Crossover and Early Failure in Surgical Trials

Unplanned crossover of subjects from one treatment arm to another in randomized surgical trials is a relatively common occurrence and can be due to multiple factors, including patient choice, variance in surgical technical ability, or early treatment failure. This failure to adhere to the originally assigned treatment arm can create difficulties in the analysis and interpretation of trial results and may substantially impact the validity of the trial. Studies can be designed to reduce the risk of unplanned crossover using techniques such as investigator training and education, patient selection, and patient education. If crossover occurs, various methods of analysis have been used to address crossover in clinical trials, each with potential advantages and disadvantages. If there is significant crossover, the data may be better interpreted or presented as an observational study, rather than as a randomized clinical trial. Readers of scientific literature should be aware of the potential impact of crossover in surgical trials.