"Real-world data," as defined by the US Food and Drug Administration, are data relating to the health status of a patient or the delivery of healthcare services. Common sources of real-world data include electronic health records, administrative claims, patient-reported outcomes, patient-generated health data, and medical product and device registries, as well as databases relating to environmental factors or social determinants of health. Real-world data can be used to support a number of activities in pragmatic clinical trials, such as patient identification and recruitment, monitoring of outcomes, and ascertainment of endpoints.

Most real-world data are considered secondary data sources when used for research, because they were originally generated for another purpose and thus reflect the context of that activity (hence their "real-world" nature). Therefore, it is necessary to ensure that real-world data are fit for use before including them in a study. (See the Assessing Fitness for Use of Real-World Data Sources chapter of the Living Textbook.) This chapter outlines strategies for obtaining real-world data for use in research.