pengukuran penyakit dalam populasi 3/2014 disiapkan oleh prof. dr.drh.pratiwi, ts. ms...

PTS-RST-PKH-3 -2014 1

Pengukuran penyakit dalam populasi 3/2014

DISIAPKAN OLEH PROF. DR.DRH.PRATIWI, TS. MS

DRH.ROSITAWATI, I. MP

2/22/2014


Ruang Lingkup & Kegiatan Epidemiologi

2/22/2014


Ilmu yang dibutuhkan Epidemiolog• Public health :

– Sebab fokus atau penekanan bidang ilmu epidemiologi adalah pencegahan penyakit

• Medik klinik : – Sebab penekanan epidemiologi adalah pada klasifikasi & diagnosis penyakit

• Patofisiologi :– Kebutuhan pemahaman yang baik tentang mekanisme biologi suatu penyakit

• Statistik :– Untuk kuantifikasi frekuensi penyakit dll

• Sain sosial :– Perlu memahami konteks sosial di wilayah terjadinya penyakit

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Endemic• the constant occurrence of a disease that

commonly presents in a particular place with stability in the level of infection

Endemic pattern

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Sporadic pattern

Sporadic: An irregular occurrence of a disease that commonly presents in a particular place

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Epidemic

• the occurrence of a disease that the level of infection exceeds that normal expectancy in a specific region, spreads rapidly and usually lasts for a limited period of time– Pandemic: widespread epidemic that affects a large part

of population in many countries– Epizootic: epidemic that involves animal host population

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Epidemic pattern

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Epidemic patterns

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Disease outbreak

• survey of disease data• count of cases• describe –person / animal–place–time

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Environment

Host Agent

Environment

Host

Agent

Environment

Host

Agent

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Environment

Host Agent

Environment

Host Agent

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Natural history of disease

Normal

Risk factors

Disease

Death

recover

disabled

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Infe

ction

Susceptible

Susceptible

Dynamics of infectiousness

Dynamics of disease

Incubation period

Symptomaticperiod

Non-diseased

Latentperiod

Infectious period

Non-infectious

Infe

ction

Time

Time

(www)

Timeline for Infection

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http://www.pubhealth.ku.dk/epi_en/Uddannelser/fsv7sem/noter/fsv7s-infdisepi-E05-UK-for_home_page.ppt/


Iceberg principle of disease

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Iceberg (phenomenon) Principle

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Iceberg phenomenon

death

disability

Clinical

Clinical

Pre-clinical

Susceptibility

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•Clinical•Sub-clinicalOutcome

Host susceptibility

Exposure

Agent source

Steps in the Disease Process

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Type of Epidemiology (Study design)• Descriptive epidemiology– survey: time, place, person– Case report, case series

• Analytical epidemiology (risk factors)– Cross-sectional– Cohort– Case-control

• Experimental epidemiology– Randomized control trial– Clinical trial– Community trial

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Measuring disease frequency has several (8) components:

• Classifying & categorizing disease• Deciding what constitutes a case of disease in

a study• Finding a source for ascertaining the cases• Defining the population at risk of disease

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Measuring disease frequency has several (8) components:

• Defining the period of time of risk of disease• Obtaining permission to study people/animal• Making measurement of disease frequency• Relating cases to population and time at risk

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Epidemiology study

Distribution Risk factors

Analytic studyDescriptive study

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Descriptive epidemiology

Epidemiology

Distribution

Risk factors

Time

Place

Person

Analytic study

Descriptive study

Etiology

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• What (How much): occurred• Who: animals or humans• When: time• Where: place

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• Detection of individual case• Detection of outbreaks• Measuring the impact of disease• Understand the nature of a disease• Understand the way that disease spreads and is

distributed

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• Generate hypotheses and ideas for further research• Evaluation of prevention and control measures• Support planning activities for animal health program

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Basic Measures and Tools of Descriptive Epidemiology

• Data collection• classification / organization• summarizing• presentation

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Incidence rate

Incidence

No. of new cases of a disease occurring in the population

during a specified period of time

No. of persons who are at risk of developing the disease during that period of time x100

• the number of NEW cases that develop over a certain time period.

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No. of cases of a disease present in the population at a specified time

No. of persons in the population at that specified time

Prevalence rate

x100

• the number of existing cases including old and new cases that have developed at some point during a time period.

Prevalence

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Incidence and Prevalence

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Example

Question Type of measure

Do you currently have asthma? Point prevalence

Have you had asthma during the last 2 years?

Period prevalence

Have you ever had asthma? Cumulative incidence

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No of deaths

PopulationMortality rate =

No of deaths

No of clinically illCase fatality rate =

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No of clinically ill

PopulationMorbidity rate =

No of infected

PopulationInfection rate =


Analytical epidemiology

• How: adjust policy and response• Why: prevent and control

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Cross-sectional

• A random sample of individuals from a population is taken at a point in time

• Surveys to collect data

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Cross-sectional

• Advantages: – quick to conduct and cost is moderate compared with

other study designs.

• Disadvantages: – cannot provide information on the incidence of disease in

a population only an estimate of prevalence– Difficult to investigate cause and effect relationships

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Cohort

• Comparing disease incidence over time between groups

• Prospective cohort– Non-disease case– Expose and non-expose

• Retrospective cohort– Disease case– Evaluated for evidence of exposure to the agent

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Cohort

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Cohort

• Advantages:– monitored over time for disease occurrence– estimates of the absolute incidence of disease in exposed

and non-exposed

• Disadvantages:– long follow-up period– case of rare diseases large groups are necessary– Losses to follow-up– expensive

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Case-control

• Comparing the frequency of past exposure between cases who develop the disease (or other outcome of interest) and controls chosen to reflect the frequency of exposure in the underlying population at risk

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Case-control• Advantages:– an efficient method for studying rare diseases– subjects have experienced the outcome of interest at the

start of the study– quick to run and cheaper than other study

• Disadvantages:– Can not provide information on the disease incidence in a

population– Reliant on the quality of past records or recollection of

study participants– Difficult to ensure an unbiased selection of the control

group

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Bingung

hiks

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Sampai minggu ke 4

2/22/2014

pengukuran penyakit dalam populasi 3/2014 disiapkan oleh prof. dr.drh.pratiwi, ts. ms...

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