Epidemiology

Introduction

Epidemiology is the study and analysis of the distribution, patterns and determinants of health and disease conditions in defined populations. It is a cornerstone of public health, and informs policy decisions and evidence-based practice by identifying risk factors for disease and targets for preventive healthcare. Epidemiologists help with study design, collection, and statistical analysis of data, interpretation, and dissemination of results (including peer review and occasional systematic review).1(https://www.ncbi.nlm.nih.gov/books/NBK459031/)

A group of epidemiologists studying data on a large screen.

History

The development of epidemiology has been a gradual process that evolved over centuries. The term 'epidemiology' was first used in the English language in the 1800s, but its roots can be traced back to ancient times. The earliest recorded thoughts towards epidemiology were the observations of Hippocrates in the era 460 B.C - 370 B.C. Hippocrates attempted to explain disease occurrence from a rational rather than a supernatural viewpoint. In doing so, he noted the environmental and host factors influencing health and disease.2(https://www.ncbi.nlm.nih.gov/books/NBK459031/)

A depiction of ancient epidemiologists studying disease patterns.

Branches of Epidemiology

Epidemiology is a diverse field and can be broken down into several branches, each with its own unique focus and methodologies. These include:

Descriptive Epidemiology

Descriptive epidemiology provides a way of organizing and analyzing data on health and disease in order to understand variations in disease frequency geographically and over time, and how disease varies among people based on a host of personal characteristics (person, place, and time).3(https://www.ncbi.nlm.nih.gov/books/NBK459216/)

Analytical Epidemiology

Analytical epidemiology seeks to investigate and understand the causes of disease by determining why a disease rate is lower in one population compared to another. It is concerned with the search for health-related causes and effects. It uses logic structures to understand the complex relationships between risk factors and disease.4(https://www.ncbi.nlm.nih.gov/books/NBK459216/)

Clinical Epidemiology

Clinical epidemiology is the application of epidemiological principles and methods to problems encountered in clinical medicine. It provides a quantitative approach to evidence-based medicine and patient care.5(https://www.ncbi.nlm.nih.gov/books/NBK459216/)

A clinical epidemiologist studying patient data.

Epidemiological Methods

Epidemiological methods are the techniques used by researchers to study health phenomena. These methods include:

Observational Studies

Observational studies observe individuals and measure variables of interest without assigning treatments to individuals. They can be either descriptive or analytical in nature.6(https://www.ncbi.nlm.nih.gov/books/NBK459216/)

Experimental Studies

Experimental studies are those in which the researcher manipulates exposure to a factor, assigns subjects randomly to conditions, and observes the onset and course of health events.7(https://www.ncbi.nlm.nih.gov/books/NBK459216/)

Cohort Studies

Cohort studies are observational studies that follow a group of individuals (a cohort) over time, measuring their exposure to certain risk factors and tracking the occurrence of health outcomes.8(https://www.ncbi.nlm.nih.gov/books/NBK459216/)

A team of researchers conducting a cohort study.

Applications of Epidemiology

Epidemiology is applied in many areas of public health and is critical in disease prevention and health promotion. Some of the key applications include:

Disease Surveillance

Disease surveillance is an epidemiological practice by which the spread of disease is monitored to establish patterns of progression. The main role of disease surveillance is to predict, observe, and minimize the harm caused by outbreak, epidemic, and pandemic situations, as well as increase knowledge about which factors contribute to such circumstances.9(https://www.ncbi.nlm.nih.gov/books/NBK459216/)

Outbreak Investigation

Outbreak investigation involves the identification of a suspected outbreak, confirmation of the outbreak, establishment of a case definition, and identification of additional cases. It also involves describing the outbreak in terms of person, place, and time, and identifying and testing the hypothesis about the cause of the outbreak.10(https://www.ncbi.nlm.nih.gov/books/NBK459216/)

Screening

Screening is the process of identifying healthy people who may be at increased risk of a disease or condition. They can then be offered information, further tests and appropriate treatment to reduce their risk and/or any complications arising from the disease or condition.11(https://www.ncbi.nlm.nih.gov/books/NBK459216/)

Future of Epidemiology

The future of epidemiology will be shaped by many factors, including advances in technology, changes in health care systems, and shifts in health policy. The increasing availability of big data and the development of new analytical methods will likely play a significant role in shaping the future of the field.12(https://www.ncbi.nlm.nih.gov/books/NBK459216/)

References