UKURAN DAMPAK DALAM EPIDEMIOLOGI

Nurul Wandasari Singgih Prodi Kesehatan Masyarakat Univ Esa Unggul 2012/2013

Measures of Public Health Impact

• Attributable Risk (AR) • Attributable Risk Percent (AR%) Number 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: association, Measure of the strength of 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 = I exposed – I nonexposed = “Risk Difference” Smoke Develop CHD

Yes No Yes No 84 87 2916 3000 4913 5000

I SM = 84 / 3000 = 0.028 = 28.0 / 1000 I NS = 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 Exposed I exposed - I unexposed 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% = (I exposed – I nonexposed ) / I exposed “Etiologic fraction” = Smoke Develop CHD

Yes No Yes No 84 87 2916 3000 4913 5000

I SM = 84 / 3000 = 0.028 = 28.0 / 1000 I NS = 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.

Incidence

Attributable Risk Percent

Exposed I exposed – I unexposed RR - 1 ------------------------------- = ------------ x 100% I exposed RR Unexposed

• 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  tidak terpajan  Insidens  populasi 

x

100 %

Population Attributable Risk Percent

PAR% = (I total – I nonexposed ) / I total Weight

Obese Slim

Diabetes

Yes No 850 250 1100 3650 5250 8900 4500 5500 10000

I T = 1100 / 10000 = 0.11 = 110 / 1000 I NE = 250 / 5500 = 0.0455 = 45.5 / 1000 (background risk) 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



I unexposed I exposed I unexposed



1 RR

PF: Vaccine efficacy

Vaccinated Unvaccinated Pop. 301,545 298,655 Total 600,200 Cases 150 515 Cases/1000 RR 0.49 0.28 1.72 Ref. 665 1.11 PF



1.72

0.49

1.72



0.72



1 0.28



0.72

Tanpa denominator

Ringkasan ukuran

Tipe Kuantitas Matematis Dengan denominator Enumerasi Hitung, angka mutlak 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 Prevalens Mortalitas Insidens Kumulatif

Incidence Density

Prevalens titik Prevalens periode

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 Fraksi Efek RD AR ER PAR AR% PAR% PF