Twins in clinical trials

Twin research is integral in epidemiological research to understand the role of genetics and the environment related to health and disease. Despite the methodological advantages, the use of twins as participants in interventional randomized controlled trials (RCTs) are limited. Cotwin designs can increase statistical power while also having the added advantage of involving smaller sample sizes. Twin RCTs may also control for potential confounding factors such as genetic makeup and age. This chapter discusses the value of twins in interventional research and the advantages and limitations of conducting twin RCTs.