Introduction

This textbook is intended as a primer and reference for students in medical school taking an epidemiology course, preparing for the USMLE Step 1 Exam, or needing to refresh on epidemiologic concepts. Medical school students in the United States must have a basic grasp of epidemiology and how it is used in population health and clinical medicine to continue past the first year of medical school. This textbook is designed for these students and contains information that can support students as they progress in their clinical career. The goal of this textbook is to provide students with the basics of epidemiology terms and concepts.

This textbook begins with an introduction to general concepts of epidemiology, including the definition of the field, basic terms such as incidence and prevalence, and descriptions of the ways information can be counted. It progresses to how measurements and calculations in epidemiology are applied to different study designs, why one might choose a particular study design to answer a clinical question, and detailed use of measures of association and effect in different study designs. After demonstrating how epidemiology is used in clinical diagnosis and screening of disease, the textbook ends with an overview and examples of sources of error in epidemiologic studies, including bias, confounding, and effect modification.

This textbook is meant for clinical students without backgrounds in public health, particularly those who are seeking a medical degree. Ideally, students in any clinical field, including nursing and physical therapy, can use this text as a reference for epidemiologic concepts that surface while taking care of patients or learning about different conditions. This book specifically will guide medical school students as they prepare for the USMLE Step 1 Exam and to transition from student to clinician.

The author chose to write this text while teaching medical school students epidemiology. The author noticed a large gap between the detail public health students needed to know (and subsequently what most textbooks focused on) and what medical school students needed to know. No other book explained the concepts at a level simple enough to be truly introductory and appropriate for a medical school audience. This matters because these two groups of students will work together throughout their careers, but the group of medical school students have a different reason to need to know this information and how it should be used. A textbook to approach their needs was necessary.

This textbook is heavily driven by practical examples, the majority of which are sports-related. It is an open access and openly licensed textbook available digitally at no cost and features accessible text and graphics.

Parts of This Book

• Chapter 1, Epidemiology in Sum, explains the overarching idea of epidemiology.
• Chapter 2, Measuring Things in Epidemiology, explains how things are counted and the dynamics of disease.
• Chapter 3, Study Designs, includes study designs and related measures.
• Chapter 4, Diagnostics and Screening, covers the use of epidemiology in disease diagnosis and screening.
• Chapter 5, The Wrecking Ball, examines bias, confounding, interaction and effect modification, including what they are and how to work with them.
• Appendix, Study Guides, includes handwritten visual summaries of chapters 2, 3, and 4.

What Content in This Text Is Relevant to the USMLE Step 1 Exam?

The following table shows which chapters in this text are in alignment with the First Aid for the USMLE Step 1 book (2022 edition): L. Tao, B. Vikas, and S. Matthew, First Aid for the USMLE Step 1 2022, 32nd ed., McGraw Hill LLC, 2022.