KONSEP DASAR
EPIDEMIOLOGI
OUTLINE
Definisi dan Konsep Dasar Epidemiologi
Ruang Lingkup Epidemiologi
Konsep Dasar Timbulnya Penyakit
Definitions
Study Design
Measures of Disease Frequency Measures of Association
Definitions
Epidemiology is the study of how disease is
distributed in populations and the factors that
determine that distribution (Gordis, 2013)
The science concerned with the study of the
factors determining and influencing the
frequency and distribution of disease, injury, and other health-related events and their
STUDY DESIGN
Examining the distribution of a disease in a population, and observing the basic features of its distribution in terms of time, place, and person.
Typical study design: community health survey
(approximate synonyms - cross-sectional study,
descriptive study)
Testing a specific hypothesis about the relationship of a disease to a putative
cause, by conducting an epidemiologic study that relates the exposure of interest to the disease of interest.
Typical study designs:
cohort, case-control, experimental
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 a time 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 a time period. Value from 0 to infinity
3. Prevalence (Point Prevalence):
Number of new and old cases at a point of time Population
Sporadic level: occasional cases occurring at irregular intervals
Endemic level: persistent occurrence with moderate to high level
Epidemic or outbreak: occurrence clearly in
excess of the expected level for a given time period
Pandemic: epidemic spread over several countries or continents, affecting a large number of people
Attack rate:
# cases of disease that develop during
________defined period_______
# in pop. at risk at start of period
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 all things happening
ODDS= the chances of something happening the chances of it not happening
PROPORTION
MEASURES OF DISEASE ASSOCIATION (2)
The relative risk is a ratio of two risks.
Assume that among the 100 people at risk, 50 are men and 50 women. If 15 men and 5 women develop
influenza, then the relative risk of developing influenza in men, as compared with women, is:
Risk in men = 15/50 divided by
Risk in women = 5/50
15/50 ÷ 5/50 = 3.0
Measures of Disease Association (3)
We conclude that the odds of men getting influenza over the year are 3.9 times as high as the odds of women getting influenza.
Use of Epidemiology Issues in Epidemiology
- - Bias
- - Confounding
- - Hill’s Causal Criteria
Use of Epidemiology
Causation
Natural History
Description of
Health Status
Trias Bloom (Konsep Keseimbangan) Natural History of Disease
The Basic Triad Of Descriptive Epidemiology
TIME
Description of Disease Distribution
in the Population
Disease affects
mostly people under five years of age
Disease affects people living
alongside the river
The Basic Triad Of Analytic Epidemiology
HOST
Agent
• Nutritional status
• Health status
• Infectivity
• Pathogenicity
• Virulence
• Immunogenicity
• Antigenic stability
• Survival
• Weather
• Housing
• Geography
• Occupational setting
• Air quality
• Food
Susceptible
Infectious period
Non-infectious
Time Time
Definition
Screening and Surveillance Difference
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 action to prevent the disorder or condition or its
Surveillance involves investigating the
distribution and possible causes of diseases and conditions within the population.
Active Surveillance (based on active case finding)
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 orang lagi yg membutuhkan pengobatan. Angka
Pada suatu wilayah kerja, diketahui jumlah karyawan
laki-laki yang menderita HIV pada tanggal 1 Januari 2012 sebanyak 50 dari 1000 orang. Pada tanggal 1 Januari 2013 terdapat 62 kasus dari 1000 orang
termasuk 50 orang tang terdeteksi sebelumnya.
Berapa prevalensi HIV pada tanggal 1 Januari
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
Questions?
