When and how to include vulnerable subjects in clinical trials

There has been a good deal of discussion in the literature regarding which subjects are vulnerable in the context of clinical trials. There has been significantly less discussion regarding when and how to include vulnerable subjects in clinical trials. This lack of guidance is a particular problem for trials covered by the US regulations, which mandate strict requirements on the inclusion of three groups: pregnant women/fetuses, prisoners, and children. For the past 30 years, funders, investigators, and institutional review boards have frequently responded to these regulations by excluding pregnant women/fetuses, prisoners, and children from clinical trials. More recent work has emphasized the extent to which a default of exclusion can undermine the value of clinical trials, especially pragmatic trials. A default of exclusion also has the potential to undermine the interests of vulnerable groups, in both the short and the long term. These concerns raise the need for guidance on how to satisfy existing US regulations, while minimizing their negative impact on the value of clinical trials and the interests of vulnerable groups. The present manuscript thus describes a six-step decision procedure that institutional review boards can use to determine when and how to include vulnerable subjects in clinical trials, including pragmatic trials, that are covered by US regulations.