The mother and unborn child may be particularly vulnerable to side effects or adverse reactions from medication with potentially tragic outcomes. Yet while clinical trials generally cannot provide data on medicinal side effects during pregnancy such knowledge is hugely important, particularly with the rising trend in the west to delay child bearing to ages where chronic
conditions
requiring treatment are likely to be more common. Prescription data for pregnant women becomes a useful tool for allowing researchers to determine whether
the
unborn child has been exposed to the medication, which may influence assessments of drug safety. Equally important is information that a given drug is safe to give to a pregnant woman, because untreated diseases in the mother can be harmful for the baby. Linkage of data on births, prescriptions, and hospital diagnoses enables these types of studies. Analysis of prescription data is also
important for monitoring the response to new drug regulations. As an example, Dr Ehrenstein describes a study commissioned by the European Medicines Agency on the anti-diabetic drug rosiglitazone. The drug had been approved in 2000 for
treating patients who did not respond adequately to
prescriptions for rosiglitazone issued during its entire life on the market,” explains Dr Ehrenstein. “Also, which is quite unique for Nordic databases, in Denmark, we have data on results of laboratory tests, so we could see objective evidence of diabetes control before and after patients discontinued rosiglitazone.” Dr Ehrenstein and her colleagues collaborated on the study with colleagues at the Boston
Collaborative
Drug Surveillance Program, who provided data from the United Kingdom’s General Practice
Research
Database. “It was exciting to see that results from the two databases were quite consistent with each other despite different mechanisms collection.”
of data Yet while the information available from
prescription databases tends to be more useful than that obtained from patients, challenges remain. In particular it is difficult to ascertain how promptly or faithfully a prescription has been followed. “For example, we know the exact date of sale of a given prescription, but we cannot be sure that a patient took the medication on that day,” explains Dr Ehrenstein. Repeat prescriptions give some idea of the use of treatments for chronic conditions. However,
Vera Ehrenstein Born in 1971 in Moscow. BS in biology (University of Illinois, USA); Master of Public Health (2000) and Doctor of Science (2008), both from Boston University School of Public health. Currently associate professor at the Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark.
Contact: Tel: +45 871 56351 Email:
ve@dce.au.dk Web: www.
kea.au.dk
Project Information AT A GLANCE
Project Title: Pharmacoepidemiology and pharmacovigilance: monitoring safety of medications
Project Objective: To provide real-life data on benefits of harms of medications in human populations
Project Duration and Timing: Ongoing
Project Funding: Pharmaceutical companies, regulators, private and government foundation
Project Partners: Universities, government agencies, industry
Main Contact:
“Denmark not only has universal healthcare but thorough records exist of each individual’s contact with the health care system”
typical treatments. However, several studies linked the drug to higher risks of heart attack and the decision was made to suspend it. Dr Ehrenstein and her colleagues a
conducted study to assess factors
associated with changes in rosiglitazone use as a result of the evidence of the side effects, and whether patients who were taken off the drug following its suspension had been able to keep their diabetes under control. “It was possible for us to conduct this study since we had data on
www.projectsmagazine.eu.com for medication prescribed for use “as
needed”, details of the actual use remains unknown. Difficulties also arise in disentangling side effects of treatments from symptoms that result from the disease itself. “This is a pervasive problem of observational studies of drug effects and it is known as confounding by indication,” says Dr Ehrenstein. Despite
the difficulties, the non-
experimental approach to epidemiological research has drawn some useful conclusions that seem very reliable, as emphasised in
the consistency between results on rosiglitazone from Dr Ehrenstein’s data and that of the Boston Collaborative Drug Surveillance Program. Dr Ehrenstein and her colleagues are currently engaged in a number of ongoing multinational long- term pharmacovigilance studies on new drug classes. She concludes, “As long as new drugs enter the market there will always be a need for assessment of their real-life performance, a task, for which Danish registries offer unique advantages.”
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