University:
American Baptist College
Course:
IKM 20632 | Basic Epidemiology
Academic year:

2023
Views:

442

Pages:

3
Author:

Muthia M

Frequency Measures in Epidemiology A. Definition of Epidemiology An expert named Last (1988) argues that epidemiology is the study of the distribution and determinants of health-related circumstances or events in a given population, and the application of these studies to control health problems. B. Epidemiologic Distribution Epidemiology is concerned with the frequency and patterns of health events in a population. C. Measures of Disease 1. Quantification of disease incidence 2. Count infected, sick and deceased individuals 3. Use words a. Usually, sometimes, rarely. b. Little agreement on the general meaning of the words used for frequency 1) "usually" = 0.5 - 0.8 2) "Occasionally" = 0,2 - 0,6 3) "rarely" = 0.01 - 0.2 4. Mathematical quantity type 5. Type of measure used in epidemiology D. Measures of Frequency of Disease Occurrence Broadly speaking, the incidence of disease can be: 1. Morbidity / sickness 2. Mortality / death There are 3 kinds of mathematical parameters used to describe the relationship between the number of disease events and the size of the population from which disease events occur. These parameters are: 1. Ratio 2. Proportion 3. Rate E. Mathematical Quantity Type 1. Enumeration (count) 2. Ratio 3. Proportion 4. Rate F. Types of Measures Used in Epidemiology 1. Measures of disease frequency 2. Association measures 3. Impact measures G. Mathematical Quantity Type 1. Counts (enumerations) or absolute numbers a. Gross number or frequency b. Example: 10 cases, 1961 cases 2. Counts a. The most basic and commonly used measure in epidemiology. b. Incidence refers to the number of occurrences of a disease or other health phenomenon under investigation, such as the number of influenza cases in Allegheny County in January 2002. Total count of individuals who have been involuntarily referred for psychiatric crisis intervention c. Beneficial for the allocation of healthcare resources d. The data's epidemiological value is limited without knowledge of the source population's size. 3. Ratio A ratio is the value obtained by dividing one quantity by another. A ratio is a quantity where the numerator may differ from the denominator or the denominator may not contain the numerator. 4. Proportion A proportion is a fraction or type of ratio in which the numerator is a part of the denominator that, when multiplied by 100, is usually called a percentage. For Example: 28/56 = 0,5; 0,5 x 100% = 50%. There are 28 cases out of 56 people. This means the proportion of cases is 50%. 5. Rate A specific type of ratio used to quantify dynamic processes such as growth and velocity. A numerical expression of the frequency of an event calculated by dividing between the number of individuals who experience the event (numerator) and the total number of individuals who could possibly (capably) experience the event (denominator or population at risk) and multiplied by a constant. Rate also can mean a numerical statement of the frequency of events occurring in a given group of people defined over a period of time