Confidence intervals and p-values in urology. Interpretation and misinterpretation

Confidence intervals and p-values are widely used in the urological literature to describe and interpret outcomes. However, several readers, authors and reviewers are unfamiliar with the true interpretation of these values. P-values determine statistical significance of data. Confidence intervals characterize a range of values in which the true effect size is suggested to be with a given degree of certainty. An independent but complementary interpretation of both values is important in studies with and without statistical significance. Based on a clinical case scenario this article discusses the interpretation as well as common pitfalls in interpretation of p-values and confidence intervals. An accurate assessment of these statistical cornerstones is fundamental for a correct interpretation of the urological literature and thus important aspects of evidence-based urology.