Non-randomized and randomized trials

Although good quality randomized controlled trials provide high level evidence for informing practice, they can be difficult to undertake within surgery. Non-randomized trials, whilst easier to conduct, often contain many biases that make it difficult to establish causation. It is no surprise, therefore, that much surgical practice is established through little evidence of efficacy, often being driven by external factors such as industry and personal preference. The ways in which surgical practice has evolved despite the evidence will be discussed. The difficulties of undertaking randomized and non-randomized trials will also be outlined.