title: Statistical significance and clinical relevance: the importance of power in clinical trials in dermatology.
abstract: When evaluating the validity of a study, the reader must consider both the clinical and statistical significance of the findings. A study that claims clinical relevance may lack sufficient statistical significance to make a meaningful statement. Conversely, a study that shows a statistically significant difference in 2 treatment options may lack practicality. The concept of power of a clinical trial refers to the probability of detecting a difference between study groups when a true difference exists. We will discuss statistical power by examining studies too small to identify important differences, studies so large as to identify differences that are not clinically significant, difficult-to-design studies without very large patient populations, and those studies with both adequate power and clinically relevant findings. Dermatologists should not focus on small P values alone to decide whether a treatment is clinically useful; it is essential to consider the magnitude of treatment differences and the power of the study.
authors.affiliation: Center for Dermatology Research, Department of Dermatology, Wake Forest University School of Medicine, Winston-Salem, NC 27157-4071, USA.
authors.forename: Sachin S
authors.initials: SS
authors.lastname: Bhardwaj
authors.forename: Fabian
authors.initials: F
authors.lastname: Camacho
authors.forename: Amy
authors.initials: A
authors.lastname: Derrow
authors.forename: Alan B
authors.initials: AB
authors.lastname: Fleischer
authors.forename: Steven R
authors.initials: SR
authors.lastname: Feldman
mesh_terms: D002986:Clinical Trials as Topic / Q000706:statistics & numerical data*; D003627:Data Interpretation, Statistical; D003880:Dermatology; D006801:Humans