Individualized therapy trials: navigating patient care, research goals and ethics

‘Individualized therapy’ trials (sometimes called n -of-1 trials) use patients as their own controls to evaluate treatments. Here we divide such trials into three categories: multi-crossover trials aimed at individual patient management, multi-crossover trial series and pre–post trials. These trials all customize interventions for patients; however, the latter two categories also aim to inform medical practice and thus embody tensions between the goals of care and research that are typical of other types of clinical trials. In this Perspective, we discuss four domains where such tensions play out—clinical equipoise, informed consent, reporting and funding, and we provide recommendations for addressing each.