Evaluating the effects of treatment switching with randomization as an instrumental variable in a randomized controlled trial

The purpose of this study was to utilize simulated data based on an ongoing randomized clinical trial (RCT) to evaluate the effects of treatment switching with randomization as an instrumental variable (IV) at differing levels of treatment crossovers, for continuous and binary outcomes. Data were analyzed using IV, intent-to-treat (ITT), and per protocol (PP) methods. The IV method performed the best, since it provided the most unbiased point estimates, and it had equal or higher power and higher coverage probabilities compared to the ITT estimates, and because a PP analysis can be biased due to its exclusion of non-compliant patients.