by the UMC. It is web-based and built to adhere to the ICH-E2B standard. It can be used as the national database for countries in the WHO Programme as it incorporates tools for report analysis, and facilitates sending reports to VigiBase.


Sharepoint based conferencing facility, exclusive to member countries of the WHO Programme for International Drug Monitoring for fast communication of topical pharmacovigilance issues.


A statistical tool within VigiSearch with vast statistical material calculated for all Drug-ADR pairs (combinations) available in VigiBase. The main features include the disproportionality measure (IC value) stratified in different ways and useful filter capabilities.


A search service for accessing ICSRs stored in the VigiBase database offered by the UMC to national pharmacovigilance centres and other third-party inquirers.


Terminology for coding clinical information in relation to drug therapy. WHO-ART is maintained by UMC.

WHO Drug Dictionary (WHO DD)

The WHO Drug Dictionary is an international classification of drugs providing proprietary and on-proprietary names of medicinal products used in different countries, together with all active ingredients.



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