A mega-trial, also known as a large simple trial, is a type of clinical trial that involves a very large number of participants. These trials are often conducted to evaluate the effectiveness of a particular treatment or intervention, and they are typically designed to provide a high level of statistical power, which means that they are able to detect even small differences between the treatment and control groups.

One example of a mega-trial is the Clinical Outcomes Utilizing Revascularization and Aggressive DruG Evaluation (COURAGE) trial. This trial involved over 2,300 participants and was designed to evaluate the effectiveness of revascularization (a surgical procedure that improves blood flow to the heart) in combination with aggressive medical therapy (such as the use of drugs to control cholesterol and blood pressure) in patients with chronic stable angina. The results of the COURAGE trial showed that revascularization did not provide any additional benefit to patients when compared to aggressive medical therapy alone.

Another example of a mega-trial is the Diabetes Prevention Program (DPP) trial. This trial involved over 3,000 participants and was designed to evaluate the effectiveness of lifestyle interventions (such as diet and exercise) in preventing the development of type 2 diabetes in individuals who were at high risk for the disease. The results of the DPP trial showed that lifestyle interventions were effective at reducing the incidence of type 2 diabetes by 58% compared to placebo.

Mega-trials are a valuable tool in the field of clinical research, as they are able to provide high-quality evidence about the effectiveness of treatments and interventions. They are often used to evaluate the effectiveness of treatments for common conditions, such as heart disease and diabetes, and can help to guide clinical practice and inform decision-making.