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Background: The purpose was to describe utilization of selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs), including trends in prevalence, characteristics of users, drug switching and changes in prescribed doses in a large group of pregnant women across four Nordic countries., Methods: A drug utilization study based on linked individual-level data from the nationwide prescription- and medical birth registers in Denmark, Iceland, Norway and Sweden. The study population comprised all pregnancies in these countries, resulting in a live birth or stillbirth after gestational week 22 from January 1st 2008 to December 31st 2012 (N = 1 162 470). In addition to the main study drugs SSRIs and SNRIs, we included (concurrent) use of other antidepressants, antipsychotics, anxiolytics and hypnotics., Results: A total of 38 219 (3.3%) pregnancies were exposed to SSRIs and 5 634 (0.5%) to SNRIs. Prevalence of SSRI and SNRI use varied by country (1.8% in Norway to 7.0% in Iceland). Use and prescribed dosages decreased with each passing trimester of pregnancy; prevalence was 2.7% at conception, and 2.1%, 1.7% and 1.3% respectively in 1st, 2nd and 3rd trimester. In 0.6% of pregnancies women filled a prescription before pregnancy and in every trimester. In one third of exposed pregnancies, women were also dispensed anxiolytics, hypnotics or sedatives., Conclusion: Use of SSRI and SNRI use during pregnancy varied between the Nordic countries, but the overall prevalence remained low and relatively stable from 2008 to 2012. The low prevalence of use and high proportion of women who discontinue treatment in pregnancy raise questions about adequate treatment of depression in pregnant women.

Purpose: All five Nordic countries have nationwide prescription databases covering all dispensed drugs, with potential for linkage to outcomes. The aim of this review is to present an overview of therapeutic areas studied and methods applied in pharmacoepidemiologic studies using data from these databases., Methods: The study consists of a Medline-based structured literature review of scientific papers published during 2005-2010 using data from the prescription databases in Denmark, Finland, Iceland, Norway, and Sweden, covering 25 million inhabitants. Relevant studies were analyzed in terms of pharmacological group, study population, outcomes examined, type of study (drug utilization vs. effect of drug therapy), country of origin, and extent of cross-national collaboration., Results: A total of 515 studies were identified. Of these, 262 were conducted in Denmark, 97 in Finland, 4 in Iceland, 87 in Norway, and 61 in Sweden. Four studies used data from more than one Nordic country. The most commonly studied drugs were those acting on the nervous system, followed by cardiovascular drugs and gastrointestinal/endocrine drugs. A total of 228 studies examined drug utilization and 263 focused on the effects and safety of drug therapy. Pregnant women were the most commonly studied population in safety studies, whereas prescribers' adherence to guidelines was the most frequent topic of drug utilization studies., Conclusions: The Nordic prescription databases, with their possibility of record-linkage, represent an outstanding resource for assessing the beneficial and adverse effects of drug use in large populations, under routine care conditions, and with the potential for long-term follow-up., (Copyright © 2013 John Wiley & Sons, Ltd.)

Objective: To assess whether maternal use of selective serotonin reuptake inhibitors (SSRIs) increases the risk of persistent pulmonary hypertension in the newborn, and whether such an effect might differ between specific SSRIs., Design: Population based cohort study using data from the national health registers., Setting: Denmark, Finland, Iceland, Norway, and Sweden, 1996-2007., Participants: More than 1.6 million infants born after gestational week 33., Main Outcome Measures: Risks of persistent pulmonary hypertension of the newborn associated with early and late exposure to SSRIs during pregnancy and adjusted for important maternal and pregnancy characteristics. Comparisons were made between infants exposed and not exposed to SSRIs., Results: Around 30 000 women had used SSRIs during pregnancy and 11 014 had been dispensed an SSRI later than gestational week 20. Exposure to SSRIs in late pregnancy was associated with an increased risk of persistent pulmonary hypertension in the newborn: 33 of 11 014 exposed infants (absolute risk 3 per 1000 liveborn infants compared with the background incidence of 1.2 per 1000); adjusted odds ratio 2.1 (95% confidence interval 1.5 to 3.0). The increased risks of persistent pulmonary hypertension in the newborn for each of the specific SSRIs (sertraline, citalopram, paroxetine, and fluoxetine) were of similar magnitude. Filling a prescription with SSRIs before gestational week 8 yielded slightly increased risks: adjusted odds ratio 1.4 (95% confidence interval 1.0 to 2.0)., Conclusions: The risk of persistent pulmonary hypertension of the newborn is low, but use of SSRIs in late pregnancy increases that risk more than twofold. The increased risk seems to be a class effect.

Objective: To compare national use of attention-deficit/hyperactivity disorder (ADHD) drugs between five Nordic countries., Method: A population-based drug utilisation study based on nationwide prescription databases, covering in total 24 919 145 individuals in 2007. ADHD drugs defined according to the World Health Organization Anatomic Therapeutic Chemical classification system as centrally acting sympathomimetics (N06BA)., Results: The 2007 prevalence of ADHD drug use among the total Nordic population was 2.76 per 1000 inhabitants, varying from 1.23 per 1000 in Finland to 12.46 per 1000 in Iceland. Adjusting for age, Icelanders were nearly five times more likely than Swedes to have used ADHD drugs (Prev.Ratio = 4.53, 95% CI: 4.38-4.69). Prevalence among boys (age 7-15) was fourfold the prevalence among girls (Prev.Ratio = 4.28, 95% CI: 3.70-4.96). The gender ratio was diminished among adults (age 21 +) (Prev.Ratio = 1.24, CI: 1.21-1.27)., Conclusion: A considerable national variation in use of ADHD drugs exists between the Nordic countries., (© 2010 John Wiley & Sons A/S.)

The Nordic countries have a long tradition of registry-based epidemiological research. Many population-based health registries were established in the 1960s, with use of unique personal identifiers facilitating linkage between registries. In recent years, each country has established a national database to track prescription drugs dispensed to individuals in ambulatory care. The objectives were to present an overview of the prescription databases established in the Nordic countries, as well as to elaborate on their unique potential for record linkage and cross-national comparison of drug utilization. Five Nordic countries collect drug exposure data based on drugs dispensed at pharmacies and have the potential to link these data to health outcomes. The databases together cover 25 million inhabitants (Denmark: 5.5 million; Finland: 5.3 million; Iceland: 0.3 million; Norway: 4.8 million; and Sweden: 9.2 million). In 2007, the registries encompassed 17 million prescription drug users (68% of the total population). We provide examples of how these databases have been used for descriptive drug utilization studies and analytical pharmacoepidemiological studies linking drug exposure to other health registries. Comparisons are facilitated by many similarities among the databases, including data source, content, coverage and methods used for drug utilization studies and record linkage. There are, however, some differences in coding systems and validity, as well as in some access and technical issues. To perform cross-national pharmacoepidemiological studies, resources, networks and time are needed, as well as methods for pooling data. Interpretation of results needs to account for inter-country heterogeneity and the possibility of spurious relationships. The Nordic countries have a unique potential for collaborative high-quality cross-national pharmacoepidemiological studies with large populations. This research may assist in resolving safety issues of international interest, thus minimizing the risk of either over-reacting on possible signals or underestimating drug safety issues.