### Dasar-dasar Epidemiologi Pertemuan 11

```UKURAN DAMPAK DALAM
EPIDEMIOLOGI
Nurul Wandasari Singgih
Prodi Kesehatan Masyarakat
Univ Esa Unggul 2012/2013
Measures of Public Health Impact
• Attributable Risk (AR)
Number
• Attributable Risk Percent (AR%)
Percentage
• Population Attributable Risk (PAR) Number
• Population Attributable Risk Percent
(PAR%)
Percentage
Measures of Public Health Impact
IMPORTANT!
They all assume (require) that a cause-effect
relationship exists between the exposure and
the outcome.
Relative Risk vs. Attributable Risk
Relative Risk: Measure of the strength of
association, and indicator used to assess the
possibility of a causal relationship.
Attributable Risk:
Measure of the potential
for prevention of disease if the exposure could
be eliminated (assuming a causal relationship).
Relative Risk vs. Attributable Risk
Relative Risk:
• Etiology
Attributable Risk:
• Policy decisions
• Funding decisions
(e.g. prevention
programs)
Tipe ukuran yang digunakan dalam epidemiologi
• Ukuran efek/dampak
– Merefleksikan dampak suatu faktor pada frekuensi
atau risiko dari suatu masalah (outcome)
kesehatan
– Merefleksikan kelebihan jumlah kasus karena
suatu faktor (attributable) atau jumlah kasus yang
dapat dicegah oleh eksposur (pemajan)
Ukuran-ukuran dampak
• Ukuran perbedaan dampak/efek
– Perbedaan risiko = Risk Difference (RD) =
Attributable Risk (AR) = Excess Risk (ER) =
Absolute Risk (AR)
kelompok tidak terpajan]
• Berguna untuk mengukur besarnya masalah kesehatan
masyarakat yang disebabkan oleh suatu pemajan
• bermanfaat untuk penilaian prioritas untuk aksi
kesehatan masyarakat (Public Health Action)
Attributable Risk (AR)
Among the EXPOSED:
How much of the disease that occurs can be
attributed to a certain exposure?
AR
AR%
This is of primary interest to the practicing
clinician.
Attributable Risk (AR)
AR = Iexposed – Inonexposed = “Risk Difference”
Develop CHD
Smoke Yes
No
Yes
84
2916 3000
No
87
4913 5000
ISM = 84 / 3000
= 0.028 = 28.0 / 1000
INS = 87 / 5000
= 0.0174 = 17.4 / 1000
(background risk)
AR = (28.0 – 17.4) / 1000 = 10.6 / 1000
Attributable Risk (AR)
AR = (28.0 – 17.4) / 1000 = 10.6 / 1000
Among SMOKERS, 10.6 of the 28/1000
incident cases of CHD are attributed to the
fact that these people smoke …
Among SMOKERS, 10.6 of the 28/1000
incident cases of CHD that occur could be
prevented if smoking were eliminated.
Ukuran-ukuran dampak
• Ukuran perbedaan dampak/efek
– Perbedaan insidens kumulatif = Cumulative Incidence
Difference= CID
terpajan]
IK = Insidens Kumulatif
Ukuran-ukuran dampak
• Ukuran perbedaan efek
– Perbedaan rate/ perbedaan densitas insidens (IDD =
Insidence Density Difference)
• IDD =
[Densitas insidens dalam kelompok terpajan] - [Densitas
Ukuran-ukuran dampak
• Ukuran perbedaan efek
– Perbedaan prevalens (PD = Prevalence Differrence)
PD = [Prevalens dalam kelompok terpajan] - [Prevalens dalam
kelompok tidak terpajan]
Attributable Risk
Incidence
Iexposed - Iunexposed
Exposed
Unexposed
Ukuran-ukuran dampak/efek
• Ukuran perbedaan efek
– Attributable Risk (AR) Percent = AR%
AR% 
Insidens
 terpajan 
 Insidens
Insidens
 terpajan 
 tidak
terpajan

x 100 %
Attributable Risk Percent (AR%)
AR% = (Iexposed – Inonexposed) / Iexposed =
“Etiologic fraction”
Develop CHD
Smoke Yes
No
Yes
84
2916 3000
No
87
4913 5000
ISM = 84 / 3000
= 0.028 = 28.0 / 1000
INS = 87 / 5000
= 0.0174 = 17.4 / 1000
(background risk)
AR% = (28.0 – 17.4) / 28.0 =
37.9%
Attributable Risk Percent (AR%)
AR% = (28.0 – 17.4) / 28.0
=
37.9%
Among SMOKERS, 38% of the morbidity from
CHD may be attributed to smoking…
Among SMOKERS, 38% of the morbidity from
CHD could be prevented if smoking were
eliminated.
Attributable Risk Percent
Incidence
Iexposed – Iunexposed
RR - 1
------------------------------- = ------------ x 100%
Iexposed
Exposed
Unexposed
RR
Ukuran-ukuran dampak
• Population Attributable Risk (PAR)
– = Attributable Fraction (population) atau Etiologic
Fraction (population) = Population Attributable Risk
Proportion = Population Attributable Risk Fraction
– Proporsi (atau fraksi) rate penyakit pada seluruh populasi
yang mewakili rate penyakit dalam kelompok terpajan
– Rumus PAR
PAR  Insidens
 populasi 
 Insidens
 tidak
terpajan

Ukuran-ukuran dampak
•
Population Attributable Risk Percent (PARP)
attributable fraction (population) atau etiologic
fraction (population)
– Berarti proporsi kasus baru yang dapat dicegah jika pada semua
orang yang tidak terpajan
– Rumus PAR%
PAR% 
Insidens
 populasi 
 Insidens
Insidens
 populasi 
 tidak
terpajan

x 100 %
Population Attributable Risk Percent
PAR% = (Itotal – Inonexposed) / Itotal
Weight
Obese
Slim
IT = 1100 / 10000
Diabetes
Yes
No
850
250
= 0.11 = 110 / 1000
3650 4500
5250 5500
INE = 250 / 5500
= 0.0455 = 45.5 / 1000
(background risk)
1100
8900
10000
PAR% = (110 – 45.5) / 110 =
58.6%
Population Attributable Risk Percent
PAR% = (110 – 45.5) / 110 =
58.6%
In Tampa, 59% of the cases of diabetes may
be attributed to obesity in the population…
In Tampa, 59% of the cases of diabetes could
be prevented if Tampa residents lost
sufficient weight.
Prevented Fraction (PF)
• If relative risk <1
– Proportion of potential new cases which would
have occurred if the exposure had been absent
– Proportion of potential cases prevented by the
exposure
PF 
Iunexposed - Iexposed
Iunexposed
 1 - RR
PF: Vaccine efficacy
Pop.
C ases
C a s e s /1 0 0 0
RR
V a c c in a te d
3 0 1 ,5 4 5
150
0 .4 9
0 .2 8
U n va c c in a te d
2 9 8 ,6 5 5
515
1 .7 2
R e f.
T o ta l
6 0 0 ,2 0 0
665
1 .1 1
PF 
1.72 - 0.49
 0.72
1.72
 1 - 0.28
 0.72
Ringkasan ukuran
Tipe
Kuantitas
Matematis
Tanpa
denominator
Enumerasi
Hitung,
angka mutlak
Dengan
denominator
Rasio
Proporsi
Rate
Ringkasan ukuran
Tipe
Kuantitas
Matematis
Enumerasi
Rasio
Proporsi
Rate
•RR
•OR
•IDR
•%
•AR%
•PAR%
•Crude
•Spesific
Ringkasan ukuran
Ukuran
dalam
epidemiologi
Ukuran
Frekuensi
Penyakit
Ukuran
asosiasi
Ukuran efek
/dampak
Ukuran frekuensi penyakit
Ukuran
frekuensi
Penyakit
Insidens
Insidens
Kumulatif
Prevalens
Incidence
Density
Prevalens
titik
Prevalens
periode
Mortalitas
Ukuran frekuensi penyakit
Ukuran
Rasio
Risk
Ratio
Odds
Rasio
Insidence
Density
Ratio
Prevalence
Ratio
Ukuran frekuensi penyakit
Ukuran
Efek
/dampak
RD = Risk Difference
AR = Attributable Risk
ER = Excess Risk
PAR = Population Attributable Risk
PF = Prevented Fraction
Perbedaan
efek
RD
AR
ER
PAR
Fraksi
Efek
AR%
PAR%
PF
```