
Real-world evidence (RWE) in clinical trials is changing drug development by using Real-World Data (RWD) from various sources to enable researchers to gather valuable insights into how drugs work in a wide range of populations. This move toward RWE not only deepens our understanding of treatment effects and patient outcomes, but also speeds up the drug development process, making it more efficient and centred around patients. In this article, we explore the role of RWE in clinical trials, discussing its benefits, challenges, and the regulatory environment that supports its use in healthcare decision-making. We also clarify how RWE relates to traditional clinical trial data, where each approach is most useful, and why they are typically most valuable when used together rather than treated as direct substitutes.
Real-World Evidence is the clinical evidence generated through the analysis of Real-World Data (RWD). Unlike traditional clinical trial data, which is collected under highly controlled conditions to ensure internal validity, RWE uses RWD to demonstrate the actual experiences of patients in everyday environments, capturing a broader range of patient behaviours, treatment responses, and health outcomes.
Real-World Data is patient health-related data collected outside of traditional clinical trials. RWD can come from a range of sources including;
The diversity in data sources allows for a broader understanding of patient health as RWD can capture the variability of real-life patient experiences, enabling the identification of trends and patterns that might not otherwise have been captured in a traditional clinical trial.
‘Fit for purpose’ means the data are suitable for the specific question being asked. A large dataset is not automatically useful if it does not capture the right population, exposure timing, outcomes, follow-up period, or key confounders. The relevant standard is therefore not just whether the data exist, but whether they are sufficiently complete, traceable, and analytically appropriate for the intended use.
This matters because the same source may be useful for one purpose and weak for another. Claims data may support utilisation analysis well, for example, but may be less suitable for clinical endpoints that depend on detailed disease severity or laboratory context. Assessing how suitable the data means checking whether the source, design, and analysis plan match the evidentiary question from the outset.
There are several benefits to using RWE in clinical trials. Let’s look at these in more detail:

Traditional RCTs often require extensive recruitment efforts and prolonged follow-up periods. RWE, however, can help identify patient populations that are most likely to benefit from the investigational treatment, based on real-world usage patterns and outcomes. This targeted approach to recruitment not only reduces recruitment time but also enhances the relevance and applicability of trial results. In addition, because of the virtual trial setting, it is easier to recruit patients regardless of their location as they do not have to visit study sites.
In practice, traditional clinical trial data and real-world evidence often answer different but related questions. Randomised controlled trials are typically designed to test efficacy under defined conditions and support stronger causal inference, while RWE is more often used to understand how treatments perform across broader populations, routine care settings, and longer follow-up periods.
One reason these evidence types can lead to different findings is bias. In observational RWD studies, treatment allocation is not random, so the patients receiving one treatment may differ systematically from those receiving another before the treatment effect itself is considered. Confounding, missing variables, differences in follow-up, coding limitations, treatment switching, and inconsistent outcome capture can all influence the results. This does not make RWE unhelpful, but it does mean findings should be interpreted in light of the design and data source rather than treated as automatically equivalent to randomised evidence. Common sources of bias in RWE studies include selection bias, confounding, missing data, inconsistent outcome capture, and differences in follow-up between patient groups. These limitations do not make RWE unusable, but they do mean findings need to be interpreted in light of the data source, study design, and analytical approach.
Pragmatic trials sit somewhere between highly controlled explanatory trials and fully observational real-world evidence. They are designed to test how an intervention performs in conditions closer to usual clinical practice, often using broader eligibility criteria, routine care delivery, and outcomes that are more directly relevant to everyday settings. For teams working with RWE, pragmatic trials can therefore act as a bridge between tightly controlled randomised evidence and real-world data, improving the practical relevance of trial findings without abandoning prospective trial methodology.
Not usually as a direct one-for-one replacement. Randomised clinical trials remain important for reducing selection bias and supporting causal interpretation, while real-world data are more often used to complement trial evidence or support questions that are difficult to answer through a traditional trial alone. In practice, whether RWD can stand in for a traditional trial depends on the question being asked, the quality and completeness of the data, and how much uncertainty decision-makers can accept.
As much as there are benefits to RWE, there are also challenges and it is not always straight forward for drug developers to incorporate RWE into their study analysis. Here are some key challenges to RWE:
As mentioned, regulatory agencies are open to the use of RWE to help drug developers demonstrate a therapy’s safety and efficacy. In this section we will review the regulatory stance on RWE in more detail.
The FDA has been proactive in integrating RWE into its regulatory processes, recognising its potential to enhance drug development and regulatory decision-making. The FDA's framework for evaluating RWE encourages the use of RWE to support regulatory submissions, including new drug approvals and post-approval studies. The framework emphasises several key principles:
Purpose and Scope
The FDA's RWE framework is designed to evaluate real-world evidence to support new drug indications, fulfil post-approval study requirements, and make other regulatory decisions, in line with the 21st Century Cures Act.
Data Quality and Study Design
It emphasises the need for high-quality, reliable real-world data and robust, transparent study designs. The framework encourages diverse data sources and methodologies, requiring pre-specified protocols to ensure credibility and reproducibility.
Public Engagement and Transparency
The FDA aims to share insights from RWE studies through public workshops and case studies to promote understanding and acceptance of RWE in regulatory contexts.
Submission and Review Process
A structured process for submitting RWE proposals is outlined, where the FDA collaborates with sponsors to ensure studies meet regulatory standards.
In practice, the most important point is less about any single framework document and more about the direction of travel: regulators increasingly expect RWE to be credible, question-led, and methodologically transparent.
The EMA has also embraced the potential of RWE, particularly through its wider regulatory science and evidence-generation work, including ongoing efforts to improve access to and use of real-world data in medicines regulation. That work underscores the importance of leveraging RWE for a deeper understanding of diseases, treatment pathways, and the real-life use of medicines. The EMA focuses on several key areas
Innovate Clinical Trials
The EMA aims to leverage RWD to include diverse populations and endpoints in clinical trials. They are focused on modernising oversight for decentralised trials and developing robust digital endpoints.
Enhance Benefit-Risk Assessment
The EMA emphasises the inclusion of patient preferences in benefit-risk assessments and is developing guidance for incorporating patient-reported outcomes to ensure patient-centric evaluations.
Support Special Populations
Using RWD, the EMA seeks to accelerate access to treatments for special populations, addressing unmet medical needs more effectively.
Advance Modelling and Simulation
The EMA is advancing the use of RWD to improve predictive tools and decision-making through enhanced modelling and simulation techniques.
Utilise Digital Technology and AI
To analyse large datasets, the EMA is leveraging digital tools and artificial intelligence. They are establishing a digital innovation lab and developing comprehensive guidelines for AI use in regulatory processes.
Improve Patient Access
The EMA integrates Health Technology Assessment (HTA) and payer evidence early in drug development to improve patient access. They also utilise RWD for post-licensing evidence generation and the detection of drug safety issues.
Strengthen Network Competence
The EMA is building a sustainable platform for accessing and analysing healthcare data across the EU, ensuring data quality and strengthening the regulatory network's capability to handle big data submissions.
Across both FDA and EMA contexts, the practical takeaway is similar. RWE can support regulatory and post-approval decision-making, but it is most persuasive when the research question, data provenance, study design, and analytical limitations are clearly defined.
Capturing and analysing RWD would not be possible if it was not for the advancements in digital technologies. Below we review these technologies in more detail and how they have made RWE possible.
Wearable devices and mobile health apps have revolutionised the collection of patient health data, offering opportunities for real-time monitoring and continuous data collection. These technologies include fitness trackers, smart watches, and biosensors that can track a wide range of physiological parameters such as heart rate, activity levels, sleep patterns, and even glucose levels. The constant stream of data generated by these devices provides a detailed picture of a patient's health and lifestyle, offering valuable insights for RWE studies.
Mobile health apps complement wearable devices by providing platforms for patients to manage their health conditions, track medication adherence, and communicate with healthcare providers. These apps can collect a wide array of data, from self-reported symptoms and medication intake to data collected via integrated smartphone sensors. The combination of wearable devices and mobile health apps enables the collection of comprehensive and continuous health data, which can be used to enhance the precision and relevance of RWE studies.
The integration of big data analytics and artificial intelligence (AI) is transforming the collection and analysis of real-world data (RWD). Big data analytics involves processing vast amounts of data rapidly, enabling researchers to uncover patterns and correlations that inform healthcare decision-making. Advanced analytics techniques, such as machine learning and natural language processing, can handle the complex and unstructured nature of RWD. This is particularly useful when extracting meaningful insights that may not be apparent through traditional analysis methods.
Artificial intelligence, particularly machine learning algorithms, plays a crucial role in analysing RWD by identifying trends, predicting outcomes, and generating actionable insights. For example, AI can be used to predict disease progression, treatment responses, and potential adverse events based on historical data. The combination of big data analytics and AI enhances the precision and scalability of RWE studies, allowing for the analysis of larger and more diverse patient populations.
These are digital versions of patients' paper charts, offering comprehensive records of medical history, diagnoses, treatment plans, immunisation dates, and test results. The digitisation of patient records has been pivotal in streamlining the collection of RWD, making it more accessible for research purposes. EHRs provide a wealth of data that can be used to generate RWE, including information on patient demographics, comorbidities, treatment outcomes, and healthcare utilisation patterns.
Pfizer's use of Real-World Evidence (RWE) to expand the label of IBRANCE® (palbociclib) is a notable example of how RWE can influence regulatory decisions and broaden treatment options. Initially approved in 2015 for treating HR+/HER2- advanced or metastatic breast cancer in postmenopausal women, Pfizer sought to expand its use to include male patients, a population not included in the initial clinical trials. To achieve this, Pfizer conducted an observational study using real-world data from electronic health records (EHRs) to demonstrate the effectiveness of IBRANCE® in men with breast cancer. Based on the real-world evidence presented, the FDA expanded the label of IBRANCE® in 2019 to include male patients, marking a significant instance where RWE directly influenced drug labelling and expanded treatment options for a broader patient population.
Novartis leveraged RWE to support the real-world effectiveness and safety of Entresto® (sacubitril/valsartan), a treatment for heart failure. Clinical trials had already demonstrated its benefits over enalapril in reducing the risks of death and hospitalisation due to heart failure. After approval, Novartis continued to gather real-world data from patients using Entresto® through registries and observational studies. This data provided ongoing evidence of the drug's effectiveness and safety in a broader, more diverse patient population outside the controlled environment of clinical trials. The real-world data supported the findings from the clinical trials and helped further establish the real-world effectiveness and safety profile of Entresto®, reinforcing its position in treatment guidelines and clinical practice for heart failure.
AstraZeneca's TAGRISSO® (osimertinib) is a medication used in treating non-small cell lung cancer (NSCLC) with specific mutations. Its approval and subsequent label expansions have been supported by a combination of clinical trial data and RWE. Real-world evidence has been particularly useful in demonstrating the drug's effectiveness in real-world settings, including its use in populations and scenarios not fully covered in clinical trials. This includes data on long-term survival rates, quality of life, and effectiveness in treating central nervous system (CNS) metastases. The integration of RWE has helped provide comprehensive evidence of TAGRISSO®'s benefits, supporting its widespread adoption in clinical practice for the treatment of NSCLC with EGFR mutations.
The unprecedented global effort to develop, approve, and monitor COVID-19 vaccines has relied heavily on RWE. This includes post-authorisation safety and effectiveness studies conducted in real-world populations. Governments and pharmaceutical companies have utilised health records, vaccine registries, and other sources of health data to monitor the safety and effectiveness of COVID-19 vaccines in the general population. This ongoing collection of RWE is crucial for identifying rare side effects, understanding long-term immunity, and making informed decisions about booster doses. The real-world evidence gathered has played a key role in ensuring public confidence in the vaccines, guiding public health policies, and adapting vaccination strategies based on emerging data about vaccine performance against variants of the virus.
In summary, RWE provides a comprehensive picture of how treatments perform across diverse patient populations and healthcare settings. This makes RWE a critical tool for understanding the effectiveness, safety, and value of medical interventions in real-world practice.
The insights gained from RWE can inform clinical guidelines, support regulatory decisions, and enhance patient care by aligning treatment approaches with real-world patient needs and experiences. When used carefully, RWE can extend, contextualise, and strengthen the evidence base around clinical development rather than trying to stand apart from it.
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