1.1 Reading Assignment:

Chapters 1 & 3 - Textbook (Martin et al.)

Chapters 1 & 2 - Textbook (Schwabe et al.)

Chapters 1 & 2 - Susser M.: Casual Thinking in the Health Sciences.

Lecture Notes - Chapter 1

1.2 Introduction to Epidemiology 

1.2.1 Objectives:

• 1) To understand the basic concepts of epidemiology
• 2) To define important epidemiologic terminologies
• 3) To examine how epidemiologic concepts are used to study population health problems

 

 

Problem Definition: What is Epidemiology?

 

 1.2.2 Basic Concepts and Principles:

1.2.2.1 Definition:

Epidemiology is the branch of science that deals with the study of the dynamics of health and ill health in populations.

1.2.2.2 Important epidemiologic concepts:

• - The health/ill health continuum in a population
• - population dynamics
• - multiple causality and multiple determinants

 In the definition of epidemiology, reference is made to "population". This aspect is a distinct epidemiologic entity in that epidemiology per se is not concerned with an individual animal or human as such, but in terms of what happens to the population; including the healthy and unhealthy ones. It is only then that one could understand and unravel patterns and frequencies of events in order to proceed with further corrective actions and appropriate followups.

The study of epidemiology is therefore inherently population based in comparison to such fields as clinical medicine where the individual is the unit of concern. The components of the population include the various stages of health/ill health as given above. Additionally, although the thrust is one of population medicine, this by no means restricts the study to groups (herds, kennels, communities, etc.), of animals, humans or etiological agents; the same population concepts apply even at the cellular and molecular level.

The emergence of specialities such as Molecular Epidemiology, Cellular Epidemiology and even Anatomic Epidemiology to name just a few of over a dozen sub-specialities is therefore understandable. Epidemiology as a discipline deals with the study of populations from the level of the ecosystems of the cell to that of animals and humans. The classical area of the zoonoses falls in this domain. 

1.2.2.3 The Problem Oriented Epidemiologic Approach:

It consists of two major steps. These are:

• 1. Problem Identification and Definition
• 2. Problem Solution or Management

  1.2.2.3.1 Problem Identification and Definition:

  in Biomedicine in general and Epidemiology in particular, the first problem-solving step classically leads to the what is referred to as DIAGNOSIS.

  Note: that this also is the first decision-making step in medicine.

  1.2.2.3.2 Problem Solution or Problem Management:

  once a problem has been identified and well understood, the next step is to solve the problem. This general area is referred to as Problem Management since quite often the problem has to be managed (it may not be easily resolved).

  Clearly, the eventual goal of epidemiologic efforts is to PREVENT or CONTROL diseases and unhealthy or unsafe conditions in populations of humans or animals. 

1.2.3 Goals in Epidemiology

Epidemiology is conceptually goal oriented and purposeful. As such, it focuses on three distinct objectives, viz. therapeutic, preventive, health maintenance and promotion.

• 1. maintenance and promotion of the healthy state.
• 2. preventive action - to inhibit the transition from healthy to the unhealthy state by avoiding and/or minimizing exposure to risk factors.
• 3. Curative (therapeutic) - increasing recoveries from unhealthy to the healthy state and thus minimizing mortalities.

1.2.4 Uses of Epidemiology:

1.2.4.1 Serves as a diagnostic discipline

• A.1. Intensive Follow-Up
• A. 2. Surveillance

1.2.4.2 Directed action against diseases

It can be stated then that the eventual goal of epidemiologic efforts is to PREVENT or CONTROL diseases and unhealthy or unsafe conditions in populations of humans or animals.