Common pitfalls in the conduct of clinical research

Recently, paradigm shift from expert opinion towards evidence-based medicine has occurred encouraging physicians to base their treatment decisions on the best available research evidence. In the hierarchy of evidence randomized clinical trials [level 1 evidence] are considered of the highest quality [least biased] while non-randomized studies represent lower levels [levels 2-4]. Several pitfalls in the design and conduct of clinical research include: lack of randomization, lack of concealment, lack of blinding, and errors in hypothesis testing [type I and II errors]. A basic understanding of these principles of research will empower both investigators and readers when applying the results of research to clinical practice