konsep dasar epidemiologi-mahasiswa - 2014 - vitri widyaningsih

7/26/2019 Konsep Dasar Epidemiologi-Mahasiswa - 2014 - Vitri Widyaningsih

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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 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

konsep dasar epidemiologi-mahasiswa - 2014 - vitri widyaningsih

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