TY - JOUR T1 - What is an Odds Ratio? What does it mean? JF - Evidence Based Nursing JO - Evid Based Nurs SP - 98 LP - 99 DO - 10.1136/eb-2015-102206 VL - 18 IS - 4 AU - Allison Shorten AU - Brett Shorten Y1 - 2015/10/01 UR - http://ebn.bmj.com/content/18/4/98.abstract N2 - When we read the results of healthcare research, we often read about relationships or associations between different treatments and their outcomes for patients. Health outcomes can be improved with the use of different types of medications, engagement in health education programmes and changes in lifestyle factors such as targeted improvements in nutrition or reduction in smoking. Depending on the research design, we can use statistical tools to assist us in identifying the most effective healthcare interventions, with the aim of achieving the best health outcome for patients. This can help us make decisions about which treatments we should provide or which public health programmes should be funded, in the hope that we can improve the overall health of our patients and the communities we serve. We often see odds ratios (ORs) being used in research to explain whether interventions contribute to improvements in health. They are used to help researchers demonstrate associations between interventions and outcomes in both positive and negative directions.To explain how ORs are calculated and what they mean, we will use two examples. Let's first consider a hypothetical example of a randomised controlled trial (RCT). We are often interested in programmes that will reduce rates of smoking in the community. In particular, we often see studies that focus on reducing the rates of smoking in pregnant women, with the aim of achieving health improvements for both women and their newborn babies. Let's consider a study designed to test a smoking cessation programme for pregnant women. Table 1 provides a summary of the hypothetical results.View this table:In this windowIn a new windowTable 1 Hypothetical data on cessation of smoking among pregnant womenFrom table 1, we see that 200 women were randomised to either the intervention group (where pregnant women received the smoking cessation programme), or a control group (pregnant women … ER -