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-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) • [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” 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 [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] - [Densitas insidens 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
Iexposed - Iunexposed
Exposed
Unexposed
Ukuran-ukuran dampak/efek • Ukuran perbedaan efek – Attributable Risk (AR) Percent = AR%
AR%
Insidens terpajan
Insidens tidak terpajan
Insidens 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 terpaj an
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 tidak terpajan
Insidens populasi
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 Iunexposed - Iexposed PF Iunexposed
1 - RR
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
PF
1.72 - 0.49 1.72
0.72
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 •Adjusted
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
