As well as seeking to improve population health through the implementation of specific populationlevel interventions public health contributes to medical care by identifying and assessing population needs ID: 933725
Download Presentation The PPT/PDF document "Applications of Public Health knowledge" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
Applications of Public Health knowledge
As
well as seeking to
improve population health
through the implementation of specific population-level interventions, public health contributes to
medical care
by identifying and assessing population needs
for health care services
,
including
Assessing
current services and
evaluating
whether they are meeting the objectives of
the healthcare system
Ascertaining requirements
as expressed
by health professionals,
the public and other stakeholders
Identifying the most appropriate
interventions
Considering the effect on resources for proposed interventions and assessing their
cost-effectiveness
Supporting decision making
in health care and planning health services including any necessary changes.
Informing, educating, and empowering people about health issues
Slide2Nutritional epidemiology
farooq@asab.nust.edu.pk
Slide3Epidemiology
Originally, the study of epidemics / outbreaks
Study of the factors that contribute to illness in individuals and communities, and how to improve health by altering those factors
Slide4Epidemiology
and
Public Health
Slide5DEFINITIONS
What is epidemiology?
What is an epidemiologist?
Slide6How we view the world…..
Pessimist: The glass is half empty.
Optimist: The glass is half full.
Epidemiologist: As compared to what?
Slide7EPIDEMIOLOGY is the study of the nature, cause, control and determinants of the frequency and distribution of disease, disability, and death in human populations.
Epidemiology: the study of factors influencing the
occurrence,
transmission, distribution, prevention and control of disease in a defined population
What is epidemiology?
Slide8“The study of skin diseases?
”
“The study of epidemics?”
“The study of the distribution and determinants of health-related states in specified populations, and the application of this study to control health problems."
What is epidemiology?
Slide9epidemiologists
study sick and healthy people
to determine the crucial difference between those who get the disease and those who are spared
epidemiologists
study exposed and non-exposed people
to determine the crucial effect of the exposure
EPIDEMIOLOGY is the study of the nature, cause, control and determinants of the frequency and distribution of disease, disability, and death in human populations.
What is epidemiology?
Slide10An EPIDEMIOLOGIST
is a public health scientist, who is responsible for carrying out all useful and effective activities needed for successful epidemiology
practice
Disease-detective
Slide11Uses of Epidemiology..
Slide12Uses of Epidemiology..
Slide13Slide14Terminology
Endemic
Hyperendemic
Holoendemic
Epidemic/outbreak
Pandemic
Epizootic
Incidence
Prevalence
Terms used for reference
to various forms of
outbreaks
Slide15Endemic: a disease or pathogen present or usually
prevalent
in a given population or geographic region at all
times
Hyperendemic
: equally
endemic
in all age groups of a
population
Holoendemic
:
endemic
in most of the children in a population, with the adults in the same population being less often
affected
Epidemic: a disease
occuring
suddenly in numbers far exceeding those attributable to
endemic
disease;
occurring
suddenly in numbers clearly in
excess
of normal
expectancy
Pandemic: a widespread epidemic distributed or
occurring
widely throughout a region, country, continent, or
globally
Epizootic: of, or related to a rapidly spreading and widely diffused disease affecting large numbers of animals in a given region
Incidence: rate of occurrence of an event; number of new cases of disease
occurring
over a specified period of time; may be expressed per a known population
size
Prevalence: number of cases of
disease
occurring within a population at any one given point in time
Slide16What is an Outbreak?
An outbreak is the occurrence of more cases of a disease than expected in a population during a certain time
One case of smallpox, anthrax, plague, botulism, or tuberculosis anywhere in the US is an outbreak requiring immediate response
An epidemic and an outbreak mean the same thing
Epidemic is often applied to an outbreak of special concern
Slide17How Are Outbreaks Detected?
Recognized and reported by individual doctors or groups (e.g., an emergency
dept
)
Recognized and reported by those affected (e.g., coworkers, school, banquet)
Detected by PH agency through review of individual cases reported by doctors, or review of lab reports or other health care data
Enhanced surveillance in cooperation with state and federal public health officials
Slide18Methods of Epidemiology
Public Health Surveillance
Disease Investigation
Analytic Studies
Program Evaluation
Slide19Surveillance
The ongoing, systematic collection, analysis, and interpretation of health data essential to the planning, implementation, and evaluation of public health practice, closely integrated with the timely feedback of these data to those who need to know.
In public health, ‘surveillance’ means tracking the occurrence of diseases of importance – not watching individuals or premises
Slide20Analytical studies
Observational:
Case-Control:
Exposures, genes, and/or behaviors in individuals with a particular disease (cases) are compared to individuals without the disease (controls).
Cohort:
A group of individuals with and without a particular exposure are followed to compare disease outcomes.
Interventional:
Clinical Trials:
Individuals are randomized to receive a particular treatment within the clinic setting.
Community Trials:
A community participates in a behavioral intervention, a screening intervention, etc.
Slide21Study Design:
Population-Based:
Individuals under study belong to a defined population, i.e., residents of a geographic region.
Clinic or Hospital-Based:
Studies are based upon patients seen at a particular hospital or clinic.
Community-Based:
Participants are volunteers in the community.
Analytical studies
Slide22Behavior, Genetics, Environment, Social/Cultural Risk Factors
Health
Pre-
cancer
Cancer
Recurrence
Etiologic studies
Genetic
Molecular
Environmental
Social/Cultural
Behavioral Interventions
Screening
Chemoprevention Trials
Quality of life
Predictors of survival
Chemoprevention Trials
Survivorship
Risk Assessment,
Primary Prevention
Early Detection,
Secondary Prevention
Tertiary Prevention
All studies conducted in a population that is racially and ethnically diverse
Analytical studies
Slide23Surveillance Epidemiology and End Results (SEER) Program
Assemble and report estimates of cancer incidence and mortality in the United States.
Monitor annual cancer incidence trends.
Provide continuing information on changes over time
in extent of disease at diagnosis, trends in therapy, and associated changes in patient survival.
Promote studies designed to identify factors amenable to cancer control interventions.
Population-Based Cancer Epidemiology
Slide24Cancer In Arab Americans: Estimating Rates & Fostering Research
Schwartz K, N01 PC35154-RRSS
Arab/Chaldean men had greater proportions of leukemia , multiple myeloma, liver, kidney, and urinary bladder cancers.
Arab/Chaldean women had
greater proportions of leukemia, thyroid, and brain cancers.
Arab–American women have similar distribution of
breast cancer histology to European–American
women.
Arab–American stage, age, and hormone receptor status at diagnosis was more similar to African–American women.
Arab–American women have a better overall survival than even European–American women.
Slide25Jemal
et. al., 2010
Slide26Trends in lung cancer mortality rates by sex in select countries,
1950-2006
Jemal
et. al., 2010
Slide27Kinds of Epidemiology
Descriptive
Analytic
Experimental
Further studies to determine the validity of a hypothesis concerning the occurrence of disease.
Deliberate manipulation of the cause is predictably followed by an alteration in the effect not due to chance
Study of the occurrence and distribution of disease
Slide28Overview of epidemiologic design strategies
Descriptive
Populations{Correlational studies}
Individual
Case report
Case series
Cross sectional studies
Analytic studies
Observational
Case control
Cohort
Retrospective
Prospective
Interventional/Experimental
Randomized controlled trial
Field trial
Clinical trial
Slide29Descriptive vs. Analytic Epidemiology
Descriptive
Used when little is known about the disease
Rely on preexisting data
Who, where, when
Illustrates potential associations
Analytic
Used when insight about various aspects of disease is available
Rely on development of new data
Why
Evaluates the causality of associations
Both are important!
Slide30Descriptive Studies
Relatively inexpensive and less time-consuming than analytic studies, they describe,
Patterns of disease occurrence, in terms of,
Who gets sick and/or who does not
Where rates are highest and lowest
Temporal patterns of disease
Data provided are useful for,
Public health administrators (for allocation of resources)
Epidemiologists (first step in risk factor determination)
Slide31Descriptive Epidemiology
Correlational studies
Case reports
Case series
Cross sectional studies
Slide32Correlational Studies (Ecological Studies)
Uses measures that represent characteristics of entire populations
It describes outcomes in relation to age, time, utilization of services, or exposures
ADVANTAGES
We can generate hypotheses for case-control studies and environmental studies
We can target high-risk populations, time-periods, or geographic regions for future studies
Slide33Correlational Studies
LIMITATIONS
Because data are for groups, we cannot link disease and exposure in individual
We cannot control for potential confounders
Data represent average exposures rather than individual exposures, so we cannot determine a dose-response relationship
Caution must be taken to avoid drawing inappropriate conclusions, or ecological fallacy
Slide34Case Reports (case series)
Report of a single individual or a group of individuals with the same diagnosis
Advantages
We can aggregate cases from disparate sources to generate hypotheses and describe new syndromes
Example: hepatitis, AIDS
Limitations
We cannot test for statistical association because there is no relevant comparison group
Based on individual exposure {may simply be coincidental}
Slide35Case report/Case series(contd.)
Important
interface
between clinical medicine & epidemiology
Most common type of studies published in medical journals{1/3
rd
of all}
AIDS ~ b/w oct1980-may81, 5 cases of
P.carinii
pneumonia were diagnosed among previously healthy young homosexual males in L.A.
Slide36Cross-Sectional Studies (prevalence studies)
Measures disease and exposure simultaneously in a well-defined population
Advantages
They cut across the general population, not simply those seeking medical care
Good for identifying prevalence of common outcomes, such as arthritis, blood pressure or allergies
Limitations
Cannot determine whether exposure preceded disease
It considers prevalent rather than incident cases, results will be influenced by survival factors
Remember: P = I x D
Slide37Cross-Sectional Studies
Can be used as a type of analytic study for testing hypothesis, when;
Current values of exposure variables are unalterable over time
Represents value present at initiation of disease
E.g. eye colour or blood group
If risk factor is subject to alterations by disease, only hypothesis formulation can be done
Slide38The epidemiologic approach:
Steps to public health action
MEASURES
Counts
Times
Rates
Risks/Odds
Prevalence
METHODS
Design
Conduct
Analysis
Interpretation
ALTERNATIVE
EXPLANATIONS
Chance
Bias
Confounding
INFERENCES
Epidemiologic
Causal
ACTION
Behavioural
Clinical
Community
Environmental
DESCRIPTIVE
What (case definition)
Who (person)
Where (place)
When (time)
How many (measures)
ANALYTIC
Why (Causes)
How (Causes)
Slide39Descriptive Epidemiology
Study of the occurrence and distribution of disease
Terms:
Time
Place
Person
Slide40What are the three categories of descriptive epidemiologic clues?
□
Person:
Who is getting sick?
□
Place:
Where is the sickness occurring?
□
Time:
When is the sickness occurring?
PPT = person, place, time
Slide41Time
Secular
Periodic
Seasonal
Epidemic
Slide42Secular Trend
The long-time trend of disease occurrence
Slide43Tetanus – by year, USA, 1955-2000
During 2000, a total of 35 cases of tetanus were reported. The percentage of cases among persons aged 25-59
years has
increased in the last decade. Note: A tetanus vaccine was first available in 1933.
Slide44Possible Reasons for Changes in Trends
Artifactual
Errors in numerator due to
Changes in the recognition of disease
Changes in the rules and procedures for classification of causes of death
Changes in the classification code of causes of death
Changes in accuracy of reporting age at death
Errors in the denominator due to error in the enumeration of the population
Slide45Possible Reasons for Changes in Trends (cont.)
Real
Changes in age distribution of the population
Changes in survivorship
Changes in incidence of disease resulting from
Genetic factors
Environmental factors
Slide46Other phrases
Cyclic trends
~ recurrent alterations in occurrence , interval or frequency of disease
Secular cyclicity
Levels of immunizations
Build up of susceptibles
e.g. Hep A-7 yr cycle,Measles-2yr cycle
Short term cyclicity
Chickenpox,salmonella(yearly basis)
Slide47Periodic Trend
Temporal interruption of the general trend of secular variation
Slide48Whooping Cough - Four-monthly admissions, 1954-1973
Slide49Seasonal
A cyclic variation in disease frequency by time of year & season.
Seasonal fluctuations in,
Environmental factors
Occupational activities
Recreational activities
Seasonal affective disorder
Slide50Seasonal Trend
Pneumonia-Influenza Deaths – By year, 1934-1980
Slide51Slide52Person
Age Hobbies
Sex Pets
Occupation Travel
Immunization status Personal Habits
Underlying disease Stress
Medication Family unit
Nutritional status School
Socioeconomic factors Genetics
Crowding Religion
Slide53Host.....
Personal traits
Behaviours
Genetic predisposition
Immunologic factor
Agent.....
Influence the chance for disease or its severity
Biological
Physical
Chemical
Environment.....
Contribute to the disease process
External conditions
Physical/biological/social
Slide54due to new agent.
due to change in existing agent (infectivity, pathogenicity, virulence).
due to change in number of susceptibles in the population
due to environmental changes that affect transmission
of the agent or growth of the agent.
Epidemics Occur when.......
host, agent and environmental factors are not in balance
Slide55INTRODUCTION to NE
Incomplete understanding of biologic mechanisms
Inability to predict consequences of a food or nutrient.
To understand the relationship between diet and long term health and disease
Thus, the epidemiologic studies directly relating intake of dietary components to risk of death or disease among humans play a critical complementary role to laboratory investigation.
Slide56What is Nutritional epidemiology
?
Concept: diet influences occurrence of diseases
Relatively new: the basic method used for > 200 years to identify essential nutrients
Nutritional epidemiology is a relatively new discipline which combines the knowledge compiled by nutritionists during this century with the methodology developed by epidemiologists to study the determinants of diseases with multiple etiologies and long latent periods.
【Example】 Observations that fresh fruits and
vegetables could cure scurvy by Lind in 1753.
Slide57Nutritional epidemiology
Epidemiology is the study of the occurrence of human diseases. Nutritional epidemiology focuses on the relationship between our diet and our health.
Slide58History
Scurvy
Lind 1753
Beriberi
Kanehiro
Takaki in 1884
Rickets, pellagra
Casimir
Funk 1912
Niacin (
vit
B3 deficiency)
Dr.Joseph
Goldberger 1915
Conrad
Elvehjem
1938
Slide59Itai-itai
disease
"ouch ouch
sickness”,
was the documented case of mass
cadmium poisoning in Toyama Prefecture
,
Japan
. The
cadmium
poisoning
kidney
failure. The disease is named
for
caused
softening of the bones
and
the severe pains (Japanese:
痛い
itai
) caused in the joints and spine. The term
itai-itai
disease was coined by locals
.
The
cadmium was released into rivers by
mining
companies in the mountains. The mining companies were successfully sued for the damage
.
History
Slide60Goals of nutritional epidemiology
Monitoring the food consumption, nutrient intake and nutritional status of a population.
G
enerate new hypotheses about diet and disease, to produce evidence that supports or refutes existing hypotheses and to assess the strength of diet-disease associations.
Contribute to the prevention of disease and improvement of public health
Slide61Understanding the complex relationships between diet and the major diseases (as cancer and atherosclerosis)
Having an overview of research strategies in nutritional epidemiology
Identifying methods of dietary assessment using data on food intake, biochemical indicators of diet, and measures of body size and composition.
Discussing the analysis, presentation, and interpretation of data from epidemiologic studies of diet
Goals of nutritional epidemiology
Slide62Advantages of Nutritional Epidemiology
Direct relevance to human health.
The epidemiological results are used to calculate direct estimates of risk, which can then be translated into specific recommendations for changes in nutrient intakes or food consumption patterns.
Findings from nutritional epidemiology can even have direct implications for food processing and technology
Slide63High intakes of trans fatty acids (found in margarine and other processed vegetable fats) with increased risks of coronary heart disease
Example
Slide64The most important one is the potential for many kinds of bias.
Bias is defined as systematic error, resulting in over- or underestimation of the strength of an association between an exposure and an outcome.
Studies in nutritional epidemiology must be designed and executed with great care to minimize bias.
Difficulties
Slide65The difficulty in determining whether observed associations are causal. If the association between a factor and a disease is not
causal
, efforts to modify exposure to that factor will not reduce disease risk.
Alcohol & lung cancer
Slide66The apparent simplicity and
“
real life
”
rel
evance of epidemiological findings
encourage misuse & over-interpretation of data when preliminary or unconfirmed findings come to the attention of the news media and the general public.
For example
, the reports of an association between margarine intake and cardiovascular disease may have prompted some consumers to switch back to butter, even though most experts believe that this course of action would not be beneficial to cardiovascular health.
Slide67Nutrition problems in the past
Typical deficiency syndromes
Protein energy malnutrition
Iron deficiency anemia
Goiter
High frequency among those with very low intake
Short latent periods
Can be reversed within days or weeks
Slide68Contemporary nutritional epidemiology
Major diseases throughout the world
Heart disease
Cancer
Osteoporosis
Cataracts
Stroke
Diabetes
Congenital malformations
Slide69Characteristics
Multiple determinants (causes)
diet, genetic, occupational, psychosocial, and infectious factors; levels of physical activity; behavioral characteristics
Long latent periods
cumulative exposure over many years, or relatively short exposure occurring many years before diagnosis
Occur with relatively low frequency
despite a substantial cumulative lifetime risk
Conditions not readily reversible
May result from excessive and/or insufficient intake of dietary factors
Why is it hard to study contemporary nutrition-related disease?
Slide70C
oronary heart disease
Slide71The complex nature of diet has posed an unusually difficult challenge to nutritional epidemiology:
Diet represents an unusually complex set of exposures that are strongly
intercorrelated
,
cannot be characterized as present or absent
Continuous variables often with a rather limited range of variation
complex nature of
diet
Slide72Evolving patterns
Preparatory methods
Unawareness of nutrients
Estimates
Comparison with another factor
Slide73"Do you eat?”
Vs.
“Do you smoke?”
Slide74Limitation in nutritional epidemiology research:
-
Lack of practical methods
to measure diet for large number of subjects
-
Dietary assessment methods must be:
Reasonably accurate
Relatively inexpensive
-Diets of persons within one country are too homogeneous
to detect relationships with disease.
Slide75Epidemiologic Approaches
to Diet and Disease
Sources of the concepts, hypotheses, and techniques
of nutritional epidemiology:
-
Biochemistry
-Cell culture methods
-Experiments in laboratory animals
-Metabolic and biochemical studies among human subjects
Findings from in vitro studies and animal experiments
cannot be extrapolated
directly to humans
The basic science areas provide
critical direction
for information that can aid in the interpretation of the epidemiologic findings:
New methods for measuring genetic and environmental exposures that can be applied in epidemiologic studies
Slide76Who is an epidemiologist?
Many disciplines:
Doctors (MD, DO, DVM, PhD)
Nurses (RN, PHN)
Laboratory workers (microbiologists, technologists)
Social workers, health educators
Environmental health workers
Attorneys
Administrators
Many have additional degrees/training in public health
Slide77Goal of Epidemiologic Investigation: Prevention
This is the source of urgency for PH staff
Find and fix ongoing point source (like contaminated water supply)
Close location until fixed
Take food product off the market
Find, isolate, and treat infectious people
Find exposed people, give them prophylactic treatment or vaccine, and/or quarantine them
Slide78Steps in an Outbreak Investigation
Detect problem by public health surveillance
Verify diagnosis
Confirm outbreak
Identify / count cases
Characterize data ® time / place / person
Take immediate control measures
Formulate / test hypotheses
Implement / evaluate additional control measures
Report findings
Slide79Public Health Emergencies
Threat and reality of bioterrorism have focused attention on public health preparedness for emergencies
Planning for public health emergencies requires interagency agreements, training, and exercises
Slide80Public Health Emergencies
Examples of public health emergencies:
Natural disaster: hurricanes, floods, earthquakes;
Outbreaks from contaminated food or water, influenza pandemics;
Biological, chemical, radiological and nuclear WMD
Slide81What Should Make You Suspect an Intentional Outbreak?
Cases of an extremely rare disease (anthrax, plague, smallpox) that could be BT agent
Ordinary disease but out of season or area or with wrong mode of spread or other unusual characteristics (I.e. antibiotic resistance, atypical symptoms or victim demographics)
Cannot solve outbreak with usual techniques
Threats received
Group taking credit
Plausible accusations
Slide82What Should Make You Suspect an Intentional Outbreak?
All victims attended a common event
All victims share a common workplace or other locale
All victims work for the same agency
A dissemination device is found
Whom should PH workers call first in this community when they receive allegations that someone has caused an outbreak deliberately?
Slide83Categories of Intervention
Efforts directed at source of infectious agent
Vehicle
Vector
Efforts directed at people at risk
Slide84Poultry “Biosecurity”
USDA guidance to prevent
introduction/spread of A.I.
Slide85Interventions Directed at Source
Eliminate / treat source
Dispose of contaminated food, shock-chlorinate contaminated water
Isolate / treat infected persons
Prevent further exposures by minimizing susceptible’ risk of exposure to infectious persons
Close contaminated sites / sources
Protect susceptible by minimizing risk of exposure from infected sites / sources
Slide86Interventions Directed at People at Risk
Reduce risk of exposure in susceptible people – e.g., by educating on how to avoid exposure
Directly protect at-risk people
Vaccinate
Post-exposure treatment with medicines or vaccines to prevent or lessen illness
Slide87Slide88