Randomized controlled trials (RCTs) are considered to be the gold standard for determining a causal effect of medical interventions. To achieve this aim, possible confounding factors must be avoided. This implies excluding many patients from participating in the trial, for example, patients with concomitant conditions. A negative consequence of these exclusions, however, is limited generalizability. Studying the artificially uniform participant group, you will be able to determine a causal effect, but you will know much less about real-life treatment outcomes in the population where the intervention actually will be used.
Further artificiality is created by the written informed consent procedure, which excludes even further patients from participating in the trial. Moreover, because they know they participate in a clinical trial, participants may change their behavior.
All this points to the importance of so-called pragmatic randomized controlled trials. In such trials, the effectiveness of two approved and routinely prescribed medicines are compared in normal clinical practice. This avoids most of the artificiality of RCTs and significantly improves generalizability and practical clinical relevance. Randomization is still required for scientific purposes, however, and written informed consent is an ethical obligation.
The demand for written informed consent is an obstacle to pragmatic trials. By creating, once again, artificial selection of patients, results continue to be less generalizable, which detracts from the whole point of conducting pragmatic trials. In a recent paper in the BMJ, twelve authors, among them, Stefan Eriksson at CRB, therefore argue that “EU clinical trial regulations should be revised to allow the waiver or modification of informed consent in low risk pragmatic trials.”
Some would consider this suggestion to be controversial. We need to keep in mind, however, the extremely low risks of studies that compare standardly prescribed medicines in normal clinical practice. We need to balance that low risk against the enormous social value of generalizable findings in evidence-based medicine.
Dal-Ré, R. et al. Low risk pragmatic trials do not always require participants’ informed consent. BMJ 2019;364:l1092