Kari Furu

The Nordic countries as a cohort for pharmacoepidemiological research.

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.

Selective serotonin reuptake inhibitors during pregnancy and risk of persistent pulmonary hypertension in the newborn: population based cohort study from the five Nordic countries

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.

Risk of Fetal Death after Pandemic Influenza Virus Infection or Vaccination

BACKGROUND During the 2009 influenza A (H1N1) pandemic, pregnant women were at risk for severe influenza illness. This concern was complicated by questions about vaccine safety in pregnant women that were raised by anecdotal reports of fetal deaths after vaccination. METHODS We explored the safety of influenza vaccination of pregnant women by linking Norwegian national registries and medical consultation data to determine influenza diagnosis, vaccination status, birth outcomes, and background information for pregnant women before, during, and after the pandemic. We used Cox regression models to estimate hazard ratios for fetal death, with the gestational day as the time metric and vaccination and pandemic exposure as time-dependent exposure variables. RESULTS There were 117,347 eligible pregnancies in Norway from 2009 through 2010. Fetal mortality was 4.9 deaths per 1000 births. During the pandemic, 54% of pregnant women in their second or third trimester were vaccinated. Vaccination during pregnancy substantially reduced the risk of an influenza diagnosis (adjusted hazard ratio, 0.30; 95% confidence interval [CI], 0.25 to 0.34). Among pregnant women with a clinical diagnosis of influenza, the risk of fetal death was increased (adjusted hazard ratio, 1.91; 95% CI, 1.07 to 3.41). The risk of fetal death was reduced with vaccination during pregnancy, although this reduction was not significant (adjusted hazard ratio, 0.88; 95% CI, 0.66 to 1.17). CONCLUSIONS Pandemic influenza virus infection in pregnancy was associated with an increased risk of fetal death. Vaccination during pregnancy reduced the risk of an influenza diagnosis. Vaccination itself was not associated with increased fetal mortality and may have reduced the risk of influenza-related fetal death during the pandemic. (Funded by the Norwegian Institute of Public Health.).

Prescription drug use among fathers and mothers before and during pregnancy. A population‐based cohort study of 106 000 pregnancies in Norway 2004–2006

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT Mothers are using medicines during pregnancies; the extent varies across the world and is generally difficult to compare. In this registry-based study, we examined more than 100,000 Norwegian pregnancies and described the drug prescription pattern of both fathers and mothers around conception and during pregnancy (mothers). WHAT THIS STUDY ADDS In every trimester of pregnancy, about 30% of the mothers was dispensed a drug. The total drug exposure did not seem to diminish throughout pregnancy. One-quarter of the fathers was dispensed drugs during the last 3 months prior to conception. AIMS The primary aim of this study was to describe the use of prescribed drugs in both mothers and fathers before and during pregnancy in Norway. METHODS This population-based cohort study was based on data retrieved from the Medical Birth Registry of Norway and the Norwegian Prescription Database. These registries cover the entire population of Norway. Information on >100,000 births during 2004-2006 in the birth registry was linked to prescription data. Prescriptions issued to mothers just prior to, during and after the pregnancies as well as prescriptions to fathers just prior to conception were identified. RESULTS Among mothers, 83% were prescribed drugs during the period 3 months prior to estimated conception until 3 months after giving birth. The mothers who received drugs were prescribed on average 3.3 different Anatomical Therapeutic Chemical (ATC) codes (range 1-38). During pregnancy, 57% were prescribed drugs. In the first trimester, 33% of mothers were dispensed drugs, while the figure was 29% for mothers in the last trimester. Among fathers, 25% used prescribed drugs during the 3 months prior to conception, with on average 1.9 different ATC codes (range 1-22). CONCLUSION Large proportions of both fathers and mothers were dispensed drugs prior to conception or during pregnancy. While there is a high awareness of the issues involved in maternal drug use in pregnancy, possible teratogenic effects of drug use in fathers shortly before conception should be further explored.

Use of ADHD drugs in the Nordic countries: a population-based comparison study.

Zoëga H, Furu K, Halldórsson M, Thomsen PH, Sourander A, Martikainen JE. Use of ADHD drugs in the Nordic countries: a population‐based comparison study.

Selective serotonin reuptake inhibitors and venlafaxine in early pregnancy and risk of birth defects: population based cohort study and sibling design.

Objective To assess whether use of specific selective serotonin reuptake inhibitors (SSRIs) or venlafaxine in early pregnancy is associated with an increased risk of birth defects, with emphasis on cardiovascular birth defects even when accounting for lifestyle or other familial confounding. Design Multicountry population based cohort study, including sibling controlled design. Setting Nordic population (Denmark, Finland, Iceland, Norway, and Sweden) identified from nationwide health registers at different periods in 1996-2010. Population The full study cohort included women giving birth to 2.3 million live singletons. The sibling cohort included 2288 singleton live births. The sibling controlled analyses included sibling pairs who were discordant for exposure to SSRIs or venlafaxine and birth defects. Main outcome measure Prevalence of birth defects, including subtypes of cardiac defects. Odds ratio of birth defects from logistic and conditional logistic regression. Results Among 36 772 infants exposed to any SSRI in early pregnancy, 3.7% (n=1357) had a birth defect compared with 3.1% of 2 266 875 unexposed infants, yielding a covariate adjusted odds ratio of 1.13 (95% confidence interval 1.06 to 1.20). In the sibling controlled analysis the adjusted odds ratio decreased to 1.06 (0.91 to 1.24). The odds ratios for any cardiac birth defect with use of any SSRI or venlafaxine were 1.15 (95% confidence interval 1.05 to 1.26) in the covariate adjusted analysis and 0.92 (0.72 to 1.17) in the sibling controlled analysis. For atrial and ventricular septal defects the covariate adjusted odds ratio was 1.17 (1.05 to 1.31). Exposure to any SSRI or venlafaxine increased the prevalence of right ventricular outflow tract obstruction defects, with a covariate adjusted odds ratio of 1.48 (1.15 to 1.89). In the sibling controlled analysis the adjusted odds ratio decreased to 0.56 (0.21 to 1.49) for any exposure to SSRIs or venlafaxine and right ventricular outflow tract obstruction defects. Conclusions In this large Nordic study no substantial increase was found in prevalence of overall cardiac birth defects among infants exposed to SSRIs or venlafaxine in utero. Although the prevalence of septal defects and right ventricular outflow tract defects was higher in exposed infants, the lack of an association in the sibling controlled analyses points against a teratogenic effect of these drugs.

The Nordic prescription databases as a resource for pharmacoepidemiological research—a literature review

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.

Undertreatment and overtreatment with statins: the Oslo Health Study 2000-2001.

Objective.  We examined the prevalence and factors associated with use of cholesterol‐lowering statins in the population.

Selective Serotonin Reuptake Inhibitors During Pregnancy and Risk of Stillbirth and Infant Mortality

IMPORTANCE Maternal psychiatric disease is associated with adverse pregnancy outcomes. Use of selective serotonin reuptake inhibitors (SSRIs) during pregnancy has been associated with congenital anomalies, neonatal withdrawal syndrome, and persistent pulmonary hypertension of the newborn. However, the risk of stillbirth and infant mortality when accounting for previous maternal psychiatric disease remains unknown. OBJECTIVE To study risk of stillbirth and infant mortality associated with use of SSRIs during pregnancy. DESIGN, SETTING, AND PARTICIPANTS Population-based cohort study from all Nordic countries (Denmark, Finland, Iceland, Norway, and Sweden) at different periods from 1996 through 2007. The study included women with singleton births. We obtained information on maternal use of SSRIs from prescription registries. Maternal characteristics, pregnancy, and neonatal outcomes were obtained from patient and medical birth registries. MAIN OUTCOME MEASURES We used logistic regression to estimate relative risks of stillbirth, neonatal death, and postneonatal death associated with SSRI use during pregnancy taking into account maternal characteristics and previous psychiatric hospitalization. RESULTS Among 1,633,877 singleton births in the study, 6054 were stillbirths; 3609, neonatal deaths; and 1578, postneonatal deaths. A total of 29,228 (1.79%) of mothers had filled a prescription for an SSRI during pregnancy. Women exposed to an SSRI presented with higher rates of stillbirth (4.62 vs 3.69 per 1000, P = .01) and postneonatal death (1.38 vs 0.96 per 1000, P = .03) than those who did not. The rate of neonatal death was similar between groups (2.54 vs 2.21 per 1000, P = .24). Yet in multivariable models, SSRI use was not associated with stillbirth (adjusted odds ratio [OR], 1.17; 95% CI, 0.96-1.41; P = .12), neonatal death (adjusted OR, 1.23; 95% CI, 0.96-1.57; P = .11), or postneonatal death (adjusted OR, 1.34; 95% CI, 0.97-1.86; P = .08). Estimates were further attenuated when stratified by previous hospitalization for psychiatric disease. The adjusted OR for stillbirth in women with a previous hospitalization for psychiatric disease was 0.92 (95% CI, 0.66-1.28; P = .62) and was 1.07 (95% CI, 0.84-1.36; P = .59) for those who had not been previously hospitalized. The corresponding ORs for neonatal death were 0.89 (95% CI, 0.58-1.39; P = .62) for women who were hospitalized and 1.14 (95% CI, 0.84-1.56; P = .39) for women who were not. For postneonatal death, the ORs were 1.02 (95% CI, 0.61-1.69; P = .95) for women who were hospitalized and 1.10 (95% CI, 0.71-1.72; P = .66) for women who were not. CONCLUSIONS AND RELEVANCE Among women with singleton births in Nordic countries, no significant association was found between use of SSRIs during pregnancy and risk of stillbirth, neonatal mortality, or postneonatal mortality. However, decisions about use of SSRIs during pregnancy must take into account other perinatal outcomes and the risks associated with maternal mental illness.

Pharmacologically inappropriate prescriptions for elderly patients in general practice: How common? Baseline data from The Prescription Peer Academic Detailing (Rx-PAD) study

Objective. To assess Norwegian general practitioners’ (GPs’) level of potentially harmful drug prescribing for elderly patients. Design. Prescription data for 12 months were retrospectively retrieved from the Norwegian Prescription Database (NorPD). Data were assessed in relation to 13 prescription quality indicators. Setting. General practice. Subjects. A total of 454 GPs attending continuous medical education (CME) groups in Southern Norway, 85 836 patients ≥70 years who received any prescription from the GPs during the study period. Main outcome measures. Number of prescriptions assessed in relation to pharmacological inappropriateness based on a list of 13 explicit prescription quality indicators. Results. Some 18.4% of the patients (66% females with mean age 79.8 years, 34% males with mean age 78.7 years) received one or more inappropriate prescriptions from their GP. An NSAID in a potentially harmful combination with another drug (7%) and a long-acting benzodiazepine (4.6%) were the most frequent inappropriate prescriptions made. Doctor characteristics associated with more inappropriate prescribing practice were old age and working single-handed with many elderly patients. Conclusion. The study reveals areas where GPs’ prescribing practice for elderly patients can be improved and which can be targeted in educational interventions.