Safety profile of rivaroxaban in first-time users treated for venous thromboembolism in four European countries.

BACKGROUND: The European rivaroxaban post-authorization safety study evaluated bleeding risk among patients initiated on rivaroxaban or vitamin K antagonists for the treatment and secondary prevention of venous thromboembolism in routine clinical practice. METHODS: Cohorts were created using electronic healthcare databases from the UK, the Netherlands, Germany and Sweden. Patients with a first prescription of rivaroxaban or vitamin K antagonist during the period from December 2011 (in the UK, January 2012) to December 2017 (in Germany, December 2016) for venous thromboembolism indication, with no record of atrial fibrillation or recent cancer history, were observed until the occurrence of each safety outcome (hospitalization for intracranial, gastrointestinal, urogenital or other bleeding), death or study end (December 2018; in Germany, December 2017). Crude incidence rates of each outcome per 100 person-years were computed. RESULTS: Overall, 44 737 rivaroxaban and 45 842 vitamin K antagonist patients were enrolled, mean age, 59.9-63.8 years. Incidence rates were similar between rivaroxaban and vitamin K antagonist users with some exceptions, including higher incidence rates for gastrointestinal bleeding in rivaroxaban users than in vitamin K antagonist users. Among rivaroxaban users, mortality and bleeding risk generally increased with age, renal impairment and diabetes. CONCLUSIONS: This study provides further data from routine clinical practice that broadly support safety profile of rivaroxaban for VTE indication and complement findings from previous randomized clinical trials.

Challenges and lessons learned from a long-term postauthorisation safety study programme of rivaroxaban in Europe.

OBJECTIVES: To describe opportunities and challenges experienced from the four pharmacoepidemiological database studies included in the rivaroxaban post authorisation safety study (PASS) programme and propose ways to maximise the value of population-based observational research when addressing regulatory requirements. DESIGN: PASS programme of rivaroxaban carried out as part of the regulatory postapproval commitment to the European Medicines Agency. SETTING: Clinical practice in Germany, the Netherlands, Sweden and the UK (electronic health records)-undertaken by pharmacoepidemiology research teams using country-specific databases with different coding structures. PARTICIPANTS: 355 152 patients prescribed rivaroxaban and 338 199 patients prescribed vitamin K antagonists. RESULTS: Two major challenges that were encountered throughout the lengthy PASS programme were related to: (1) finalising country-tailored study designs before the extent of rivaroxaban uptake was known, and (2) new research questions that arose during the programme (eg, those relating to an evolving prescribing landscape). RECOMMENDATIONS: We advocate the following strategies to help address these major challenges (should they arise in any future PASS): conducting studies based on a common data model that enable the same analytical tools to be applied when using different databases; maintaining early, clear, continuous communication with the regulator (including discussing the potential benefit of studying drug use as a precursor to planning a safety study); consideration of adaptive designs whenever uncertainty exists and following an initial period of data collection; and setting milestones for the review of study objectives.

Evaluation of Physician Knowledge of Safety and Safe Use Information for Intravitreal Aflibercept Injection in Europe: A Second Survey of Physicians Following Dissemination of Updated Risk-Minimization Materials.

BACKGROUND: Materials have been distributed in the European Union to inform physicians on the safe use of intravitreal aflibercept (IVT-AFL) as part of the risk-minimization plan for IVT-AFL. OBJECTIVE: We aimed to measure physician knowledge and understanding of key safety information for IVT-AFL. METHODS: The current study was a follow-up cross-sectional survey ('wave 2') to an earlier survey ('wave 1') examining the effectiveness of the IVT-AFL educational materials by assessing physician knowledge of the key safety information. Based on wave 1 results, the educational materials were revised to focus more on items of key concern (e.g., use in women of childbearing potential, procedural information); physicians in France, Germany, Italy, Spain, and the UK completed a questionnaire to evaluate their knowledge of key safety information in the revised educational materials. RESULTS: Among 454 physician respondents (of 4715 invited; response rate 9.6%), most reported having received the IVT-AFL Summary of Product Characteristics (SmPC; 89%) and Prescriber Guide (82%). More than half reported receiving the Injection Procedure Video (54%) and Patient Booklet (65%). The highest percentage of correct answers was observed for questions concerning procedural steps, the most important risks, and safe use as emphasized by the educational materials and the SmPC. CONCLUSION: Physician knowledge and understanding of safe use of IVT-AFL, including for questions that prompted revisions to the educational materials, suggests the need to reconsider methods for developing educational materials to follow best practices (e.g., focusing on only key messages and pretesting with end users).

Sex differences in the generalizability of randomized clinical trials in heart failure with reduced ejection fraction.

AIMS: In order to understand how sex differences impact the generalizability of randomized clinical trials (RCTs) in patients with heart failure (HF) and reduced ejection fraction (HFrEF), we sought to compare clinical characteristics and clinical outcomes between RCTs and HF observational registries stratified by sex. METHODS AND RESULTS: Data from two HF registries and five HFrEF RCTs were used to create three subpopulations: one RCT population (n = 16 917; 21.7% females), registry patients eligible for RCT inclusion (n = 26 104; 31.8% females), and registry patients ineligible for RCT inclusion (n = 20 810; 30.2% females). Clinical endpoints included all-cause mortality, cardiovascular mortality, and first HF hospitalization at 1 year. Males and females were equally eligible for trial enrolment (56.9% of females and 55.1% of males in the registries). One-year mortality rates were 5.6%, 14.0%, and 28.6% for females and 6.9%, 10.7%, and 24.6% for males in the RCT, RCT-eligible, and RCT-ineligible groups, respectively. After adjusting for 11 HF prognostic variables, RCT females showed higher survival compared to RCT-eligible females (standardized mortality ratio [SMR] 0.72; 95% confidence interval [CI] 0.62-0.83), while RCT males showed higher adjusted mortality rates compared to RCT-eligible males (SMR 1.16; 95% CI 1.09-1.24). Similar results were also found for cardiovascular mortality (SMR 0.89; 95% CI 0.76-1.03 for females, SMR 1.43; 95% CI 1.33-1.53 for males). CONCLUSION: Generalizability of HFrEF RCTs differed substantially between the sexes, with females having lower trial participation and female trial participants having lower mortality rates compared to similar females in the registries, while males had higher than expected cardiovascular mortality rates in RCTs compared to similar males in registries.

Time Trends in Patient Characteristics of New Rivaroxaban Users with Atrial Fibrillation in Germany and the Netherlands.

BACKGROUND: Use of the direct oral anticoagulant rivaroxaban has strongly increased in Europe since its market approval for non-valvular atrial fibrillation in 2011. Patients characteristics of rivaroxaban initiators may have changed over time but this has not been investigated so far. OBJECTIVE: We aimed to describe time trends of patient baseline characteristics among new rivaroxaban users with non-valvular atrial fibrillation from 2011 to 2016/17 in two European countries. METHODS: We used data from Germany (German Pharmacoepidemiological Research Database) and the Netherlands (PHARMO Database Network). We included new rivaroxaban users with (i) a first dispensing between 2011 and 2016/17, (ii) ≥ 2 years of age, and (iii) a diagnosis of non-valvular atrial fibrillation and described their baseline medication and comorbidity prior to starting rivaroxaban stratified by year of inclusion. RESULTS: Overall, 130,652 new rivaroxaban users were included during the study period (Germany: N = 127,743, the Netherlands: N = 2909). The sex ratio and median age remained relatively stable over time. The proportion of patients without prior use of oral anticoagulants before initiation of rivaroxaban increased in both countries between 2011 and 2016/17 (Germany: from 51 to 76%, the Netherlands: from 57 to 85%). In Germany, we observed a relative decrease by 27% in the proportion of new rivaroxaban users with a history of ischemic stroke and by 18% in the proportion with a transient ischemic attack at baseline. No such a pattern was observed in the Netherlands. The proportion of patients with heart failure at baseline showed a three-fold increase in the Netherlands, while there was a relative decrease by 12% in Germany. CONCLUSIONS: Patient characteristics of new rivaroxaban users with non-valvular atrial fibrillation changed between 2011 and 2016/17, but changes differed between countries. These patterns have methodological implications. They have to be considered in the interpretation of observational studies comparing effectiveness and safety of oral anticoagulants, especially regarding potential bias due to unmeasured confounding.

Safety and effectiveness of rivaroxaban for prevention of stroke in patients with nonvalvular atrial fibrillation: analysis of routine clinical data from four countries.

BACKGROUND: The safety and effectiveness of rivaroxaban versus vitamin K antagonists (standard of care [SOC]) for stroke prevention in patients with nonvalvular atrial fibrillation (NVAF) was evaluated in Europe. RESEARCH DESIGN AND METHODS: Observational studies were conducted in the UK, the Netherlands, Germany, and Sweden. Primary safety outcomes were hospitalization for intracranial hemorrhage, gastrointestinal bleeding, or urogenital bleeding among new users of rivaroxaban and SOC with NVAF; outcomes were analyzed using cohort (rivaroxaban or SOC use) and nested case-control designs (current vs nonuse). Statistical analyses comparing rivaroxaban and SOC cohorts were not performed. RESULTS: Overall, 162,919 rivaroxaban users and 177,758 SOC users were identified. In the cohort analysis, incidence ranges for rivaroxaban users were 0.25-0.63 events per 100 person-years for intracranial bleeding, 0.49-1.72 for gastrointestinal bleeding, and 0.27-0.54 for urogenital bleeding. Corresponding ranges for SOC users were 0.30-0.80, 0.30-1.42, and 0.24-0.42, respectively. In the nested case-control analysis, current SOC use generally presented a greater risk of bleeding outcomes than nonuse. Rivaroxaban use (vs nonuse) was associated with a higher risk of gastrointestinal bleeding, but a similar risk of intracranial or urogenital bleeding, in most countries. Ischemic stroke incidence ranged from 0.31 to 1.52 events per 100 person-years for rivaroxaban users. CONCLUSIONS: Incidences of intracranial bleeding were generally lower with rivaroxaban than with SOC, whereas incidences of gastrointestinal and urogenital bleeding were generally higher. The safety profile of rivaroxaban for NVAF in routine practice is consistent with findings from randomized controlled trials and other studies.

Smartphone detection of atrial fibrillation using photoplethysmography: a systematic review and meta-analysis.

OBJECTIVES: Timely diagnosis of atrial fibrillation (AF) is essential to reduce complications from this increasingly common condition. We sought to assess the diagnostic accuracy of smartphone camera photoplethysmography (PPG) compared with conventional electrocardiogram (ECG) for AF detection. METHODS: This is a systematic review of MEDLINE, EMBASE and Cochrane (1980-December 2020), including any study or abstract, where smartphone PPG was compared with a reference ECG (1, 3 or 12-lead). Random effects meta-analysis was performed to pool sensitivity/specificity and identify publication bias, with study quality assessed using the QUADAS-2 (Quality Assessment of Diagnostic Accuracy Studies-2) risk of bias tool. RESULTS: 28 studies were included (10 full-text publications and 18 abstracts), providing 31 comparisons of smartphone PPG versus ECG for AF detection. 11 404 participants were included (2950 in AF), with most studies being small and based in secondary care. Sensitivity and specificity for AF detection were high, ranging from 81% to 100%, and from 85% to 100%, respectively. 20 comparisons from 17 studies were meta-analysed, including 6891 participants (2299 with AF); the pooled sensitivity was 94% (95% CI 92% to 95%) and specificity 97% (96%-98%), with substantial heterogeneity (p<0.01). Studies were of poor quality overall and none met all the QUADAS-2 criteria, with particular issues regarding selection bias and the potential for publication bias. CONCLUSION: PPG provides a non-invasive, patient-led screening tool for AF. However, current evidence is limited to small, biased, low-quality studies with unrealistically high sensitivity and specificity. Further studies are needed, preferably independent from manufacturers, in order to advise clinicians on the true value of PPG technology for AF detection.

Identification and Mapping Real-World Data Sources for Heart Failure, Acute Coronary Syndrome, and Atrial Fibrillation.

BACKGROUND: Transparent and robust real-world evidence sources are increasingly important for global health, including cardiovascular (CV) diseases. We aimed to identify global real-world data (RWD) sources for heart failure (HF), acute coronary syndrome (ACS), and atrial fibrillation (AF). METHODS: We conducted a systematic review of publications with RWD pertaining to HF, ACS, and AF (2010-2018), generating a list of unique data sources. Metadata were extracted based on the source type (e.g., electronic health records, genomics, and clinical data), study design, population size, clinical characteristics, follow-up duration, outcomes, and assessment of data availability for future studies and linkage. RESULTS: Overall, 11,889 publications were retrieved for HF, 10,729 for ACS, and 6,262 for AF. From these, 322 (HF), 287 (ACS), and 220 (AF) data sources were selected for detailed review. The majority of data sources had near complete data on demographic variables (HF: 94%, ACS: 99%, and AF: 100%) and considerable data on comorbidities (HF: 77%, ACS: 93%, and AF: 97%). The least reported data categories were drug codes (HF, ACS, and AF: 10%) and caregiver involvement (HF: 6%, ACS: 1%, and AF: 1%). Only a minority of data sources provided information on access to data for other researchers (11%) or whether data could be linked to other data sources to maximize clinical impact (20%). The list and metadata for the RWD sources are publicly available at www.escardio.org/bigdata. CONCLUSIONS: This review has created a comprehensive resource of CV data sources, providing new avenues to improve future real-world research and to achieve better patient outcomes.

Evaluating patient and physician knowledge of risks and safe use of rivaroxaban: a survey across four countries.

BACKGROUND: At the request of the European Medicines Agency, a Prescriber Guide and Patient Alert Card were developed to increase awareness and understanding about the initiation of rivaroxaban and potential bleeding risk associated with its use. This study evaluated physician and patient awareness and understanding of key safety messages in these educational materials in three waves. RESEARCH DESIGN AND METHODS: Three cross-sectional surveys were administered to physicians and one survey was administered to patients (wave 1 only) with recent rivaroxaban experience in France, Germany, Spain, and the United Kingdom. RESULTS: Patient and physician knowledge of key safety information in the educational materials was generally high. Patients' knowledge was high for questions related to bleeding risk (80% responded correctly), indication (96%), consulting their doctor (86%-91%), and informing other physicians they are taking rivaroxaban (95%). Physicians' knowledge was particularly high for questions related to bleeding risk (92%-94% across waves), populations at increased risk of serious side effects (76%-94%), contraindications (70%-92%), and invasive procedures (76%-82%). CONCLUSIONS: Among patients and physicians, the highest levels of knowledge were on the most important risks, as expected. The Prescriber Guide and Patient Alert Card were found to be useful sources of information.

Generalizability of randomized controlled trials in heart failure with reduced ejection fraction.

BACKGROUND: Heart failure (HF) trials have stringent inclusion and exclusion criteria, but limited data exist regarding generalizability of trials. We compared patient characteristics and outcomes between patients with HF and reduced ejection fraction (HFrEF) in trials and observational registries. METHODS AND RESULTS: Individual patient data for 16 922 patients from five randomized clinical trials and 46 914 patients from two HF registries were included. The registry patients were categorized into trial-eligible and non-eligible groups using the most commonly used inclusion and exclusion criteria. A total of 26 104 (56%) registry patients fulfilled the eligibility criteria. Unadjusted all-cause mortality rates at 1 year were lowest in the trial population (7%), followed by trial-eligible patients (12%) and trial-non-eligible registry patients (26%). After adjustment for age and sex, all-cause mortality rates were similar between trial participants and trial-eligible registry patients [standardized mortality ratio (SMR) 0.97; 95% confidence interval (CI) 0.92-1.03] but cardiovascular mortality was higher in trial participants (SMR 1.19; 1.12-1.27). After full case-mix adjustment, the SMR for cardiovascular mortality remained higher in the trials at 1.28 (1.20-1.37) compared to RCT-eligible registry patients. CONCLUSION: In contemporary HF registries, over half of HFrEF patients would have been eligible for trial enrolment. Crude clinical event rates were lower in the trials, but, after adjustment for case-mix, trial participants had similar rates of survival as registries. Despite this, they had about 30% higher cardiovascular mortality rates. Age and sex were the main drivers of differences in clinical outcomes between HF trials and observational HF registries.

Serological response to nifurtimox in adult patients with chronic Chagas disease: An observational comparative study in Argentina.

Nifurtimox is indicated in Chagas disease but determining its effectiveness in chronic disease is hindered by the length of time needed to demonstrate negative serological conversion. We manually reviewed long-term follow-up data from hospital records of patients with chronic Chagas disease (N = 1,497) in Argentina diagnosed during 1967-1980. All patients were aged ≥18 years at diagnosis and were either treated with nifurtimox (n = 968) or received no antitrypanosomal treatment (n = 529). The primary endpoint was negative seroconversion (the "event"), defined as a change from positive to negative in the serological or parasitological laboratory test used at diagnosis. Time to event was from baseline visit to date of endpoint event or censoring. The effectiveness of nifurtimox versus no treatment was estimated with Cox proportional hazard regression using propensity scores with overlap weights to calculate the hazard ratio and 95% confidence interval. The nifurtimox group was younger than the untreated group (mean, 32.4 vs. 40.3 years), with proportionally fewer females (47.9% vs. 60.1%), and proportionally more of the nifurtimox group than the untreated group had clinical signs and symptoms of Chagas disease at diagnosis (28.9% vs. 14.0%). Median maximum daily dose of nifurtimox was 8.0 mg/kg/day (interquartile range [IQR]: 8.0-9.0) and median treatment duration was 44 days (IQR: 1-90). Median time to event was 2.1 years (IQR: 1.0-4.5) for nifurtimox-treated and 2.4 years (IQR: 1.0-4.2) for untreated patients. Accounting for potential confounders, the estimated hazard ratio (95% confidence interval) for negative seroconversion was 2.22 (1.61-3.07) favoring nifurtimox. Variable treatment regimens and follow-up duration, and an uncommonly high rate of spontaneous negative seroconversion, complicate interpretation of this epidemiological study, but with the longest follow-up and largest cohort analyzed to date it lends weight to the benefit of nifurtimox in adults with chronic Chagas disease. Trial registration: The study protocol was registered at ClinicalTrials.gov: NCT03784391.

Prevalence of adverse pregnancy outcomes after exposure to interferon beta prior to or during pregnancy in women with MS: Stratification by maternal and newborn characteristics in a register-based cohort study in Finland and Sweden.

BACKGROUND: Previous studies reported no increase in the prevalence of adverse pregnancy outcomes after exposure to interferon-beta (IFN-beta). However, no study has investigated if the prevalence of these outcomes after IFN-beta exposure is modified by maternal and newborn characteristics. Our objective was to describe the stratified prevalence of adverse pregnancy outcomes among women with multiple sclerosis (MS) exposed only to IFN-beta or unexposed to any MS disease modifying drugs (MSDMDs). METHODS: This population-based cohort study using Finnish (1996-2014) and Swedish (2005-2014) register data included pregnancies of women with MS exposed only to IFN-beta 6 months before or during pregnancy (n=718) or unexposed to MSDMDs (n=1397). The outcome prevalences were described stratified by maternal and newborn characteristics, with 95% confidence intervals (CIs). Confounder-adjusted analyses were performed if the prevalence results indicated modified effect of IFN-beta in specific strata. RESULTS: The stratified analysis indicated that the prevalence of serious (anomaly or stillbirth) and other adverse pregnancy outcomes was similar among the exposed and unexposed, with no statistically significant difference. Among women treated for MS >5 years, serious adverse pregnancy outcomes occurred in 4.3% (95%CI: 1.9-8.3%) of pregnancies exposed only to IFN-beta 6 months before or during pregnancy and in 2.7% (95%CI: 1.2-5.0%) of unexposed pregnancies. The confounder adjusted analyses did not support the hypothesis that MS treatment duration before pregnancy would modify the risk of adverse pregnancy outcomes after exposure to IFN-beta 6 months before or during pregnancy. CONCLUSION: The prevalence of adverse pregnancy outcomes was not increased after IFN-beta exposure, when pregnancies of women with MS were stratified by maternal and newborn characteristics. The stratified results were similar to the unstratified results in the same population.

Pregnancy outcomes after exposure to interferon beta: a register-based cohort study among women with MS in Finland and Sweden.

BACKGROUND: Our aim was to estimate and compare the prevalence of adverse pregnancy outcomes among pregnant women with multiple sclerosis (MS) exposed to interferon beta (IFNB) and among women with MS unexposed to any MS disease-modifying drug (MSDMD). METHODS: This cohort study used Finnish (1996-2014) and Swedish (2005-2014) national register data. Women with MS having IFNB dispensed 6 months before or during pregnancy as the only medication were considered as IFNB exposed (only IFNB-exposed), whereas women with MS unexposed to any MSDMD were considered unexposed (MSDMD-unexposed). Prevalence was described and compared using log-binomial or logistic regression and adjusted for potential confounders including maternal age and comorbidity. RESULTS: Among 2831 pregnancies, 2.2% of the only IFNB-exposed and 4.0% of the MSDMD-unexposed women had serious adverse pregnancy outcomes [elective termination of pregnancy due to foetal anomaly (TOPFA), major congenital anomaly (MCA) in live, or stillbirth]. After adjustments, the prevalence of serious adverse pregnancy outcomes was lower among the only IFNB-exposed compared with the MSDMD-unexposed [relative risk 0.55, 95% confidence interval (CI) 0.31-0.96]. The prevalence of individual outcomes, including MCA, spontaneous abortions, and stillbirths was not increased with IFNB exposure. Women with MS exposed to IFNB appeared more likely to terminate their pregnancy for reasons other than foetal anomaly, compared with MSDMD-unexposed pregnant MS patients (odds ratio 1.71, 95% CI 1.06-2.78). CONCLUSION: In this large cohort study, no increase in the prevalence of adverse pregnancy outcomes was observed in women with MS exposed to IFNB compared with MS patients unexposed to any MSDMDs. This study together with other evidence led to a change in the labels of the IFNB products in September 2019 in the European Union, and IFNB use today may be considered during pregnancy, if clinically needed.

Rationale and design of a European epidemiological post-authorization safety study (PASS) program: rivaroxaban use in routine clinical practice.

BACKGROUND: Rivaroxaban is a highly selective factor Xa inhibitor approved for use in Europe for multiple indications. STUDY DESIGN AND METHODS: The European rivaroxaban epidemiological post-authorization safety study (PASS) program consists of seven complementary observational studies. For four of the studies, data are obtained from health-care databases in the UK, the Netherlands, Germany, and Sweden. These database studies describe patterns of rivaroxaban use and patient characteristics over time, and investigate safety and effectiveness outcomes in new users of rivaroxaban using a cohort analysis and nested case-control analysis. To put these results in context, safety outcomes are also analyzed in new users of standard of care. In addition, a modified prescription event monitoring study conducted in the early post-launch phase in primary care, and two specialist cohort event monitoring studies that investigated rivaroxaban use in the secondary care hospital setting, systematically collected drug utilization and safety data via questionnaires completed by health-care professionals in the UK. DISCUSSION: The European rivaroxaban epidemiological PASS is a comprehensive program of complementary studies generating evidence from patients treated in routine clinical practice that will expand our understanding of the risk-benefit profile of rivaroxaban.

The association between exposure to interferon-beta during pregnancy and birth measurements in offspring of women with multiple sclerosis.

BACKGROUND: Interferon-beta (IFN-beta) is a commonly used treatment for multiple sclerosis (MS). Current guidelines recommend cessation of treatment during pregnancy, however the results of past studies on the safety of prenatal exposure to IFN-beta have been conflicting. A large scale study of a population of MS women is therefore warranted. OBJECTIVES: To assess whether, among those born to women with MS, infants prenatally exposed to IFN-beta show evidence of smaller size at birth relative to infants which were not prenatally exposed to any MS disease modifying drugs. METHODS: Swedish and Finnish register data was used. Births to women with MS in Sweden and Finland between 2005-2014 for which a birth measurement for weight, height, and head circumference was available were included. The exposure window was from 6 months prior to LMP to the end of pregnancy. RESULTS: In Sweden, 411 pregnancies were identified as exposed to IFN-beta during the exposure window, and 835 pregnancies were counted as unexposed to any MS DMD. The corresponding numbers for Finland were 232 and 331 respectively. Infants prenatally exposed to interferon-beta were on average 28 grams heavier (p = 0.17), 0.01 cm longer (p = 0.95), and had head circumferences 0.14 cm larger (p = 0.13) in Sweden. In Finland, infants were 50 grams lighter (p = 0.27), 0.02 cm shorter (p = 0.92) and had head circumferences 0.22 cm smaller (p = 0.15) relative to those unexposed. CONCLUSIONS: This study provides evidence that exposure to IFN-beta during pregnancy does not influence birth weight, length, or head circumference.

Appropriateness of initial dose of non-vitamin K antagonist oral anticoagulants in patients with non-valvular atrial fibrillation in the UK.

OBJECTIVE: To evaluate the appropriateness of the initial prescribed daily dose of non-vitamin K antagonist oral anticoagulants (NOACs) according to label in patients with non-valvular atrial fibrillation (NVAF) in the UK. DESIGN: Population-based cross-sectional study. SETTING: UK primary care. POPULATION: 30 467 patients with NVAF and a first prescription for apixaban, dabigatran or rivaroxaban between January 2011 and December 2016. MAIN OUTCOME MEASURES: Percentage of patients prescribed a NOAC dose according to the European Union (EU) labels (appropriately dosed), and not according to the EU labels (inappropriately dosed-including both underdosed and overdosed patients); percentage of patients prescribed an initial NOAC dose according to renal function status. RESULTS: A total of 15 252 (50.1%) patients started NOAC therapy on rivaroxaban, 10 834 (35.6%) on apixaban and 4381 (14.4%) on dabigatran. Among patients starting NOAC therapy on rivaroxaban, 17.3% were eligible to receive a reduced dose compared with 12.8% of patients starting on apixaban and 53.8% of patients starting on dabigatran. The majority of patients were prescribed an appropriate dose according to the EU labels: apixaban 74.9 %, dabigatran, 74.4%; rivaroxaban, 84.2%. Underdosing occurred in 21.6% (apixaban), 8.7% (dabigatran), 9.1% (rivaroxaban). Overdosing was more frequent for dabigatran (16.9%) than for rivaroxaban (6.6%) or apixaban (3.5%). There was a trend towards dose reduction with increasing renal impairment. Among patients with severe renal impairment, the majority received a reduced dose NOAC: apixaban, 91.1%, dabigatran, 80.0%, rivaroxaban, 83.0%. CONCLUSION: Between 2011 and 2016, the majority of patients starting NOAC therapy in UK primary care were prescribed a daily dose in line with the approved EU drug label. Underdosing was more than twice as common among patients starting on apixaban than those starting on dabigatran or rivaroxaban. Research into the patient characteristics that may influence inappropriate underdosing of NOACs in UK primary care is warranted.

Ascertainment and validation of major bleeding events in a primary care database.

PURPOSE: The purpose of the study is to evaluate the impact of validation on the identification of major bleeding events in The Health Improvement Network (THIN) database in patients receiving anticoagulant therapy. METHODS: Patients aged 2 to 89 years with a first prescription for an anticoagulant (rivaroxaban or warfarin) between 2012 and 2015 were identified in THIN. Major bleeding events, defined as bleeding events necessitating hospitalization or referral to accident and emergency services or a specialist clinic, were identified using a 2-step ascertainment process based on read codes only, and then validated using a 2-step process requiring manual review of patients' records. RESULTS: The positive predictive value for the ascertainment of major intracranial (IC) bleeds using only read codes was 96.9%, compared with 70.4% for gastrointestinal (GI) bleeds and 64.1% for urogenital (UG) bleeds. The incidence rate of major IC bleeding events was therefore similar when it was calculated before and after validation (0.32 per 100 person-years and 0.31 per 100 person-years, respectively). The incidence rate of major GI bleeds identified using read codes alone was reduced following validation from 2.05 to 0.94 per 100 person-years, and that of major UG bleeds decreased from 2.45 to 1.11 per 100 person-years. CONCLUSIONS: Major GI and UG bleeding events ascertained from THIN using read codes require validation using additional information to prevent outcome misclassification. The absence of validation may lead to overestimated incidence rates of major bleeding for GI and UG bleeds.