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The first non-vitamin K antagonist oral anticoagulant (NOAC) was approved for stroke prevention in patients with atrial fibrillation (AF) in the EU in 2011,1 and NOACs are now the most widely prescribed class of oral anticoagulants for these patients worldwide.2 In the last decade, real-world studies of patients with AF treated with NOACs have been accumulating. For instance, as of April 2019, over 4 million patients were included, or were due to be included, in observational studies of NOACs in patients with AF (note that some individual patients may have been included in multiple studies). Real-world studies provide substantial evidence to supplement data from the pivotal phase III randomized controlled trials (RCTs) comparing NOACs with warfarin for stroke prevention. For example, the safety and efficacy of rivaroxaban was evaluated in the prospective, real-world, phase IV study XANTUS, which was included on the European Medicines Agency label of rivaroxaban due to its robust methodology.3,4 Further valuable real-world evidence (RWE) supporting the benefits of rivaroxaban in high-risk patients with AF, such as those with diabetes and/or renal impairment, is derived from recent US and German claims database analyses.5-11 More details on the recent RWE studies of rivaroxaban in high-risk patients with AF can be found in the newsletters on diabetes and worsening renal function.
Real-world studies utilize a wide range of research methodologies and data sources, and can broadly be categorized as non-interventional studies; patient registries; administrative and claims database analyses; electronic health record studies; and patient surveys.12
Real-world data can be collected either prospectively (primary data collection) or retrospectively (use of secondary data that were initially collected for other purposes).12 With appropriate trial design, all types of real-world study can provide valuable insights that are more reflective of routine clinical practice than RCTs.12 They can also supply a greater quantity of data from larger patient populations, and provide benefit–risk insights to inform guidelines, or economical insights for cost–benefit analyses to support guideline and reimbursement decisions.12
Although the heterogeneity of patient populations can be an advantage, the heterogeneity of the data generated presents challenges to interpretation. Unlike RCTs, observational studies tend to be non-randomized and are, therefore, susceptible to bias due to confounding factors between treatment arms; additionally, quality control surrounding data collection may not be as rigorous as in RCTs.12,14 RWE studies are most valuable in providing insights that are reflective of clinical practice, and so can aid clinical decision-making. When evaluating the quality of real-world data, it is important to consider several factors, such as the hypothesis, data source, study population, treatment administered, length of follow-up, outcomes assessed and availability of sensitivity analyses data.14
Prospective and retrospective real-world studies can provide a wealth of information to confirm RCT data in more representative patient populations and provide further insights into practical aspects of clinical decision-making, such as patient quality of life and healthcare resource utilization. Demonstrating the benefits of a drug in routine clinical practice might reassure the patient that the drug has been studied in patients like them. If interpreted correctly, consistent results from real-world studies and RCTs can further provide reassurance about the safety and effectiveness of a drug in clinical practice.