When can nonrandomized studies support valid inference regarding effectiveness or safety of new medical treatments?

View Abstract

The randomized controlled trial (RCT) is the gold standard for evaluating the causal effects of medications. Limitations of RCTs have led to increasing interst in using real-world evidence (RWE) to augment RCT evidence and inform decision-making on medications. Although RWE can be either randomized or nonrandomized, nonrandomized RWE can capitalize on the recent proliferation of large healthcare databases and can often answer questions that cannot be answered in randomized studies due to resource constraints. However, the results of nonrandomized studies are much more likely to be impacted by confounding bias, and the existence of unmeasured confounders can never be completely ruled out. Furthermore, non-randomized studies require more complex design considerations which can sometimes result in design-related biases.We discuss questions that can help investigators or evidence consumers evaluate the potential impact of confounding or other biases on their findings: Does the design emulate a hypothetical randomized trial design? Is the comparator or control condition appropriate? Does the primary analysis adjust for measured confounders? Do sensitivity analyses quantify the potential impact of residual confounding? Are methods open to inspection and (if possible) replication? Designing a high-quality nonrandomized study of medications remains challenging and requires broad expertise across a range of disciplines, including relevant clinical areas, epidemiology, and biostatistics. The questions posed in this paper provide a guiding framework for assessing the credibility of nonranomzied RWE and could be applied across many clinical questions.

Investigators
Abbreviation
Clin Pharmacol Ther
Publication Date
2021-04-07
Pubmed ID
33826756
Medium
Print-Electronic
Full Title
When can nonrandomized studies support valid inference regarding effectiveness or safety of new medical treatments?
Authors
Franklin JM, Platt R, Dreyer NA, London AJ, Simon GE, Watanabe JH, Horberg M, Hernandez A, Califf RM