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UKURAN DAMPAK DALAM EPIDEMIOLOGI
Putri Handayani, M.KKK
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-effectrelationship 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)
• [Risiko pada kelompok terpajan] – [Risiko pada 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”
Smoke Yes No
Yes 84 2916 3000
No 87 4913 5000
Develop CHD 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
[IK pada kelompok terpajan] - [IK pada kelompok tidak 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] - [Densitasinsidens pada kelompok tidak terpajan]
Ukuran-ukuran dampak
• Ukuran perbedaan efek
– Perbedaan prevalens (PD = Prevalence Differrence)
PD = [Prevalens dalam kelompok terpajan] - [Prevalens dalam kelompok tidak terpajan]
Attributable Risk
Incidence
Exposed Unexposed
Iexposed - Iunexposed
Ukuran-ukuran dampak/efek
• Ukuran perbedaan efek
– Attributable Risk (AR) Percent = AR%
%100Insidens
InsidensInsidensAR%
terpajan
terpajantidakterpajanx
Attributable Risk Percent (AR%)
AR% = (Iexposed – Inonexposed) / Iexposed = “Etiologic fraction”
Smoke Yes No
Yes 84 2916 3000
No 87 4913 5000
Develop CHD
AR% = (28.0 – 17.4) / 28.0 = 37.9%
ISM = 84 / 3000
= 0.028 = 28.0 / 1000
INS = 87 / 5000
= 0.0174 = 17.4 / 1000
(background risk)
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
Exposed Unexposed
Iexposed – Iunexposed RR - 1
------------------------------- = ------------ x 100%
Iexposed 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
terpajantidakpopulasi InsidensInsidensPAR
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%
%100Insidens
InsidensInsidensPAR%
populasi
terpajantidakpopulasix
Population Attributable Risk Percent
PAR% = (Itotal – Inonexposed) / Itotal
Weight Yes No
Obese 850 3650 4500
Slim 250 5250 5500
Diabetes
PAR% = (110 – 45.5) / 110 = 58.6%
1100 8900 10000
IT = 1100 / 10000
= 0.11 = 110 / 1000
INE = 250 / 5500
= 0.0455 = 45.5 / 1000
(background risk)
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
RR -1
I
I -I PF
unexposed
exposed unexposed
PF: Vaccine efficacy
Pop. Cases Cases/1000 RR
Vaccinated 301,545 150 0.49 0.28
Unvaccinated 298,655 515 1.72 Ref.
Total 600,200 665 1.11
0.72 0.28 - 1
0.72 1.72
0.49 - 1.72 PF
Ringkasan ukuran
Tipe
Kuantitas
Matematis
Tanpa
denominator
Dengan
denominator
Enumerasi
Hitung,
angka mutlakRasio Proporsi Rate
Ringkasan ukuran
Tipe
Kuantitas
Matematis
Enumerasi Rasio Proporsi Rate
•RR
•OR
•IDR
•%
•AR%
•PAR%
•Crude
•Spesific
•Adjusted
Ringkasan ukuran
Ukuran
dalam
epidemiologi
Ukuran
Frekuensi
Penyakit
Ukuran
asosiasi
Ukuran efek
/dampak
Ukuran frekuensi penyakit
Ukuran
frekuensi
Penyakit
Insidens Prevalens
Insidens
Kumulatif
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
Perbedaan
efek
Fraksi
Efek
RD
AR
ER
PAR
AR% PAR% PF
RD = Risk Difference
AR = Attributable Risk
ER = Excess Risk
PAR = Population Attributable Risk
PF = Prevented Fraction