Post on 29-Mar-2015
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Pengukuran penyakit dalam populasi 3/2014
DISIAPKAN OLEH PROF. DR.DRH.PRATIWI, TS. MS
DRH.ROSITAWATI, I. MP
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Ruang Lingkup & Kegiatan Epidemiologi
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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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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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Descriptive epidemiology
• What (How much): occurred• Who: animals or humans• When: time• Where: place
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Descriptive epidemiology
• 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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Descriptive epidemiology
• 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 =
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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
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