Explanation of the term community epidemiology

Epidemiology: It is the science that studies the distribution of diseases and health states among the population and their influencing factors, and studies strategies and measures to prevent and treat diseases and promote health.

Chapter 2 Distribution of Disease

Distribution of disease: refers to the frequency and distribution of diseases in different groups of people (human world), different regions (space), and different times (time) , is the starting point and foundation of epidemiological research.

Ratio: Also called relative ratio, it represents the value obtained by dividing two numbers to illustrate the relative level of the two.

Proportion: illustrates a certain The proportion or distribution of each component within a thing

Rate (rate): It represents the ratio of the actual number of instances of a certain phenomenon to the total number of possible instances of the phenomenon under certain conditions. To describe the frequency or intensity of a phenomenon occurring per unit time.

Incidence indicators

1) Incidence rate: refers to the frequency of new cases of a certain disease among a specific population within a certain period of time. Purpose: Used to describe the distribution of diseases, explore disease factors, propose etiological hypotheses and evaluate the effectiveness of imitation measures

2) Attack rate (attack rate): a frequency indicator that measures the frequency of new cases. Similar to the incidence rate, the numerator is the number of new cases. The difference is that the attack rate measures the frequency of new cases in a small area and within a short period of time.

3) Prevalence rate: refers to the proportion of new and old cases of a certain disease among a certain population within a specific period of time. Prevalence = incidence rate * disease duration.

4) Infection rate: refers to the proportion of people currently infected with a certain disease among the population samples examined at a certain time.

5) Disability rate (disability rate): refers to the frequency of occurrence of disabled people in a certain group of people within a certain period of time.

Death indicators

1) Mortality rate: refers to the proportion of the number of people who died from all causes in a certain group of people within a certain period of time. It is the most commonly used indicator to measure the risk of death in a population.

2) Fatality rate: represents the proportion of deaths due to a disease among all patients suffering from the disease within a certain period of time. It is mostly used for acute diseases with short duration.

3) Survival rate: refers to the proportion of cases under observation that are still alive at the end of follow-up after n years of follow-up for people suffering from a certain disease. Often used to evaluate the long-term efficacy of certain chronic diseases.

4) Death rate: the mortality rate calculated according to different types of diseases, gender, age, occupation and other characteristics

The epidemic intensity of the disease

1) Sporadic refers to the general incidence rate of a certain disease among the population in a certain area over the years. Cases occur scatteredly or sporadically among the population, and there is no obvious connection between the cases. Used to describe the prevalence of a disease in a larger population.

2) Outbreak refers to the sudden occurrence of many patients with similar clinical symptoms in a short period of time in a local area or collective unit.

3) Epidemic means that the incidence rate of a certain disease in a certain area and at a certain time significantly exceeds the sporadic incidence level of the disease in the past year.

Regional agglomeration: The frequency of illness or death in a certain area is significantly higher than that in surrounding areas

Endemic diseases: relatively stable and frequent occurrences in one place or group of people, without the need for Diseases imported from other places

Migrant epidemiology (migrant epidemiology): It analyzes the differences in the incidence or mortality of a certain disease among the immigrant population, the local population in the place of immigration, and the population in the original place of residence. The occurrence is related to the influence of genetic factors or environmental factors.

Chapter 4 Descriptive Research

Descriptive study refers to the use of existing information or specially investigated information, including laboratory test results, according to different times and A method of grouping the characteristics of places or groups of people (three distributions) to truly describe the distribution of diseases or health conditions.

Prevalence survey (prevalence survey), also known as cross-sectional study, is a survey and research on the disease or health status and related factors of a specific group of people at a specific time point or period to describe its distribution and Descriptive epidemiological investigation method of correlation of relevant factors

1) Census: refers to the survey of all people in a specific range within a specific period of time in order to understand the prevalence of a disease or health status. Observe objects for investigation or examination. 2) Sampling survey refers to a survey method that extracts a certain number of observation object samples from all observation objects (population) determined by the research for investigation and analysis, and infers the overall characteristics based on the sample information.

Simple random sampling (simple random sampling): the simplest and most basic sampling method.

First, all observation objects are numbered one by one, and then a certain number of observation objects are selected to form a sample using a random number table or lottery.

Systematic sampling (mechanical sampling): First divide all observation objects into n identical parts in a certain order, and then randomly select the k-th observation object from the first part, and use this to equal intervals, from now on. An observation unit is selected from each part to form a sample. That is, a sampling method that mechanically selects units every few units in a certain order.

Stratified sampling: The overall unit is divided into several sub-levels (layers) according to certain characteristics, and then a sample is formed by purely random sampling from each layer.

Cluster sampling: Divide the population into several groups, and select some of the groups as observation units to form samples

Multi-stage sampling (multi-stage sampling): Carry out the sampling process in stages , the sampling methods used at each stage are often different, that is, a combination of the above sampling methods is commonly used in large-scale epidemiological surveys.