EPIDEMIOLOGY EPIDEMIOLOGY

By :By :

dr. Siswanto, M.Sc.dr. Siswanto, M.Sc.

INTRODUCTION OF INTRODUCTION OF EPIDEMIOLOGYEPIDEMIOLOGY

Why does a disease develop Why does a disease develop in some people and not in in some people and not in others ?others ?

The disease and health The disease and health problems are not randomly problems are not randomly distributed in a population. distributed in a population.

DEFINITIONDEFINITION

The study of the distribution and determinants of The study of the distribution and determinants of health related states or events health related states or events in specified in specified populations, and the application of this to the populations, and the application of this to the control of health problems.control of health problems.

The study of the distribution and change in The study of the distribution and change in diseases.diseases.

The study of the distribution and determinants of The study of the distribution and determinants of disease in human population disease in human population

“Study of disease and other health related phenomena in

group of persons. (Kramer MS, 1988)

A science concerned with describing the pattern of disease occurrence in

population and determining the factors which influence disease prevalence

and distribution with the ultimate objective of providing the basis of control

and prevention

The characterization of the distribution of The characterization of the distribution of health-related statehealth-related state or or eventsevents is one broad is one broad aspect of epidemiology called aspect of epidemiology called descriptive descriptive epidemiology.epidemiology.

Epidemiology is also used to search for Epidemiology is also used to search for causes and other factors that influence the causes and other factors that influence the occurrence of occurrence of health-related state health-related state oror events events. . The latter is called The latter is called analytic epidemiologyanalytic epidemiology

Descriptive epidemiology provides the Descriptive epidemiology provides the What, What, Who, When and Where.Who, When and Where.

WHATWHAT is the health problem , disease or event and what are its is the health problem , disease or event and what are its

manifestations and characteristics ?manifestations and characteristics ?

WHOWHO is affected with reference to age ,sex, social is affected with reference to age ,sex, social

class, ethnic, occupation, heredity and personal habits ?class, ethnic, occupation, heredity and personal habits ?

WHENWHEN does it happen, in terms of days, months, seasons or does it happen, in terms of days, months, seasons or

years ? years ?

WHEREWHERE does the problem occur, in relation to place of residence, does the problem occur, in relation to place of residence,

geographical distribution and place of exposure ?geographical distribution and place of exposure ?

Analytic epidemiology attempts to provide the Analytic epidemiology attempts to provide the Why, How and So WhatWhy, How and So What

HOWHOW does the health problem, disease or event occur, and does the health problem, disease or event occur, and what is its association with specific conditions, agents, vectors, what is its association with specific conditions, agents, vectors, sources of infection, susceptible groups and other contributing sources of infection, susceptible groups and other contributing factors ?factors ?

WHYWHY does it occur, in terms of the reasons for its persistence does it occur, in terms of the reasons for its persistence or occurrence ?or occurrence ?

SO WHATSO WHAT interventions have been implemented as a result interventions have been implemented as a result of the information gained and what was their effectiveness ? Have of the information gained and what was their effectiveness ? Have there been any improvements in health status ?there been any improvements in health status ?

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What is hospital What is hospital epidemiology?epidemiology?

The fundamental roles of The fundamental roles of hospital epidemiology are hospital epidemiology are to:to: Identify problemIdentify problem Identify risksIdentify risks Understand risksUnderstand risks Eliminate or minimize Eliminate or minimize

risksrisks

How many peoples influenced by the How many peoples influenced by the disease? Since when the disease disease? Since when the disease started, and do the number of cases started, and do the number of cases tend to increase or decrease by time?tend to increase or decrease by time?

Do the disease burdened on a specific Do the disease burdened on a specific group of Age, gender, place, group of Age, gender, place, occupation, religion, economic status occupation, religion, economic status groups, marriage status, education?groups, marriage status, education?

What is the probable cause or risk What is the probable cause or risk factor that make the disease factor that make the disease frequency?frequency?

Which of the cause / risk factors Which of the cause / risk factors manageble?manageble?

What are the effective solution to What are the effective solution to control the disease ?control the disease ?

What questionsWhat questionsCan be answered by Can be answered by

Epidemiological Approach ? Epidemiological Approach ?

Case definition is a set of Case definition is a set of standard criteria for deciding a standard criteria for deciding a person has a particular disease person has a particular disease (health related condition) or not(health related condition) or not

A Case definition consists of A Case definition consists of clinical criteria include : clinical criteria include : (symptoms/subjective (symptoms/subjective complaints, signs/objective complaints, signs/objective physical finding and laboratory physical finding and laboratory test) test)

For example : in an outbreak of bloody For example : in an outbreak of bloody diarrhea caused by infection with E coli O diarrhea caused by infection with E coli O 157:H7, investigators defined cases in the 157:H7, investigators defined cases in the following three classes :following three classes :

Definite case Definite case : E coli O157:H7 isolated from a : E coli O157:H7 isolated from a stool culture with gastrointestinal symptoms stool culture with gastrointestinal symptoms

Probable case Probable case : Bloody diarrhea with : Bloody diarrhea with gastrointestinal symptomsgastrointestinal symptoms

Possible casePossible case : Diarrhea and gastrointestinal : Diarrhea and gastrointestinal symptomssymptoms

What kind of epidemiologicalWhat kind of epidemiologicaltechnique needed in Community Diagnosistechnique needed in Community Diagnosis

The Disease Frequency The Disease Frequency measurement:measurement: Prevalence and Incidence Prevalence and Incidence

raterate TheThe trendstrends of Prevalence & of Prevalence &

IncidenceIncidence TheThe distributiondistribution of prevalence of prevalence

or incidence rate by age, sex, or incidence rate by age, sex, occupation, socio-economic occupation, socio-economic groups, place, religionsgroups, place, religions

Formulate Formulate HypothesisHypothesis about the about the risk factors (use la londe model)risk factors (use la londe model)

Test hypothesisTest hypothesis

SCHEME FOR AN EPIDEMIOLOGICAL STUDY SCHEME FOR AN EPIDEMIOLOGICAL STUDY CYCLECYCLE

DESCRIPTIVE STUDIES

MODEL BUILDING FORMULATION OF HYPOTHESIS

ANALYSIS OF RESULTS, SUGGEST FURTHER-DESCRIPTIVE AND NEW HYPOTHESIS

ANALYTICAL STUDIES

- X - SECTIONAL

- CASE-CONTROL STUDY

- COHORT

- CLINICAL TRIALS

- FIELD TRIALS

EXPERIMENTAL STUDIES :

TEST HYPOTHESIS

RESEARCH DESIGN IN EPIDEMIOLOGYRESEARCH DESIGN IN EPIDEMIOLOGY

OBSERVATIONAL STUDIES (NO CONTROL OVER EXPOSURE)

NO COMPARISON GROUP

THE EPIDEMIOLOGY STUDY

EXPERIMENTAL STUDIES

(INFESTIGATOR DETERMINE) WHO EXPOSED OR NOT EXPOSED

ANALYTIC

CASE REVIEW

SURVEILLANCE SURVEY CROS SEC TIONAL STUDY

CASE CON TROL STUDY

COHORT STUDY

DESCRIPTIVE

COMPARISAN GROUP

5 CRITERIA CAUSAL ASSOCIATION5 CRITERIA CAUSAL ASSOCIATION

1.TEMPORAL RELATIONSHIP --> means exposure to the causal factor (risk factor) must precede development of the disease (effect)

2. STRENGHT OF ASSOCIATION (RR> 4) --> Strength refers to the size/magnitude of RR (not the p value or degree of statistically significance which can be increased by increasing the sample size).

3. CONSISTENCY (C) AND REPLICATION (R)C--> means different studies resulted in the same

associationR--> means repetition of the same study resulted

in the same association.

4 SPECIFICITY/DOSE-RESPONSE RELATIONSHIPSPECIFICITY/DOSE-RESPONSE RELATIONSHIP

Measures the degree to which one particular exposure Measures the degree to which one particular exposure

produces one specific disease.produces one specific disease.

5 COHERENCE WITH EXISTING KNOWLEDGE (BIOLOGICAL COHERENCE WITH EXISTING KNOWLEDGE (BIOLOGICAL

PLAUSIBILITY)PLAUSIBILITY)

Support for the causal of an association exist if a causal Support for the causal of an association exist if a causal

interpretation is plausible in term of current knowledge interpretation is plausible in term of current knowledge

about the factor and the disease.about the factor and the disease.

PRINCIPLES OF CAUSALITYPRINCIPLES OF CAUSALITY(SEVEN POINTS)(SEVEN POINTS)

1.1. There should be evidence of a strong There should be evidence of a strong association between the risk factor and the association between the risk factor and the disease ( Relative risk, odds ratio and disease ( Relative risk, odds ratio and prevalence ratio)prevalence ratio)

2.2. There should be evidence that exposure to There should be evidence that exposure to the risk factor preceded the onset of diseasethe risk factor preceded the onset of disease

3.3. There should be a plausible biological There should be a plausible biological explanationexplanation

4.4. The association should be supported by The association should be supported by other investigations in different study other investigations in different study settingsetting

5. There should be evidence of reversibility 5. There should be evidence of reversibility of the effect. ( That is, if the “cause” is of the effect. ( That is, if the “cause” is removed the “effect” should also removed the “effect” should also disappear, or at least be less likely)disappear, or at least be less likely)

6. There should be evidence of a dose 6. There should be evidence of a dose response effect.( That is, the greater the response effect.( That is, the greater the amount of exposure to the risk factor, the amount of exposure to the risk factor, the greater the chance of disease)greater the chance of disease)

7. There should be no convincing alternative 7. There should be no convincing alternative explanation. ( For instance, the association explanation. ( For instance, the association should not be explainable by confounding)should not be explainable by confounding)

NATURAL HISTORY OF DISEASENATURAL HISTORY OF DISEASE

Natural history of disease refers to the Natural history of disease refers to the progress of a disease process in an progress of a disease process in an individual over time, individual over time, in the absence of in the absence of intervention.intervention.

The process begins with exposure to or The process begins with exposure to or accumulation of factors capable of causing accumulation of factors capable of causing disease. Without medical intervention, the disease. Without medical intervention, the process ends with recovery, disability, or deathprocess ends with recovery, disability, or death

STAGE OF SUSCEPTIBILITY

STAGE OFSUBCLINICAL DISEASE

STAGE OF CLINICAL DISEASE

STAGE OFDISABILITY OR DEATH

EXPOSURE

PATHOLOGIC CHANGES

ONSET OF SYMPTOMS

USUAL TIME OF DIAGNOSIS

NATURAL HISTORY OF DISEASE

WITHOUT MEDICAL INTERVENTION • RECOVERY• DISABILITY• DEATH

SPECTRUM OF DISEASE

NATURAL HISTORY OF DISEASENATURAL HISTORY OF DISEASE

For infectious disease, the exposure usually For infectious disease, the exposure usually is microorganism. For infectious disease the is microorganism. For infectious disease the period of subclinical is called period of subclinical is called the incubation the incubation periodperiod

For cancers, the critical factors may require For cancers, the critical factors may require both cancer initiators, such as asbestos both cancer initiators, such as asbestos fibers or components in tobacco smoke (for fibers or components in tobacco smoke (for lung cancer) and cancer promoters, such as lung cancer) and cancer promoters, such as estrogens (for endometrial cancer). For estrogens (for endometrial cancer). For chronic disease the period of subclinical is chronic disease the period of subclinical is called called the latency period the latency period

DISEASES CAUSATIONSDISEASES CAUSATIONS

MOSTLY MULTIFACTORIALS (> 1 factor)MOSTLY MULTIFACTORIALS (> 1 factor)

2 THEORY :2 THEORY : EPIDEMIOLOGICAL TRIANGLE EPIDEMIOLOGICAL TRIANGLE

MODEL;MODEL; LA LONDE (Henry L Blum) MODELLA LONDE (Henry L Blum) MODEL..

EPIDEMIOLOGICAL TRIANGLE EPIDEMIOLOGICAL TRIANGLE MODELMODEL

The arising disease, is always a result of total The arising disease, is always a result of total interaction of 3 factors:interaction of 3 factors: The Destructive power of AGENT OF DISEASE, The Destructive power of AGENT OF DISEASE,

as an absolute factor that must be exist as the as an absolute factor that must be exist as the cause.cause.

The Defensive Power of HUMAN HOST as the The Defensive Power of HUMAN HOST as the target of agent of disease, andtarget of agent of disease, and

The Supporting Power of the ENVIRONMENT to The Supporting Power of the ENVIRONMENT to destructive power of agent of disease or to destructive power of agent of disease or to protective power of human hostprotective power of human host

Environment

Destructive power of Agent of

diseases

Resistance of Human host

against disease

DETERMINANT OF HEALTHEPIDEMIOLOGICAL TRIANGLE MODEL

AGENT OF DISEASESAGENT OF DISEASES

PhysicalPhysical agent: Temperature, dust, gas, light, agent: Temperature, dust, gas, light, noise, radiation, etcnoise, radiation, etc

Chemical AgentChemical Agent : : Acid, Base, metal, Organic Acid, Base, metal, Organic compound, food aditive, etccompound, food aditive, etc

Biological agent : BacteryBiological agent : Bactery, Insect, Allergen, , Insect, Allergen, Animal’s bites, etcAnimal’s bites, etc

Intrinsic agentIntrinsic agent : : Gen, hereditary disorders;Gen, hereditary disorders; Psychologial agentPsychologial agent : Mental : Mental Stress;Stress;

DESTRUCTIVE POWER OF AGENT DESTRUCTIVE POWER OF AGENT OF DISEASEOF DISEASE

DETERMINED BY :DETERMINED BY : Quantity of agentsQuantity of agents;; Duration of contact with agent of disease;Duration of contact with agent of disease; Area of contact between agent of disease and Area of contact between agent of disease and

body of human host;body of human host; Basic characteristic of Basic characteristic of agent of disease : agent of disease :

Corosive, Allergen, Toxic, Carcinogenic, Corosive, Allergen, Toxic, Carcinogenic, Mutagenic, Invasive, etc;Mutagenic, Invasive, etc;

Tissue resistance of human host against Tissue resistance of human host against agent of diseaseagent of disease

HOST RESISTANCEHOST RESISTANCE Host resistance against destructive Host resistance against destructive

power of agent of disease, power of agent of disease, determined by :determined by : Genetic factors;Genetic factors; Mental & Spiritual stabilityMental & Spiritual stability Nutritional status;Nutritional status; Physical fitness;Physical fitness; Immunity;Immunity;

ENVIRONMENTAL FACTORSENVIRONMENTAL FACTORS

EFFECT AGAINST AGENT OF DISEASE :EFFECT AGAINST AGENT OF DISEASE : Increase /decrease number of agent of disease, Increase /decrease number of agent of disease,

duration of contact, area of contact and destructive duration of contact, area of contact and destructive power of agent of disease; power of agent of disease;

ex ex High air temperature lower the body indurance High air temperature lower the body indurance EFFECT AGAINST HUMAN RESISTANCEEFFECT AGAINST HUMAN RESISTANCE : :

Increase / decrease psicho-bio-physical indurance ;Increase / decrease psicho-bio-physical indurance ; ex ex Food production determine the nutritional status Food production determine the nutritional status

of population.of population.

DETERMINANT OF HEALTHDETERMINANT OF HEALTHLA LONDE MODELLA LONDE MODEL

LIFE STYLE

PSYCHO-BIOLOGICAL ENDURANCE

ENVIRONMENT• Biological

• Social

HEALTH SERVICE

PROGRAMSHealth

problem

ThreeThree terms are used to describe an infectious terms are used to describe an infectious disease according to the various outcomesdisease according to the various outcomes

Infectivity refers to the proportion of Infectivity refers to the proportion of exposed persons who become infected.exposed persons who become infected.

Pathogenicity refers to the proportion of Pathogenicity refers to the proportion of infected persons who develop clinical infected persons who develop clinical diseasedisease

Virulence refers to the proportion of Virulence refers to the proportion of persons with clinical who become severely persons with clinical who become severely or dieor die

Chain of infectionChain of infection

Transmission of disease occur when the Transmission of disease occur when the agent leaves its agent leaves its reservoir reservoir or host through or host through a a portal of exit,portal of exit, and is conveyed by some and is conveyed by some mode of transmissionmode of transmission, and enters through , and enters through an appropriate an appropriate portal of entry portal of entry to to susceptible host. The process is called the susceptible host. The process is called the chain of infection. chain of infection.

RESERVOIRRESERVOIR

The reservoir of an agent is the habitat in The reservoir of an agent is the habitat in which an infectious agent normally lives, which an infectious agent normally lives, grows and multiplies.grows and multiplies.

Reservoir include human, animal and the Reservoir include human, animal and the environment environment

Two type of human reservoirTwo type of human reservoir

CarrierCarrier is person without apparent disease who is person without apparent disease who is capable of transmitting the agent to others. is capable of transmitting the agent to others.

Asymptomatic carriers Asymptomatic carriers , who never show , who never show symptom during the time they are infected.symptom during the time they are infected.

Incubatory or convalescent carriers Incubatory or convalescent carriers who are who are capable of transmission before or after they are capable of transmission before or after they are clinical ill clinical ill

Two type of human resevoirTwo type of human resevoir

Chronic carriers Chronic carriers is one who continues to is one who continues to harbor an agent for extended time (months harbor an agent for extended time (months or years).or years).

Exp : Hepatitis B, typhoid fever)Exp : Hepatitis B, typhoid fever) Symptomatic persons are usually less likely Symptomatic persons are usually less likely

to transmit infection widely because their to transmit infection widely because their symptom increase their likelihood of being symptom increase their likelihood of being diagnosed and treated.diagnosed and treated.

Portal of exitPortal of exit

The path by which an agent leaves the The path by which an agent leaves the source host. The portal of exit usually source host. The portal of exit usually corresponds to the site at which the agent corresponds to the site at which the agent is localized.is localized.

Examp : tubercle bacilli and influenza virus Examp : tubercle bacilli and influenza virus exit the respiratory tract, cholera vibrios in exit the respiratory tract, cholera vibrios in feces.feces.

Modes of transmissionModes of transmission DirectDirect

Direct contact (kissing, sexual intercourse)Direct contact (kissing, sexual intercourse)

Droplet spread ( refers to spray with relative Droplet spread ( refers to spray with relative

large. Sneezing, coughing even talking)large. Sneezing, coughing even talking) Indirect ( an agent is carried from a reservoir to Indirect ( an agent is carried from a reservoir to

a susceptible host by a susceptible host by suspended air particle, suspended air particle,

vector and vehicle)vector and vehicle)

Airborne (The nuclei less than 5 Airborne (The nuclei less than 5 μμ/micron)/micron)

VehicleborneVehicleborne

Vectorborne : Mechanical, BiologicVectorborne : Mechanical, Biologic

Portal of entryPortal of entry

An agent enters a susceptible host through An agent enters a susceptible host through a portal of entry.a portal of entry.

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NEW PARADIGM:NEW PARADIGM:CONCEPT OF HEALTH CONCEPT OF HEALTH

ILLNESSES AND ILLNESSES AND DISEASEDISEASE

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HEALTHHEALTHHEALTHHEALTH Health is a state of individual or community’s:Health is a state of individual or community’s:

physical, mental, spiritual, dan socialphysical, mental, spiritual, dan social wellbeing and wellbeing and not merely a condition of free from illness and injury, not merely a condition of free from illness and injury, so that every individual can achieve his/her social so that every individual can achieve his/her social and economic productivity (Health Law No 23 th and economic productivity (Health Law No 23 th 1992).1992).

Physical, mental, spiritual dan social component of Physical, mental, spiritual dan social component of health are health are inter-related one to each other,inter-related one to each other, and create a and create a health conditionshealth conditions of individuals or community. of individuals or community.

The Integration of the 4 components of health, create The Integration of the 4 components of health, create an an interval scale of health states or levels of healthinterval scale of health states or levels of health ranges from ranges from low health levellow health level to a to a perfect health level.perfect health level.

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COMPONENTS OF HEALTHCOMPONENTS OF HEALTHAND THE LEVEL OF HEALTHAND THE LEVEL OF HEALTH

PERFECT STRUCTURE AND FUNCTIONS

STRUCTURAL & FUNCTIONAL DEFECTS

PHYSICAL MENTAL SOCIAL SPIRITUAL

PerfectHealth

Worst

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Consequences Consequences Since the doctor’s main jobs are analysing Since the doctor’s main jobs are analysing

whether her/his patients are healthy or whether her/his patients are healthy or not, meaning that they must conclude the not, meaning that they must conclude the existing conditions of the patient’s body & existing conditions of the patient’s body & mind structure and/or function deviate mind structure and/or function deviate from normality.from normality.

To be a skillfull doctors, the Medical To be a skillfull doctors, the Medical Students must:Students must: Have Have a good knowledge and skillsa good knowledge and skills in examining in examining

the structure and functions of normal and the structure and functions of normal and abnormal individuals (physically, mentally and abnormal individuals (physically, mentally and socially);socially);

Have a good knowledge and skills Have a good knowledge and skills to stop the to stop the changing process of body structures and changing process of body structures and functions and then make it back to normal.functions and then make it back to normal.

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WHAT THE DOCTOR’S CANDIDATE MUST WHAT THE DOCTOR’S CANDIDATE MUST LEARNLEARN

1.1. The normal body and mind structure and functions The normal body and mind structure and functions ((anatomy, histology, physiology, biochemistryanatomy, histology, physiology, biochemistry))

2.2. Non-normal structure and functions Non-normal structure and functions ((microbiology, microbiology, parasitology, clinical pathology, anatomy parasitology, clinical pathology, anatomy pathologypathology))

3.3. Laboratory and clinical skills to practice medical Laboratory and clinical skills to practice medical profession profession ((Clinical Pre internship or ClerkshipClinical Pre internship or Clerkship))

4.4. Management skills and knowledge of medical care Management skills and knowledge of medical care services services ((Public HealthPublic Health))

5.5. Intelectual skills and knowledge Intelectual skills and knowledge ((Methodology, Methodology, Science ProjectsScience Projects))

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ILLNESS VS DISEASESILLNESS VS DISEASES

ILLNESSILLNESS One’s perception on One’s perception on

the signs of the the signs of the deviations / deviations / abnormality of bio-abnormality of bio-psycho-socials psycho-socials structure or/and structure or/and functions of their functions of their own or other’sown or other’s

Ex. Ex. Headache, Headache, Fever, painFever, pain, etc, etc

DISEASEDISEASE One’s expectations One’s expectations

upon causal factor/s upon causal factor/s that stimulate the that stimulate the structural and structural and functional deviation functional deviation of bio-psycho-social of bio-psycho-social on their own or otherson their own or others

Ex. Ex. HIV, MalariaHIV, Malaria, etc, etc

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The Facts about DiseaseThe Facts about Disease Every disorder/diseases must be caused by at least Every disorder/diseases must be caused by at least

one internal or external factors (mostly one internal or external factors (mostly multifactorsmultifactors););

The degree of the disorders, depend on The degree of the disorders, depend on the the destructive power of the causal factors,destructive power of the causal factors, and and the the protective power of the individuals body and protective power of the individuals body and mentality.mentality.

There is always time lag (There is always time lag (incubation periodincubation period) ) between the exposure time of factors, and the between the exposure time of factors, and the development of sign or symptoms of diseases;development of sign or symptoms of diseases;

The The prevention of diseasesprevention of diseases, is actually a process , is actually a process to stop the worse development of diseases, as to stop the worse development of diseases, as

early as possible;early as possible; to normalize the structural and functional to normalize the structural and functional

deviation to achieve the highest social and deviation to achieve the highest social and economic productivityeconomic productivity..

USESUSES

Population or community health assesment. Population or community health assesment.

To do this, we must find answers to many To do this, we must find answers to many questions : What are the actual and potential questions : What are the actual and potential health problems in the community ?, Where are health problems in the community ?, Where are they ?, Who is at risk ?, Which problems are they ?, Who is at risk ?, Which problems are declining over time ?, Which ones are increasing declining over time ?, Which ones are increasing or have the potential to increase ?, How do these or have the potential to increase ?, How do these patterns relate to the level and distribution of patterns relate to the level and distribution of services available ?.services available ?.

Individual decisions.Individual decisions. People may not realize People may not realize that they use epidemiologic information in their that they use epidemiologic information in their daily decisions. daily decisions.

Completing the clinical picture.Completing the clinical picture.

When studying a disease outbreak, When studying a disease outbreak, epidemiologists depend on clinical physicians and epidemiologists depend on clinical physicians and laboratory scientists for the proper diagnosis of laboratory scientists for the proper diagnosis of individual patients. But epidemiologist also individual patients. But epidemiologist also contribute to physicianscontribute to physicians,, understanding of the understanding of the clinical picture and natural history of disease.clinical picture and natural history of disease.

Search for causes.Search for causes.

Much of epidemiologic research is devoted to a Much of epidemiologic research is devoted to a search for causes, factors which influence onesearch for causes, factors which influence one,,s s risk of disease. risk of disease.

Health StatusHealth Status

For example : Prevalence, IncidenceFor example : Prevalence, Incidence Evaluation of intervention.Evaluation of intervention.

To assess the effectivenessTo assess the effectiveness of preventive and of preventive and

therapeutic treatments.therapeutic treatments.

To assess the impact of health-care servicesTo assess the impact of health-care services

To predict future health care needs To predict future health care needs

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GOOD LUCK !GOOD LUCK !