IOSR Journal of Humanities And Social Science (IOSR-JHSS) Volume 26, Issue 4, Series 10 (April. 2021) 56-58 e-ISSN: 2279-0837, p-ISSN: 2279-0845. www.iosrjournals.org DOI: 10.9790/0837-2604105658 www.iosrjournals.org 56 |Page Equivalent risk, different decision Carina Ferreira 1 , Teresa Abreu 1 , José M. Pereira 2 , Mário Basto 1 1 (Higher School of Technology/ Polytechnic Institute of Cávado and Ave, Portugal) 2 (Higher School of Management/ Polytechnic Institute of Cávado and Ave, Portugal) Abstract: Background: The relative risk reduction (RRR), the absolute risk reduction (ARR), and the number needed to treat or screen (NNT) are measures usually used to communicate the advantages of medical screening. Properly informed decision-making requires an understanding of these statistics by both health professionals and patients. However, even when this knowledge holds, the perception of the benefits of these three measures may be distinct, since they are translated by numbers of different magnitudes. The objective of this study is to assess whether health professionals and patients understand or are influenced by the risk presentation format in the decision to screen. Materials and Methods: A question from a questionnaire shared online assessed the impact of those statistics on health professionals and the general population. Results: The results point to a greater impact when information is conveyed as the RRR. The overestimation of RRR is slightly more pronounced in health professionals. The NNT had the least impact and is possibly the least understood. Conclusion: The different perception of benefits that arises from the risk format used, skew the decision- making process and may impact the health of patients. It is necessary to improve statistical education among health professionals and the general population. Key Words: Informed decision-making; Relative risk reduction (RRR); Absolute risk reduction (ARR); Number needed to treat (NNT). --------------------------------------------------------------------------------------------------------------------------------------- Date of Submission: 14-04-2021 Date of Acceptance: 28-04-2021 --------------------------------------------------------------------------------------------------------------------------------------- I. INTRODUCTION Health professionals and patients must correctly interpret numbers and statistics in healthcare so that an informed decision can take place. According to several authors, many physicians and patients do not understand what some health statistics mean 1,2,3,4 . This problem is often created by the use of non-transparent information, whether intentional or not 1 . This lack of statistical literacy can impact and have consequences not only on the decision and health of patients but may also affect the costs of health systems. Every treatment or medical procedure has risks and must be balanced against the benefits. People must understand the risks and benefits properly. But is this what happens? The benefits of health screening processes are usually communicated using the relative risk reduction (RRR), the absolute risk reduction (ARR), or the number of people needed to treat to obtain a benefit (NNT). It is necessary to understand those three concepts properly to make an informed decision. The ARR is the percentage of patients who stop experiencing a particular event and do not require knowledge of the baseline risk. The RRR is the ratio between the ARR and the baseline risk. Without it, its value can be misleading and may lead to an overestimation of the benefits since it is generally translated by a large number. The NNT, which is the inverse of the ARR, is sometimes used, but this form of risk presentation is generally poorly understood 2 . Some definitions of the terminology used in risk communication are clarified by Siwek and Newman 5 , to increase and assist in the informed decision process of patients. The following example allows a better understanding of these concepts: A clinical trial with a new drug is being tested to prevent disease A. Two groups of 100 individuals each are built, one taking a placebo and the other taking an experimental drug to prevent disease A. In the placebo group four developed the disease, while in the experimental group, three developed the disease. The baseline risk is 4%, and the ARR is 4% minus 3% that equates 1% (NNT = 1/0.01 = 100). The RRR is the ratio between the AAR of 1% and the baseline risk of 4%, matching 25%. The RRR is much larger than the ARR and may have a larger impact on the perception of the benefits. For the same number of individuals contracting the disease, the RRR would not change if there were a different number of individuals in each group. Let’s say that each group had 1000 individuals. The ARR would be much smaller, only 0.1% (NNT = 1000), but the RRR