Use of leflunomide among girls and women of childbearing age and occurrence of leflunomide-exposed pregnancies in Germany.

Leflunomide is contraindicated during pregnancy and treatment cessation is recommended two years before pregnancy. We aimed to describe leflunomide use in women of childbearing age in Germany, the occurrence of pregnancies in women using leflunomide and malformations among children possibly exposed in utero. Using the GePaRD database (claims data, ∼20% of the German population), we determined annual age-standardized prevalences of leflunomide use between 2004 and 2019 among females aged 13-49 years. Further, we estimated the number of exposed pregnancies by assessing whether the exposure window assigned to the last dispensation before pregnancy (days covered by the dispensation plus two years) overlapped the onset of pregnancy or whether there was a dispensation in the first eight weeks of pregnancy. For exposed live births, a mother-baby linkage was performed and the presence of congenital malformation was assessed. The age-standardized prevalence of leflunomide use ranged between 0.34 and 0.46 per 1000 females during the study period. About one third of the users were ≤40 years. We identified 205 leflunomide-exposed pregnancies ending during the study period. 71% of these pregnancies ended in a live birth (26% preterm) and 10% in an induced abortion. In 86% of the live births (n=125) the mother-baby linkage was successful. Among these 125 children, 13 children (10%) had congenital malformations. In conclusion, we observed a considerable number of pregnancies in women using leflunomide in the two years before or during early pregnancy. This highlights the importance of monitoring the implementation of existing risk minimization measures for leflunomide in Germany.

Use of isotretinoin among girls and women of childbearing age and occurrence of isotretinoin-exposed pregnancies in Germany: A population-based study.

BACKGROUND: Exposure to isotretinoin during pregnancy must be avoided due to its teratogenicity, but real-world data on its use are scarce. We aimed to describe (i) isotretinoin use in women of childbearing age in Germany; (ii) the occurrence of isotretinoin-exposed pregnancies; and (iii) malformations among children exposed in utero. METHODS AND FINDINGS: Using observational data from the German Pharmacoepidemiological Research Database (GePaRD, claims data from approximately 20% of the German population), we conducted annual cross-sectional analyses to determine age-standardized prevalence of isotretinoin use between 2004 and 2019 among girls and women aged 13 to 49 years. In cohort analyses, we estimated the number of exposed pregnancies by assessing whether there was prescription supply overlapping the beginning of pregnancy (estimated supply was varied in sensitivity analyses) or a dispensation within the first 8 weeks of pregnancy. Data of live-born children classified as exposed in a critical period according to these criteria were reviewed to assess the presence of congenital malformations. The age-standardized prevalence of isotretinoin use per 1,000 girls and women increased from 1.20 (95% confidence interval [CI]: 1.16, 1.24) in 2004 to 1.96 (95% CI: 1.92, 2.01) in 2019. In the base case analysis, we identified 178 pregnancies exposed to isotretinoin, with the number per year doubling during the study period, and at least 45% of exposed pregnancies ended in an induced abortion. In sensitivity analyses, the number of exposed pregnancies ranged between 172 and 375. Among live-born children, 6 had major congenital malformations. The main limitation of this study was the lack of information on the prescribed dose, i.e., the supply had to be estimated based on the dispensed amount of isotretinoin. CONCLUSIONS: Isotretinoin use among girls and women of childbearing age increased in Germany between 2004 and 2019, and there was a considerable number of pregnancies likely exposed to isotretinoin in a critical period. This highlights the importance of monitoring compliance with the existing risk minimization measures for isotretinoin in Germany.

Use of Acitretin Among Girls and Women of Childbearing Age and Occurrence of Acitretin-Exposed Pregnancies in Germany.

BACKGROUND AND OBJECTIVE: Acitretin has long-lasting teratogenic properties. Therefore, pregnancies must be avoided during and within 3 years after acitretin treatment. We aimed to describe (i) acitretin use in women of childbearing age in Germany, (ii) the occurrence of acitretin-exposed pregnancies, and (iii) malformations among children exposed in utero. METHODS: Using 2004-2019 data from the German Pharmacoepidemiological Research Database (GePaRD-claims data from ~ 20% of the German population), we determined annual age-standardized prevalence of acitretin use among girls and women aged 13-49 years. In longitudinal analyses, we estimated the number of exposed pregnancies by assessing whether the exposure window assigned to the last dispensation before pregnancy (days covered by dispensation plus 3 years) overlapped the onset of pregnancy or whether there was a dispensation in the first eight weeks of pregnancy. Data of live-born children with in utero exposure to acitretin were reviewed to assess the presence of congenital malformations. RESULTS: The age-standardized prevalence of acitretin use per 1000 girls and women was 0.04 in 2019. We identified 35 acitretin-exposed pregnancies; 94.3% of these pregnancies were classified as exposed because they occurred within 3 years after stopping acitretin treatment. Among 18 live-born children linked to their mother, four children (22.2%) had congenital malformations (three children with a major malformation). CONCLUSIONS: We observed 35 acitretin-exposed pregnancies mainly because treatment ended too late before pregnancy. Approximately one in five children born from these pregnancies had malformations, highlighting the importance of drawing more attention to the long-lasting teratogenicity of this drug.

Risk Profiles of New Users of Oral Anticoagulants Between 2011 and 2019 in Germany.

Purpose: Over the last decade, the use of direct oral anticoagulants (DOACs) has strongly increased. We aimed to describe and compare risk profiles including potential changes over time among persons with non-valvular atrial fibrillation initiating treatment with different DOACs or phenprocoumon (vitamin K antagonist) between 2011 and 2019 in Germany. Patients and Methods: Using the German Pharmacoepidemiological Research Database (GePaRD; claims data of ~20% of the German population), we identified persons with a first dispensing of phenprocoumon or a DOAC and a diagnosis of non-valvular atrial fibrillation between August 2011 and December 2019. We described the morbidity of included patients prior to treatment initiation, stratified by year of treatment initiation. Results: Overall, we included 448,028 new users (phenprocoumon: N = 118,117, rivaroxaban: N = 130,997, apixaban: N = 130,300, edoxaban: N = 38,128, dabigatran: N = 30,486). Comparing new DOAC users in 2019, the proportion with prior ischemic stroke was highest for dabigatran (17%) and lowest for rivaroxaban (8%). The proportion with prior major bleeding was also highest for dabigatran (25%) and lowest for edoxaban (20%). New users of apixaban were oldest and, eg, showed the highest prevalence of congestive heart failure. Changes over time were most pronounced for phenprocoumon. For example, among persons initiating phenprocoumon in 2012 vs 2019, the proportion with prior major bleeding increased from 18% to 35%; the proportion with renal disease increased from 20% to 36% and the proportion with liver disease from 18% to 24%. Conclusion: This study demonstrated differences in risk profiles between new users of different oral anticoagulants and substantial changes over time among new phenprocoumon users. These differences have to be considered in head-to-head comparisons of these drugs based on observational data, especially regarding potential unmeasured confounding.

Prescribing of endothelin receptor antagonists and riociguat in women of childbearing age in a large German claims database study.

Use of endothelin receptor antagonists (ERAs) and riociguat, approved for treatment of pulmonary hypertension (PH), is contraindicated during pregnancy due to reported teratogenicity in animals. We aimed to investigate prescribing of these drugs in girls/women of childbearing age and to explore - as a secondary aim - the occurrence of pregnancies exposed to these drugs. Using the German Pharmacoepidemiological Research Database (GePaRD, claims data from 20% of the German population) we conducted cross-sectional analyses to determine prescribing prevalence of ERAs and riociguat between 2004 and 2019 and to characterize users and prescribing patterns. In a cohort analysis, we assessed the occurrence of pregnancies exposed to these drugs in the critical time window. Overall, we identified 407 women with ≥ 1 dispensation of bosentan between 2004 and 2019; the respective number was 73 for ambrisentan, 182 for macitentan, 31 for sitaxentan, and 63 for riociguat. In nearly all years, more than 50% of the girls/women were ≤ 40 years. Age-standardized prevalence was highest for bosentan (0.04/1000) in 2012 and 2013, followed by macitentan (0.03/1000) in 2018 and 2019. We observed 10 exposed pregnancies: 5 to bosentan, 3 to ambrisentan, and 2 to macitentan. The increased prevalence of macitentan and riociguat from 2014 onwards might reflect changes in PH treatment. Even though PH is a rare disease and pregnancy should be avoided in women with PH, particularly if they use ERAs, we identified pregnancies exposed to ERAs. Multi-database studies will be needed to assess the risk of these drugs on the unborn child.

Use of Methotrexate in Girls and Women of Childbearing Age, Occurrence of Methotrexate-Exposed Pregnancies and Their Outcomes in Germany: A Claims Data Analysis.

BACKGROUND AND OBJECTIVE: Methotrexate should be withdrawn before pregnancy because of its teratogenic potential. We aimed to describe the use of methotrexate in women of childbearing age in Germany and the occurrence and outcomes of pregnancies exposed to methotrexate. METHODS: Using the German Pharmacoepidemiological Research Database (GePaRD, covering ~ 20% of the German population), we determined the age-specific and age-standardized prevalence of methotrexate use for each year between 2004 and 2019 among women aged 13-49 years (cross-sectional analyses). In a cohort analysis, we assessed the number and outcomes of pregnancies exposed to methotrexate in the critical time window. Exposure was defined as a dispensation overlapping with the onset of pregnancy or a dispensation in the first 8 weeks of pregnancy. For children born from exposed pregnancies, the mother's and children's data were linked and the occurrence of malformations was assessed by reviewing all available data of these children. RESULTS: The age-standardized prevalence of methotrexate use per 1000 females increased from 1.5 in 2004 to 2.3 in 2019, i.e., by 52%. Overall, we identified 184 pregnancies exposed to methotrexate. Of these, 53% ended in a live birth (21% preterm) and 11% in an induced abortion. Among 81 live-born children linked to their mothers, five children (6%) had relevant malformations including congenital heart defects and musculoskeletal malformations. CONCLUSIONS: In Germany, the use of methotrexate in women of childbearing age has substantially increased since 2004. Despite the known teratogenic effect, there was a considerable number of exposed pregnancies.  Also, malformations likely associated with methotrexate and thus avoidable were observed.

Investigating drug safety in pregnancy based on the German Pharmacoepidemiological Research Database (GePaRD): A proof-of-concept analysis on the association between valproate and spina bifida.

PURPOSE: Large health-care databases are increasingly used for research on drug utilization and safety in pregnancy. For the German Pharmacoepidemiological Research Database (GePaRD), covering ~20% of the German population, algorithms have been developed to identify pregnancies, to estimate their date of onset and to link mothers to their babies. Using this methodology, we aimed to conduct a proof-of-concept analysis on the known association between valproate (VPA) exposure in early pregnancy and spina bifida in the exposed child. METHODS: We identified all pregnancies in GePaRD between 2006 and 2016 in women aged 12 to 50 years. To each VPA dispensation of these women, an exposure period was assigned, based on the dispensation date and the number of defined daily doses in the dispensed package. A pregnancy was classified as exposed to VPA in the critical time window if this exposure period overlapped with the first 55 days of pregnancy. Risk ratios were calculated for spina bifida in live births and induced abortions comparing VPA-exposed ones to all pregnancies. RESULTS: Overall, we identified 1 271 384 pregnancies fulfilling the inclusion criteria. Of these, 668 pregnancies (0.053%) were classified as exposed to VPA in the critical time window regarding spina bifida. An induced abortion accompanied by a diagnosis of spina bifida was observed in one of the VPA-exposed pregnancies (0.15%) and in 154 of all pregnancies (0.012%), yielding a risk ratio of 12.4 (95% confidence interval [CI]: 1.7-88.2). Out of 775 875 pregnancies ending in a live birth, 366 (0.047%) were classified as VPA exposed. A diagnosis of spina bifida was coded in 3 of 366 VPA-exposed live births (0.82%) and in 260 of all live births (0.03%), yielding a relative risk of 24.5 (95% CI: 7.9-76.0). CONCLUSIONS: Our proof-of-concept analysis based on GePaRD showed a strong association between intrauterine exposure to VPA and occurrence of spina bifida. The results are plausible and consistent with the literature, supporting the suitability of GePaRD and the developed algorithms to conduct studies on drug safety in pregnancy.

Effectiveness of Mammography Screening on Breast Cancer Mortality - A Study Protocol for Emulation of Target Trials Using German Health Claims Data.

Background: The efficacy of mammography screening in reducing breast cancer mortality has been demonstrated in randomized trials. However, treatment options - and hence prognosis - for advanced tumor stages as well as mammography techniques have considerably improved since completion of these trials. Consequently, the effectiveness of mammography screening under current conditions is unclear and controversial. The German mammography screening program (MSP), an organized population-based screening program, was gradually introduced between 2005 and 2008 and achieved nation-wide coverage in 2009. Objective: We describe in detail a study protocol for investigating the effectiveness of the German MSP in reducing breast cancer mortality in women aged 50 to 69 years based on health claims data. Specifically, the proposed study aims at estimating per-protocol effects of several screening strategies on cumulative breast cancer mortality. The first analysis will be conducted once 10-year follow-up data are available. Methods and Analysis: We will use claims data from five statutory health insurance providers in Germany, covering approximately 37.6 million individuals. To estimate the effectiveness of the MSP, hypothetical target trials will be emulated across time, an approach that has been demonstrated to minimize design-related biases. Specifically, the primary contrast will be in terms of the cumulative breast cancer mortality comparing the screening strategies of "never screen" versus "regular screening as intended by the MSP". Ethics and Dissemination: In Germany, the utilization of data from health insurances for scientific research is regulated by the Code of Social Law. All involved health insurance providers as well as the responsible authorities approved the use of the health claims data for this study. The Ethics Committee of the University of Bremen determined that studies based on claims data are exempt from institutional review. The findings of the proposed study will be published in peer-reviewed journals.

Fingolimod, teriflunomide and cladribine for the treatment of multiple sclerosis in women of childbearing age: description of drug utilization and exposed pregnancies in Germany.

BACKGROUND: Authorizations of fingolimod, teriflunomide and cladribine were accompanied by risk minimization measures concerning their teratogenic potential. Real-world data on their use are scarce. We aimed to assess trends in the use of fingolimod, teriflunomide and cladribine among women of childbearing age, estimate the number of pregnancies occurring under treatment and explore the occurrence of malformations in newborns exposed during early pregnancy in Germany. METHODS: Using the German Pharmacoepidemiological Research Database (GePaRD, claims data from ∼20% of the German population), we determined annual age-standardized prevalences of fingolimod, teriflunomide and cladribine use from their authorization until 2019 among women aged 13-49 years (cross-sectional analyses). In longitudinal analyses, we estimated the number of exposed pregnancies by assessing whether there was an overlap between the exposure windows assigned to dispensations and the onset of pregnancy or a dispensation in the first eight weeks of pregnancy. For live births, a mother-baby linkage was performed. All available data of children with in-utero exposure and malformation codes in the first year of life were reviewed to verify the occurrence of congenital malformations. RESULTS: For fingolimod, the age-standardized prevalence of use per 1,000 females increased from 0.14 in 2011 to 0.46 in 2019; for teriflunomide, from 0.06 in 2013 to 0.28 in 2019; for cladribine, from 0.01 in 2017 to 0.07 in 2019. The proportion of users aged ≤40 years was 60% for fingolimod, 45% for teriflunomide and 65% for cladribine. We identified 136 pregnancies exposed to fingolimod, 50 to teriflunomide and one to cladribine. For fingolimod and teriflunomide, respectively, 72% and 62% of exposed pregnancies ended in a live birth. Mother-newborn linkage was successful in 64 (fingolimod) and 20 (teriflunomide) live-born children. Among these, there were six with relevant malformations (mainly heart defects) for fingolimod and two for teriflunomide. CONCLUSION: Use of fingolimod, teriflunomide and cladribine among women of childbearing age has substantially increased in Germany. A high proportion of users was in age groups in which pregnancies typically occur. Despite risk minimization measures, early pregnancy exposure to these drugs was observed.

Record linkage of claims and cancer registries data-Evaluation of a deterministic linkage approach based on indirect personal identifiers.

PURPOSE: In Germany, record linkage of claims and cancer registry data is cost- and time-consuming, since up until recently no unique personal identifier was available in both data sources. The aim of this study was to evaluate the feasibility and performance of a deterministic linkage procedure based on indirect personal identifiers included in the data sources. METHODS: We identified users of glucose-lowering drugs with residence in four federal states in Northern and Southern Germany (Bavaria, Bremen, Hamburg, Lower Saxony) in the German Pharmacoepidemiological Research Database (GePaRD) and assessed colorectal and thyroid cancer cases. Cancer registries of the federal states selected all colorectal and thyroid cancer cases between 2004 and 2015. A deterministic linkage approach was performed based on indirect personal identifiers such as year of birth, sex, area of residence, type of cancer and an absolute difference between the dates of cancer diagnosis in both data sources of at most 90 days. Results were compared to a probabilistic linkage using "direct" personal identifiers (gold standard). RESULTS: The deterministic linkage procedure yielded a sensitivity of 71.8% for colorectal cancer and 66.6% for thyroid cancer. For thyroid cancer, the sensitivity improved when using only inpatient diagnosis to define cancer in GePaRD (71.4%). Specificity was always above 99%. Using the probabilistic linkage to define cancer cases, the risk for colorectal cancer was estimated 10 percentage points lower than when using the deterministic approach. CONCLUSIONS: Sensitivity of the deterministic linkage approach appears to be too low to be considered as reasonable alternative to the probabilistic linkage procedure.

Regional Variations in Outpatient Antibiotic Prescribing in Germany: A Small Area Analysis Based on Claims Data.

A comprehensive small area description of regional variations in outpatient antibiotic prescribing in Germany is lacking. Using the German Pharmacoepidemiological Research Database (GePaRD), a claims database covering ~20% of the German population, we determined the age- and sex-standardized prescription rates of antibiotics (number of outpatient prescriptions per 1000 persons/year). We calculated these prescription rates overall and on the level of 401 German districts for the calendar years 2010 and 2018. In 2018, the standardized prescription rate of antibiotics in the total study population was 23% lower than in 2010 (442 vs. 575 per 1000 persons/year). Among 0-17-year-olds, prescription rates across districts ranged from 312 to 1205 in 2010 and from 188 to 710 in 2018 per 1000 persons/year; among adults (≥18 years), they ranged from 388 to 841 in 2010 and from 300 to 693 in 2018 per 1000 persons/year. Despite the overall decline in outpatient antibiotic prescribing between 2010 and 2018, regional variations at the district level remained high in all age groups in Germany. Identifying reasons that explain the persistently high prescription rates in certain regions will be helpful in designing effective and tailored measures to further improve antibiotic stewardship in these regions.

Screening colonoscopy similarly prevented distal and proximal colorectal cancer: a prospective study among 55-69-year-olds.

OBJECTIVES: We aimed to evaluate the effectiveness of screening colonoscopy in reducing incidence of distal vs. proximal colorectal cancer (CRC) in persons aged 55-69 years. STUDY DESIGN AND SETTING: Using observational data from a German claims database (German Pharmacoepidemiological Research Database), we emulated a target trial with two arms: Colonoscopy screening vs. no-screening at baseline. Adjusted cumulative incidence of total, distal, and proximal CRC over 11 years of follow-up was estimated in 55-69-year-olds at an average CRC risk and without colonoscopy, polypectomy, or fecal occult blood test before baseline. RESULTS: Overall, 307,158 persons were included (screening arm: 198,389 and control arm: 117,399). The adjusted 11-year risk of any CRC was 1.62% in the screening group and 2.38% in the no-screening group resulting in a relative risk of 0.68 (95% CI: 0.63-0.73). The relative risk was 0.67 for distal CRC (95% CI: 0.62-0.73) and 0.70 (95% CI: 0.63-0.79) for proximal CRC. The cumulative incidence curves of the groups crossed after 6.7 (distal CRC) and 5.0 years (proximal CRC). CONCLUSION: Our results suggest that colonoscopy is effective in preventing distal and proximal CRC. Unlike previous studies not using a target trial approach, we found no relevant difference in the effectiveness by location.

[Linkage of claims data with data from epidemiological cancer registries: possibilities and limitations in the German federal states]. / Verknüpfung von Abrechnungsdaten gesetzlicher Krankenkassen mit Daten epidemiologischer Krebsregister: länderspezifische Möglichkeiten und Limitationen.

BACKGROUND: In recent years, there has been an increasing demand for the reuse of research data in accordance with the so-called FAIR principles. This would allow researchers to conduct projects on a broader data basis and to investigate new research questions by linking different data sources. OBJECTIVES: We explored if nationwide linking of claims data from statutory health insurances (SHI) with data from population-based cancer registries can be used to obtain additional information on cancer that is missing in claims data and to assess the validity of SHI tumour diagnoses. This paper focuses on describing the specific requirements of German federal states for such data linkage. MATERIALS AND METHODS: The Pharmacoepidemiological Research Database GePaRD at the Leibniz Institute for Prevention Research and Epidemiology - BIPS and six cancer registries were used as data sources. The logistically complex direct linkage was compared with a less complex indirect linkage. For this purpose, permission had to be obtained for GePaRD and for each cancer registry from the respective responsible authority. RESULTS: Regarding the linkage of cancer registry data with GePaRD, the cancer registries showed profound differences in the modalities for data provision, ranging from a complete rejection to an uncomplicated implementation of linkage procedures. DISCUSSION: In Germany, a consistent legal framework is needed to adequately enable the reuse and record linkage of personal health data for research purposes according to the FAIR principles. The new law on the consolidation of cancer registry data could provide a remedy regarding the linkage of cancer registry data with other data sources.

Dispensation Patterns of Glucose-Lowering Drugs in Newly Diagnosed Type 2 Diabetes: Routine Data Analysis of Insurance Claims in Germany.

AIMS: To describe dispensation patterns of glucose-lowering drugs in newly diagnosed type 2 diabetes in Germany. MATERIALS AND METHODS: Based on claims data from four statutory health insurances (German Pharmacoepidemiological Research Database,>25 million insurants), all individuals with newly diagnosed type 2 diabetes were identified. Eligible patients had a first diagnosis for type 2 diabetes between January 2012 and December 2016. We analyzed the dispensation patterns of first-line glucose-lowering therapies initiated in the year after diabetes diagnosis and patterns of second-line therapies dispensed one year after first-line treatment. RESULTS: A total of 356,647 individuals with newly diagnosed type 2 diabetes were included (average age [SD]: 63.5 [13.4] years; 49.3% males). Of the 31.6% of individuals who were pharmacologically treated in the year after diagnosis, metformin monotherapy was most frequently dispensed (73.1%), followed by dual therapy of metformin and dipeptidyl peptidase-4 inhibitors (DPP-4is) (6.4%), and monotherapy with DPP-4is (2.9%). From 2012 through 2016, sulfonylurea dispensations were reduced by more than 50%. Dispensations for combination therapies with DPP-4is increased up to 10.6%. Glucagon-like peptide-1 receptor agonists and sodium-glucose co-transporter-2 inhibitors contributed to 2% of all treatments. After a median of 5 months, 20.0% of individuals on pharmacological therapy initiated second-line glucose-lowering treatment. CONCLUSIONS: Data from German statutory health insurances (2012 to 2016) showed that most individuals with newly diagnosed type 2 diabetes were dispensed metformin monotherapy in line with diabetes care guidelines. A substantial decrease in the use of sulfonylureas was observed after the introduction of DPP-4i and GLP-1 receptor agonists.

Avoiding Time-Related Biases: A Feasibility Study on Antidiabetic Drugs and Pancreatic Cancer Applying the Parametric g-Formula to a Large German Healthcare Database.

PURPOSE: Investigating intended or unintended effects of sustained drug use is of high clinical relevance but remains methodologically challenging. This feasibility study aims to evaluate the usefulness of the parametric g-formula within a target trial for application to an extensive healthcare database in order to address various sources of time-related biases and time-dependent confounding. PATIENTS AND METHODS: Based on the German Pharmacoepidemiological Research Database (GePaRD), we estimated the pancreatic cancer incidence comparing two hypothetical treatment strategies for type 2 diabetes mellitus (T2DM), i.e., (A) sustained metformin monotherapy vs (B) combination therapy with DPP-4 inhibitors after one year metformin monotherapy. We included 77,330 persons with T2DM who started metformin therapy at baseline between 2005 and 2011. Key aspects for avoiding time-related biases and time-dependent confounding were the emulation of a target trial over a 7-year follow-up period and application of the parametric g-formula. RESULTS: Over the 7-year follow-up period, 652 out of the 77,330 study subjects had a diagnosis of pancreatic cancer. Assuming no unobserved confounding, we found evidence that the metformin/DPP-4i combination therapy increased the risk of pancreatic cancer compared to a sustained metformin monotherapy (risk ratio: 1.47; 95% bootstrap CI: 1.07-1.94). The risk ratio decreased in sensitivity analyses addressing protopathic bias. CONCLUSION: While protopathic bias could not fully be ruled out, and computational challenges necessitated compromises in the analysis, the g-formula and target trial emulation proved useful: Self-inflicted biases were avoided, observed time-varying confounding was adjusted for, and the estimated risks have a clear causal interpretation.

[Secondary Data for Pharmacoepidemiological Research - Making the Best of It!] / Nutzung von Sekundärdaten für die pharmakoepidemiologische Forschung ­ machen wir das Beste draus!

Studies using secondary data such as health care claims data are often faced with methodological challenges due to the time-dependence of key quantities or unmeasured confounding. In the present paper, we discuss approaches to avoid or suitably address various sources of potential bias. In particular, we illustrate the target trial principle, marginal structural models, and instrumental variables with examples from the "GePaRD" database. Finally, we discuss the strengths and limitations of record linkage which can sometimes be used to supply missing information.

Persistence and adherence to non-vitamin K antagonist oral anticoagulant treatment in patients with atrial fibrillation across five Western European countries.

AIMS: To assess persistence and adherence to non-vitamin K antagonist oral anticoagulant (NOAC) treatment in patients with atrial fibrillation (AF) in five Western European healthcare settings. METHODS AND RESULTS: We conducted a multi-country observational cohort study, including 559 445 AF patients initiating NOAC therapy from Stockholm (Sweden), Denmark, Scotland, Norway, and Germany between 2011 and 2018. Patients were followed from their first prescription until they switched to a vitamin K antagonist, emigrated, died, or the end of follow-up. We measured persistence and adherence over time and defined adequate adherence as medication possession rate ≥90% among persistent patients only. RESULTS: Overall, persistence declined to 82% after 1 year and to 63% after 5 years. When including restarters of NOAC treatment, 85% of the patients were treated with NOACs after 5 years. The proportion of patients with adequate adherence remained above 80% throughout follow-up. Persistence and adherence were similar between countries and was higher in patients starting treatment in later years. Both first year persistence and adherence were lower with dabigatran (persistence: 77%, adherence: 65%) compared with apixaban (86% and 75%) and rivaroxaban (83% and 75%) and were statistically lower after adjusting for patient characteristics. Adherence and persistence with dabigatran remained lower throughout follow-up. CONCLUSION: Persistence and adherence were high among NOAC users in five Western European healthcare settings and increased in later years. Dabigatran use was associated with slightly lower persistence and adherence compared with apixaban and rivaroxaban.

Use of intravenous iron and risk of anaphylaxis: A multinational observational post-authorisation safety study in Europe.

PURPOSE: This post-authorisation safety study estimated the risk of anaphylaxis in patients receiving intravenous (IV) iron in Europe, with interest in iron dextran and iron non-dextrans. Studies conducted in the United States have reported risk of anaphylaxis to IV iron ranging from 2.0 to 6.8 per 10 000 first treatments. METHODS: Cohort study of IV iron new users, captured mostly through pharmacy ambulatory dispensing, from populations covered by health and administrative data sources in five European countries from 1999 to 2017. Anaphylaxis events were identified through an algorithm that used parenteral penicillin as a positive control. RESULTS: A total of 304 210 patients with a first IV iron treatment (6367 iron dextran), among whom 13-16 anaphylaxis cases were identified and reported as a range to comply with data protection regulations. The pooled unadjusted incidence proportion (IP) ranged from 0.4 (95% confidence interval [CI], 0.2-0.9) to 0.5 (95% CI, 0.3-1.0) per 10 000 first treatments. No events were identified at first dextran treatments. There were 231 294 first penicillin treatments with 30 potential cases of anaphylaxis (IP = 1.2; 95% CI, 0.8-1.7 per 10 000 treatments). CONCLUSION: We found an IP of anaphylaxis from 0.4 to 0.5 per 10 000 first IV iron treatments. The study captured only a fraction of IV iron treatments administered in hospitals, where most first treatments are likely to happen. Due to this limitation, the study could not exclude a differential risk of anaphylaxis between iron dextran and iron non-dextrans. The IP of anaphylaxis in users of penicillin was consistent with incidences reported in the literature.

First-Time Users of ADHD Medication Among Children and Adolescents in Germany: An Evaluation of Adherence to Prescribing Guidelines Based on Claims Data.

Background: Drug utilization studies based on real-world data are vital for the identification of potentially needed improvements to rational prescribing. This is particularly important for the pharmacological treatment of children and adolescents with attention-deficit hyperactivity disorder (ADHD) due to the associated potential side effects and the frequent use. Whereas prevalent use is well-characterized, studies on first-time use of ADHD medication are scarce. This study aimed to evaluate off-label prescribing in first-time users of ADHD medication among children and adolescents in Germany based on three criteria: (i) lack of a documented ADHD diagnosis; (ii) first-time pharmacological treatment with a second-line drug; and (iii) patient age below 6 years. Methods: Based on German claims data, we included children and adolescents aged 0-17 years with a first-time dispensation of any ADHD medication in the period 2015-2017. These first-time users were characterized with regard to sex, age, specialty of the prescribing physician, documentation of an ADHD diagnosis, psychiatric hospitalization, psychiatric comorbidities, and history of other psychopharmacological drugs at first-time use. Results: The study population comprised 18,703 pediatric first-time users of ADHD medication. Of these, 9.8% had no documented ADHD diagnosis. Most of the ADHD drug users received first-line ADHD pharmacotherapy (methylphenidate, atomoxetine), whereas 2.6% were prescribed second-line ADHD medication (lisdexamfetamine, guanfacine, dexamfetamine, multiple ADHD drugs) as first drug. Overall, 1.2% of first-time users were aged below 6 years. A total of 12.7% of the study population met any off-label criterion. Conclusions: About 13% of pediatric first-time users of ADHD medication in Germany received an off-label pharmacotherapy at first-time use. Prescribing ADHD medication without a confirmed ADHD diagnosis was the most common of the three assessed off-label criteria. Off-label prescribing regarding drug choice and age of patients only occurred in a small percentage of initial pharmacological ADHD treatment. Our results suggest the need for improvement in rational prescribing, especially with regard to diagnostic requirements.

Good Practice Data Linkage (GPD): A Translation of the German Version.

The data linkage of different data sources for research purposes is being increasingly used in recent years. However, generally accepted methodological guidance is missing. The aim of this article is to provide methodological guidelines and recommendations for research projects that have been consented to across different German research societies. Another aim is to endow readers with a checklist for the critical appraisal of research proposals and articles. This Good Practice Data Linkage (GPD) was already published in German in 2019, but the aspects mentioned can easily be transferred to an international context, especially for other European Union (EU) member states. Therefore, it is now also published in English. Since 2016, an expert panel of members of different German scientific societies have worked together and developed seven guidelines with a total of 27 practical recommendations. These recommendations include (1) the research objectives, research questions, data sources, and resources; (2) the data infrastructure and data flow; (3) data protection; (4) ethics; (5) the key variables and linkage methods; (6) data validation/quality assurance; and (7) the long-term use of data for questions still to be determined. The authors provide a rationale for each recommendation. Future revisions will include new developments in science and updates of data privacy regulations.