Treatment fidelity in clinical trials

In the context of clinical trials, treatment fidelity (TF) has traditionally referred to the extent to which an intervention or treatment is implemented by the clinicians as intended by the researchers who designed the trial. Updated definitions of TF have included an appropriate design of the intervention that was performed in a way that is known to be therapeutically beneficial. This requires careful attention to three key components: (1) protocol and dosage adherence, (2) quality of delivery, and (3) participant adherence. In this viewpoint, we describe several cases in which TF was lacking in clinical trials and give opportunities to improve the deficits encountered in those trials. We feel that along with quality, risk of bias, and certainty of evidence, TF should be considered an essential element of the veracity of clinical trial.