Pharmacoepidemiology – current opportunities and challenges

  • Jesper Hallas




Pharmacoepidemiology is defined as the the study of the use and the effects of drugs in large groups of

people. It can be viewed as an epidemiological discipline with particular focus on drugs. The Scandinavians

pioneered the developement of methods to study drug utilization. The ATC and DDD methodology is now a

widely accepted consensus on how to categorise drugs and compare sales of drugs of different potency. The

hierachy of available designs to study drug effects is described. There is an inverse relationship between the

validity of a study design and its resource requirements. One of the most pervasive methodological problems

of pharmacoepidemiology is the possibility of confounding by indication. Often, such confounding can only

be handled by mounting a randomised trial. If a trial is unethical or unfeasible, the research question has the

potential of becoming af standing controversy. The emergence of large population based prescription databases

is an exciting new development in pharmacoepidemiology. The validity of drug exposure data is discussed.

It is established that data from a pharmacy based database should be preferred over data from a GP

based database. Whether interview data are preferable to dispensing data can not be established in general

but may occasionally be inferred from the context of the research question.

How to Cite
Hallas, J. (2009). Pharmacoepidemiology – current opportunities and challenges. Norsk Epidemiologi, 11(1).