Alternative approaches to tuberculosis treatment evaluation: the role of pragmatic trials.

Clinical trials are sometimes classified as being explanatory or pragmatic, although they are rarely reported in that way. Explanatory trials may seek to investigate the efficacy of new treatments by imposing strict limitations on many aspects of trial design, including, for example, recruiting only those patients who are most likely to respond. In contrast, the objective of pragmatic trials is to assess whether treatments work in conditions more appropriate to routine practice. This dichotomy is, however, over-simplistic; there is usually a continuum, which is a consequence of there being many areas of trial design that can vary between the extremities of the explanatory and pragmatic approaches. The PRECIS (pragmatic-explanatory continuum indicator summary) wheel based on 10 domains, which include inclusion criteria, flexibility of delivery of the intervention and intensity of follow-up, has been proposed as a way of enabling researchers to assess the extent to which the trials they are designing could be considered explanatory or pragmatic. In this article, we consider how the PRECIS tool can be applied to trials of tuberculosis treatment. In view of the well-recognised delay in getting results from well-conducted clinical trials into practice, we would suggest that if more pragmatic trials were to be conducted, physicians would better understand the implications of the results for their own practice and be more ready to adopt new treatments.