The First Decade with the Swedish Prescribed Drug Register – A Systematic Review of the Output in the Scientific Literature

Abstract

The aim of this study was to quantify and characterize the scientific output from the Swedish Prescribed Drug Register (SPDR) the first decade after its establishment. A systematic literature search was performed in Medline, EMBASE and PubMed (2005-2014). Additional publications were identified by personal knowledge, reference lists, contact with active authors and a citation search in Web of Sciences. Publications using SPDR data were included in the analysis and characterized regarding study type, presence of patient-level record linkage, target population and topic. A total of 719 publications were identified in the literature search and an additional 148 by other strategies. Three hundred and thirty-eight studies fulfilled the inclusion criteria. The majority were analytic (n = 166; 49.1%) or descriptive (n = 100; 29.5%). The remaining studies focused on validation (n = 20; 5.9%), health economics (n = 16; 4.7%) or miscellaneous (n = 36; 10.7%). The analytic studies investigating effects of drug exposure focused mainly on safety (n = 46) and/or effectiveness (n = 24). The first publications appeared in 2007 (n = 6), and in 2014, 90 articles using SPDR were published. Over the years, linkage with other registers using the personal identity number increased (0-88.9% of the publications). The population was often selected by age (49.7%), condition (45.0%) and/or drug (22.8%) and concerned predominantly psychiatric (29.0%) and cardiovascular (20.4%) diseases. In conclusion, this study illustrates that the establishment of a nationwide individual-based register on dispensed prescription drugs facilitates an encouraging development of pharmacoepidemiological research, both regarding the number of publications and the scientific level of the analyses.Increased availability of register data on drug treatment has contributed to the rapid developments within pharmacoepidemiology [1][2][3]. In the Nordic prescription databases, established 1993 to 2006, detailed and comprehensive nationwide information on dispensed drugs, patient and prescriber is available [4]. In Sweden, the Swedish Prescribed Drug Register (SPDR) was expanded to include the identity of the patient on 1 July 2005 [5]. Thus, since then and for research purposes after ethics application [6], the unique personal identity number given to all Swedish citizens has allowed linkage between drug dispensing data and other registers [7].The Swedish Prescribed Drug Register now contains one decade of patient-level data on all dispensed prescription drugs in Sweden. The first 10 calender years of SPDR include purchases of 891 million prescriptions and 44,829 million defined daily doses [8]. Each year, drug purchases by more than 6 million inhabitants are registered in SPDR [8], representing about two-thirds of the Swedish population.As the establishment of an individual-based register on dispensed prescription drugs can be questioned on the basis of integrity issues, it is important to balance these risks with potential benefits, for example the contri...

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