Post on 02-Mar-2018
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KONSEP DASAREPIDEMIOLOGI
Vitri Widyaningsih
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OUTLINE
Definisi dan Konsep Dasar Epidemiologi
Ruang Lingkup Epidemiologi
Konsep Dasar Timbulnya Penyakit
Penemuan Penyakit secara Screening
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Definitions
Study Design
Measures of Disease Frequency
Measures of Association
Definisi dan Konsep Dasar dalam
Epidemiologi
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What is Epidemiology?
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Definitions
Epidemiology is the study of how disease isdistributedin populations and the factors thatdeterminethat distribution (Gordis, 2013)
The science concerned with the study of thefactors determining and influencing thefrequency and distribution of disease, injury,and other health-related events and their
causes in a defined human population. Also,the sum of knowledge gained in such a study.(Dorland, 2007)
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STUDY DESIGN
Examining the distribution ofa disease in a population,
and observing the basicfeatures of its distributionin terms of time, place, andperson.
Typical study design:
community health survey(approximate synonyms -cross-sectional study,descriptive study)
Testing a specific hypothesisabout the relationship of a
disease to a putativecause, by conducting anepidemiologic study thatrelates the exposure ofinterest to the disease ofinterest.
Typical study designs:cohort, case-control,experimental
Descriptive Analytic
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Epidemiologic Study Designs
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Measure of Disease Frequency
1. Cumulative Incidence (Incidence, Risk, I, R)=
Number of new case over a time period
Population at risk at the beginning
- Indicates the risk for the disease to occur in population at risk over atime period. Value from 0 to 1.
2. Incidence Density (Incidence Rate, ID, IR)=
Number of new case over a time period
Person time at risk
Indicates the velocity (speed) of the disease to occur in population over atime period. Value from 0 to infinity
3. Prevalence (Point Prevalence):
Number of new and old cases at a point of time
Population
Indicates burden of disease. Value from 0 to 1.
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Sporadic level: occasional cases occurring at
irregular intervals
Endemic level: persistent occurrence withmoderate to high level
Epidemic or outbreak: occurrence clearly in
excess of the expected level for a given time period
Pandemic: epidemic spread over several countriesor continents, affecting a large number of people
Levels of Disease Occurence
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Attack rate:
# cases of disease that develop during
________defined period_______
# in pop. at risk at start of period
(usually used for infectious disease outbreaks)
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Measures of Disease Frequency
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Measures of Disease Frequency
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Measures of Disease Frequency
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Measures of Disease Association
The chances of something happening can be
expressed as a risk or as an odds:
RISK= the chances of something happening
the chances of allthings happening
ODDS= the chances of something happeningthe chances of itnothappening
PROPORTION
RATIO
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MEASURES OF DISEASE ASSOCIATION (2)
The relative riskis a ratio of two risks.
Assume that among the 100 people at risk, 50 are menand 50 women. If 15 men and 5 women developinfluenza, then the relative risk of developing influenzain men, as compared with women, is:
Risk in men = 15/50
divided byRisk in women = 5/50
15/50 5/50 = 3.0
(Note that from the way the question was put, the tworisks are cumulative incidence rates.)
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Measures of Disease Association (3)
The odds ratio is a ratio of two odds
The odds in men = 15/35divided by
The odds in women = 5/35
15/35 5/45 = 3.9
We conclude that the odds of men getting influenzaover the year are 3.9 times as high as the odds ofwomen getting influenza.
Thought quest ion: note that the odds ratio in thisexample (3.9) is larger than the relative risk (3.0).
Is this always the case? Is this important?
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Use of Epidemiology
Issues in Epidemiology- - Bias
- - Confounding
- - Hills Causal Criteria
Ruang Lingkup Epidemiologi
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Use of Epidemiology
Causation
Natural History
Description of
Health Status
Evaluation of Intervention
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Trias Bloom (Konsep Keseimbangan)
Natural History of Disease
Konsep Dasar TimbulnyaPenyakit
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The Basic Triad Of Descriptive Epidemiology
TIME
PERSONPLACE
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Description of Disease Distribution
in the Population
Disease affects
mostly people under
five years of age
Disease affects
people living
alongside the river
Disease reaches its
peak in frequency in
Week 6
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The Basic Triad Of Analytic Epidemiology
HOST
ENVIRONMENTAGENT
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Agent
Host
Environment
Age
Sex
Genotype
Behaviour
Nutritional status
Health status
Infectivity
Pathogenicity
Virulence
Immunogenicity
Antigenic stability
Survival
Weather
Housing
Geography
Occupational setting
Air quality
Food
Factors Influencing Disease
Transmission
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Natural History of Disease
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Susceptible
Susceptible
Dynamics of
infectiousness
Dynamics of
disease
Incubation
period
Symptomatic
period
Non-diseased
Latent
period
Infectious
period
Non-infectious
Time
Time
Timeline of Infectiousness
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Definition
Screening and Surveillance Difference
Screening
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Definition
Examination of whole populations aims to
detect those at risk of a specific disorder or
condition who are likely to benefit from further
investigations and possibly treatment or actionto prevent the disorder or condition or its
consequences.
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Surveillance involves investigating the
distribution and possible causes of diseases
and conditions within the population.
Active Surveillance (based on active case finding) Passive Surveillance (based on reporting)
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REFRESH YOUR KNOWLEDGE
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Pada 120 siswa SMP pada 1 januari dilakukan
screening anemia. Pada 120 siswa, 30 siswa (1
januari 2005) didiagnosa anemia. Pada 31
desember di skrining ulang, didapatkan 10 oranglagi yg membutuhkan pengobatan. Angka
insidensi :
a. 10/90
b. 30/90c. 10/120
d. 30/120
e. 40/120
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Pada suatu wilayah kerja, diketahui jumlah karyawanlaki-laki yang menderita HIV pada tanggal 1 Januari2012 sebanyak 50 dari 1000 orang. Pada tanggal 1Januari 2013 terdapat 62 kasus dari 1000orangtermasuk 50 orang tang terdeteksi sebelumnya.
Berapa prevalensi HIV pada tanggal 1 Januari2013?
a. 5%
b. 6,2%
c. 1,2% d. 50%
e. 62%
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Sebuah penelitian ingin mencari risiko hipertensi pada PNS.
Didapatkan data sebagai berikut:
Dari data diatas, nilai yang
digunakan untuk menentukan
kekuatan hubungan antar
variable adalah?a) Nilai p
b) Proporsi
c) Frekuensi
d) Ratio Odds
e) Interval kepercayaan
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Dari data diatas, risiko mengalami hipertensi tertinggi
terdapat pada golongan ?
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Questions?
Thank You