The importance of pharmacovigilance the ongoing assessment of the safety of a marketed medicine has been increasingly appreciated in recent years, owing in part to high-profile safety issues with widely used drugs. In response, strategies to improve the collection, integration and analysis of data related to post-marketing drug safety are being initiated or enhanced. The key tools that are available for pharmacovigilance are appropriate to use in different situations and consider the future directions of the field.
Study designs used in pharmacovigilance
Case reports and case series: Case reports are concerned with single patients who have been exposed to a drug and experienced an adverse reaction. Case series can refer to a collection of patients who have been exposed to the same drug and whose clinical outcomes are then evaluated and described. Alternatively, a case series can be a collection of patients with a single outcome, whose history is then checked to ascertain previous drug exposure.
Case-control studies: Case-control studies are retrospective studies where a group of patients with a particular disease (or ADR) are compared with a group of patients who do not have the disease, and their histories of previous exposure to a “risk factor” are compared. They can be used to study multiple drug exposures, uncommon diseases. They are relatively easy, fast and cheap in terms of data collection. However, case control studies also have their weaknesses i.e. Finding appropriate matched controls may be difficult.
Cohort studies: Cohort studies compare a group of individuals with a drug exposure to a group without the same exposure in terms of adverse outcomes. The study can be either prospective or retrospective. They allow calculation of incidence rates and precise risks and can be used to study multiple outcomes providing unbiased drug exposure data with selection bias less than in case-control studies. Their weaknesses are that they are relatively more expensive, especially the ad hoc studies.
Meta-analyses: In this era of evidence-based medicine, meta-analyses allow investigators to review clinical trial data systematically. Although most investigators are interested in the efficacy of treatments, it is also possible to investigate adverse outcomes systematically. A systematic review of randomized controlled trials involving administration of human albumin in critically ill patients has been undertaken.
Until recently, pharmacovigilance was mainly based on spontaneous reports, which provide low evidence of risks associated with medicines. Today, the importance of the full spectrum of the evidence hierarchy is recognized. This article reviews new approaches and data sources used in pharmacovigilance and shows that individual case safety reports, observational data, clinical trials and meta-analyses have unique characteristics that complement each other for the overall benefit–risk evaluation of medicines
In the past two decades, pharmacovigilance scientists have increasingly adopted the fundamentals of epidemiological research and applied them to the study of drugs. These techniques give us better understanding of the beneficial and adverse outcomes of medicines use. No doubt they will continue to play important roles in pharmacovigilance.