RWE 101 – Study Designs

Real-world evidence (RWE) studies are becoming increasingly important in healthcare decision-making. There are various study designs used to generate RWE, each with their unique benefits:
[1] Cohort Studies: Cohort studies are observational in nature, where two or more groups (cohorts) distinguished by their exposure to a certain factor (like a medical treatment or lifestyle choice) are followed and assessed to determine the effect of that exposure. These studies are advantageous in studying rare outcomes, multiple outcomes, or outcomes that take a long time to develop.
[2] Case-Control Studies: These studies start with the outcome and then look backward to find the exposure. They’re efficient for studying rare diseases or diseases with a long latency period, as well as multiple exposures. However, they may not be as reliable as cohort studies due to potential recall bias.
[3] Cross-Sectional Studies (Prevalence Studies): These studies observe a defined population at a single point in time or time interval. They’re useful in understanding the burden of a disease in a population, assessing public health needs, and planning healthcare services.
[4] Registry-Based Studies: These are observational studies where data are collected prospectively or retrospectively for patients with a particular condition or who are undergoing a specific procedure. Registry-based studies provide long-term, real-life data about prognosis, adverse events, quality of life, and cost-effectiveness.
[5] Pragmatic Clinical Trials (PCTs): Unlike traditional randomized clinical trials, PCTs are designed to determine the effectiveness of interventions in real-world routine practice conditions. They often include a more diverse patient population, multiple care settings, and less rigid protocols.
[6] Retrospective Studies: This involves analyzing existing datasets (like EHRs or insurance claims databases) to find associations or trends. This is also known as secondary use of existing data. While these are generally quicker and less expensive, they are subject to the limitations of the existing data, which may not have been collected for research purposes.
[7] Prospective Observational Studies: In these studies, subjects are followed over time with data collected about various factors that might influence the outcome of interest. These studies are useful in understanding the natural history of disease and the effectiveness of different treatments in the real world. These studies usually include both secondary data (data collected for a different purpose) and primary data (data collected specifically for the purposes of the study).

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