How to deal with measures of association: a short guide for the clinician

Abstract

When reading medical literature as a clinician, many different measures of association are presented. To judge whether results of studies can be applied to clinical practice, it is essential to understand and to be able to interpret the measure of association reported in the article. In this paper, we will present how to deal with the most commonly used measures of association including the risk and rate difference, number needed to treat, risk and rate ratio, hazard ratio and odds ratio. By means of examples, we will discuss the different measures of association for the three main study designs used in clinical research: randomized controlled trial, observational cohort study and case-control study.