Norwegian Journal of Epidemiology 2001; 11 (1): 3-4 3

Notes from the guest editors:

Pharmacoepidemiology – a bridge science

In 1962, the former chief medical officer in Norway,Dr. Karl Evang (1901-1981), claimed that "The intro-duction of modern pharmacological drugs representsthe greatest progress ever made in the history ofmankind". Because of the "drug revolution" during thedecades since World War II, physicians have now theopportunity to treat patients more safely, rapidly andeffectively than ever before. Drug therapy plays animportant role in protecting, maintaining and restoringthe health of people.

However, medications may be a double-edgedsword. The benefits of modern drug therapy arereduced by inappropriate prescribing practice, poly-pharmacy, and adverse drug reactions. Unnecessaryprescriptions shift the focus from non-pharmacologicaltreatment, and contribute to a medicalisation of bothlife stress and an increasing number of risk factors.The rapidly increasing costs of modern drug therapyrepresent a growing concern for third party payers, e.g.the national insurance service.

While clinical pharmacology in general relates toeffects of drugs in the human body, epidemiologicalmethods must be used for investigating patterns andeffects of drugs in defined populations. Drug epidemi-ology, or pharmacoepidemiology, is simply the appli-cation of epidemiological methods to pharmacologicalissues. However, the term "epidemiology" implies thatpharmacoepidemiologic studies are population-based,and may link health events to drug use. In their text-book, Porta and Hartzema define pharmacoepidemio-logy as the “application of epidemiologic reasoning,methods, and knowledge to the study of the uses andeffects of drugs in human population”.

Pharmacoepidemiology has been described as abridge science because it spans both clinical pharma-cology, drug utilization, and epidemiology. Theinvolvement of the multiple disciplines is reflected bythe different professions involved in the research, e.g.physicians, pharmacists, statisticians and medicalsociologists.

In practice, pharmacoepidemiologic research canbe divided into two main fields. The first includes stu-dies of variation in drug use in populations, drug usepatterns, identification of predictors for use, generationof hypotheses exploring variations, and public healthimpacts of drug use. The other field includes follow-upstudies of e.g., side-effects, adverse drug effects, – and

post marketing studies investigating long-term effectsof specific drugs in a population setting. These latterstudies are needed to complete what we know aboutdrug effects documented in clinical trials. In Norway, drug utilization research dates back tothe early 1970s under the WHO Drug UtilizationResearch Group, now renamed EuroDURG. TheNorwegian "Pharmacoepidemiology Forum” is theNorwegian research group within the EuroDURG.This Forum is a network of researchers throughout thecountry and who share a common interest in pharma-coepidemiology.

During the 1st Nordic Conference in Epidemiology(Bergen, June 2000), Pharmacoepidemiology Forumwas responsible for setting up a satellite symposiumabout Pharmacoepidemiology in the Nordic countries.We are thankful to the Norwegian Ministry of SocialWelfare and Health for their economic support to thissymposium. Because the National Board of Healthpreviously has proposed that a national drug prescrip-tion registry should be established in Norway, focus onthis symposium was largely limited to research basedon health registers and prescription databases. The pre-sentations from this symposium have now been elabo-rated to the manuscripts presented in the symposiumsection in this Journal.

One particular feature with the Nordic countriesand which is important for epidemiology is the natio-nal high quality health registries. The first nationaldisease registry in the world was The NorwegianLeprosy Registry which was established back in 1856.Later, separate individual-based registries for e.g.,tuberculosis, cancer, births, epidemic infectious disea-ses, and vaccinations have been established for theNorwegian population.

In the Norwegian Ministry of Social Welfare andHealth, plans for a new registry, a National Drug Pre-scription Registry, are currently being elaborated. Themanuscripts presented in the symposium section of theJournal represent a significant contribution from thescientific community to this work. Both the objectives,contents, and organization of this probable futurestatistics are addressed. The international experiencesreported here are quite uniform when it comes to oneessential issue: a unique person identifying numbermust be included in the database of a future prescrip-tion registry. This is because a person identifying code

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is the prerequisite for doing longitudinal studies aswell as record linkage with data from national orregional health surveys or with other national healthregistries. Several of the contributing authors of thisissue give examples which illustrate some of the bene-fits which can be obtained for health care and researchby linking prescription data with endpoints of drugtreatment (e.g., morbidity and mortality data, bloodpressure and serum lipid levels). The lack of a popula-tion based prescription statistics is probably an impor-tant explanation for the relatively low scientific outputof pharmacoepidemiologic research in Norway today.A national drug prescription registry may become auseful tool for research and quality assurance to thebenefits of the population. However, it may also end

up as a “data graveyard”. The difference between thetwo will to a large extent depend on which data areincluded, and how the database will be organized andfunded.

To get a "taste" of some of the pharmacoepidemio-logic research activities presently going on in Norway,researchers have been invited to submit original papersto this theme issue. There are great variations in bothmethods, materials and objectives in the seven originalcontributions presented here. All articles have beenpeer reviewed. Bon appétit!

The guest editors want to thank all authors for their contribu-tions. Thank you also to our external referees, and to chiefeditor Trond Peder Flaten for an excellent collaborationduring this work.

Anne Elise Eggen, MSc Pharm, MPH, PhD

Associate professor at the Department of Pharmacoepide-miology and pharmacy practice, Institute of Pharmacy,University of Tromsø

Jørund Straand, MD, PhD

Clinical specialty in general practice. Associate professorat the Department of General Practice/Family Medicine,Institute of General Practice and Community medicine,University of Oslo.