Ch. 12 Epidemiology

Goals of Epidemiology

- Monitor the health of the population - Understand the determinants of health and disease in communities - Investigate and evaluate interventions to prevent disease and maintain health.

Epidemiologic concepts

Used to understand and explain how and why health illness occur as they do in human populations

Social Epidemiology

- A branch of epidemiology that studies the social distribution and social determinants of health and disease - Focus on the roles and mechanisms of specific social phenomena

Person characteristics

- Age, sex, ethnicity, race, education, occupation, income, marital status - Health habits and behaviors or lifestyle - Acquired resistance and susceptibility - Health history-natural resistance, hereditary characteristics

Analytic Epidemiology

- Answers questions about cause and effect(how and why) relationships between a potential risk factor and a specific health phenomenon or disease condition - Seeks to discover the factors that influence patterns of health and disease and increase or decrease the risk of adverse outcomes

Epidemiology

- Basic science of public health - The discipline that provides the structure for systematically studying the distribution and determinants of health, disease, and conditions related to health status.

Experimental Studies

- Carefully designed questions, hypotheses, and research protocols - Specific criteria for selection of the subjects to be studied - Method of random assignments to experimental and control groups

Environment Factors

- Climate - Socioeconomics - Working conditions - Plant and animal life - Population distribution

Epidemiology in Nursing Practice

- Collecting, reporting, analysis, interpretation and communication of epidemiological data as part of daily practice - Documentation on patient charts and records - Identify, report, treat, and provide follow-up on cases of illness

Descriptive Epidemiology

- Describes the amount and distribution of disease within a population - Person(who is affected) Place(where is the disease distributed in the human population) - Time(when is the disease present)

Prevalence importance

- Determining measures of chronic illness in a population and is affected by factors that influence the duration of the disease - Affects the planning for health care services, resources, and facilities, determining health care personnel needs, and for evaluating treatments that prolong life

Time Characteristics

- Frequency of disease over time - Cyclical patterns - Point epidemic - Clusters of events - Secular trends

Host Factors

- Genetics - Demographics (age, race, sex) - Lifestyle behaviors (smoking) - Immunity status (behind on vaccines) - Herd immunity- resistance of a group or community to invasion and spread of an infectious agent (Not vaccinating kids)

Place Characteristics

- Geographic variations in the chemical, physical, or biological environment - Religious, cultural, or ethnic groups who practice certain health-related behaviors - Neighborhood variables (zip code), unemployment, crime rate, access to important services

Screening is recommended for health problems that:

- Have a high prevalence - Relatively serious - Can be detected in early states - Effective treatment is available

Epidemiological Triangle

- Host - Agent - Environment

Host

- Human or animal capable of being infected by an agent - Person characteristics (age, race, sex)

Agent factors

- Infectious agents - Chemical agents - Physical agents

Agent

- Infectious, chemical or physical - Machinery injury, chronic illness - Virus, parasite, fungus or bacteria

Secular trends

- Long term patterns of morbidity and mortality rates (over years and decades) - May reflect changes in social behavior or health practices - Increasing number of cancer mortality rates among men and women in recent years reflect a delayed effect of increased smoking in prior years.

Requirements to conduct screenings

- Must have built in referral mechanisms for diagnostic evaluation for those who screen positive - Must have effective protocols in place for referral to accessible and appropriate follow-up care and treatment - The screening program must be assessed for ethical measures as well as epidemiologically

Cluster of events

- Patterns in which time is not measured from fixed dates on the calendar but from the point of some exposure or event, presumably experienced in common by affected persons, although not occurring at the same time. - Vaccine reactions in an ongoing immunization program

Nurse responsibility for screening

- Planning and implementing screening - Prevention programs targeted to the at-risk populations

Incidence influences

- Preventive health measures (flu vaccine) but unchanged by new medical treatment (medicine doesn't change the fact that you have the flu)

Cyclical patterns

- Seasonal fluctuation seen in the number of infectious illnesses - May be influenced by changes in the agent itself, changes in population densities, or behaviors of animal reservoirs or vectors, or changes in human behavior that result in changing exposures - Seasonal flu

Public health objective for screening

- Sort out effectively and efficiently those who probably have the disease from those who do not - Detect early cases for treatment or begin public health prevention and control programs

Screening

- Testing of groups of individuals who are at risk for a certain condition but not yet symptomatic - Early detection and treatment - Not a diagnosis (report what we see)

Community trials

- The issue is health promotion and disease prevention instead of treatment of an existing disease - Usually involves a large group of people - Collect data before and after - Some groups would get the health education and others would not

Passive surveillance

- The more common form used most by local and state health departments - Health care providers in the community report cases of notifiable diseases to the public health authorities through the use of standardization of reports - Inexpensive

Prevalence

- The number of existing cases of an illness or injury in a given point in time - New and existing cases - New and old cases are added together (prevalence number) Includes the new cases and existing cases

Incidence

- The number of new cases of an illness or injury in a population at risk that occurs within a specified time - Used for studying patterns of both acute and chronic illness - Provides a direct measure of the magnitude of new illness in a population

Active surveillance

- The purposeful, ongoing search for new cases of disease by public health personnel, through personal or telephone contacts, or the review of laboratory reports or hospital or clinical records - Costly

Clinical trials

- The research issue is generally the efficacy of a medical treatment for disease such as, a new drug or an existing drug used in a new or different way, a surgical technique, or another treatment - The preferred method of subject allocation is randomization to prevent bias

Point epidemic

- Time and space related pattern that's important in infectious disease investigations and is a significant indicator for toxic exposures in environmental epidemiology - Most clearly seen when the frequency of cases is plotted against time. - The sharp peak characteristic of such graphs indicates a concentration of cases in some short interval of time - Out break of GI illness from foodborne pathogens

Characteristics of a Successful Screening Program

- Valid(accurate) - Reliable(precise) - Capable of large group administration - Innocuous - High yield - Ethical and effective

The most important predictor of overall mortality

Age

Environment

All that is external to the host, including physical, biological, social, and cultural factors

School nurse epidemiology

Collect data on the incidence and prevalence of accidents, injuries, and illnesses in the school population

Florence Nightingale, the first nurse epidemiologist

Collected data, created a system of record keeping and graphic illustrations to show mortality rates and how improvements in sanitary conditions would lead to a decrease in deaths

Prevalence influences

How many people become ill and how many people recover or die

Surveillance

Involves the systemic collection, analysis, and interpretation of data related to the occurrence of disease and the health status of a given population

Social epidemiology examines:

Social inequalities and data related to neighborhoods, communities, employment, and family conditions to analyze health issues and to design appropriate and feasible public health interventions

Web of causality

The concept of a more complex interrelationship among the numerous factors interacting to increase or decrease disease

Natural history of disease

The course of the disease process from the onset to resolution.

Picking a population fro screening

The population should be easily identifiable and assessable, amenable to screening, willing and able to seek treatment or follow-up procedures (don't want to waist time)

Risk

The probability an event will occur within a specified time

Case fatality rate

The proportion of persons diagnosed with a particular disorder that die within a specified period of time

Attack rate

The proportion of persons who are exposed to an agent and develop the disease

Nursing use epidemiology concepts

To guide clinical practice and influence health outcomes