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Types of studies

Drug utilization studies describe the use of a given treatment or class of treatments in the underlying population, including distribution of age and sex, comorbidities, prescriber specialty, typical treatment duration, treatment interruptions, indications (including off-label use), prevalence of use by persons with potential contraindications, and changes of use over time. An extension of a drug utilization study is a risk minimization study, in which an impact of a risk minimization measure (e.g., a warning added to a label) may be studied by conducting a before-and-after comparison, to determine whether and how prescribing patterns change in response to the measure.

Postauthorisation safety studies (PASS) are often required by regulators as a condition for approval of newly marketed treatments, with the aim to refine evidence about side effects that are rare, develop over a long period of time, or may be more relevant in special patient populations, such as the elderly or pregnant women. Safety assessment for drug use in pregnancy is one of the most important missions of post-market pharmacoepidemiology because pre-approval trials typically exclude pregnant women, while safe treatments are crucial for healthy pregnancy among women with chronic diseases such as diabetes, depression, epilepsy, or autoimmune diseases.

Comparative effectiveness studies compare head-to-head real-world effectiveness of two or more different established treatments for the same indication. Similarly to PASS, comparative effectiveness studies can assess clinically relevant questions in special patient subgroups, and routinely collected health data are helpful in assembling subgroups of meaningful sizes to allow conclusive results.

Clinical course of disease studies are relevant to pharmacoepidemiology even if they do not address a specific treatment. Such studies are frequently conducted in anticipation of a product’s approval to estimate the background risks of expected adverse events in the indicated patient population. Once the new medicine becomes available, absence of an associated increase in the background risk of an adverse event following increasing uptake of the new medicine is reassuring evidence of favorable benefit-risk balance. Conversely, an increase in a suspected risk coinciding with the uptake of the new medication may be an important safety signal to be investigated in a formal pharmacoepidemiologic study.

Prognostic biomarker studies use data on molecular and genetic biomarkers to identify potential subgroups of patients that may derive a greater or a lesser benefit from a given medicine. In addition to informing current treatment decisions, such studies provide information for drug development studies, as prognostic biomarkers may be used to validate pathways for developing future medications.