Pharmacoepidemiology – from description to quality assessment. A Swedish perspective

Abstract

ABSTRACT

Parallel with increasing concerns about drug safety, the importance of drug surveillance and the application

of epidemiological techniques have grown rapidly during the past decades. The increasing use of computerized

health care data facilitates the establishment of populations large enough to allow epidemiological

studies. By the use of computerized pharmacy or billing records, drug exposure is linked to files which

include outcome data (diagnoses). Pioneering pharmacoepidemiology surveys of prescriptions purchased

from defined populations were initiated in the late 1960s. Two such population-based drug databases for

research (Jämtland and Tierp) are still in use in Sweden and can provide key epidemiological data such as

incidence

and prevalence of drug use by age and sex. This basic information on drug use can only be

obtained if there is a personal identifier on the prescription. Important studies such as quality of care, polypharmacy,

drug interactions, drug abuse and physicians' prescribing habits all require data on drug use by

individuals. Unfortunately, because of sensitivity to the issue of data confidentiality in Sweden, the correspondingly

recorded data on prescriptions relative to individual patients is not available for use in health

care audits or research. With these limitations in access to patient specific data on drug use, focus is now

instead on improving the quality of drug prescribing by use of available drug statistics. The number of

drugs that account for 90% of the use – the Drug Utilization 90% segment – and adherence to guidelines in

this segment are now being tested as general indicators for assessing the quality of drug prescribing.