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Measure of Public Health Impact

Four closely related measure are used:. Attributable RiskAttributable( Risk) fractionPopulation Attributable RiskPopulation Attributable (Risk) fraction. Attributable Risk (AR). The Incidence of disease in the Exposed population whose disease can be attributed to the exposure. AR=I e ?I u.

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Measure of Public Health Impact

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    1. Measure of Public Health Impact

    2. Four closely related measure are used: Attributable Risk Attributable( Risk) fraction Population Attributable Risk Population Attributable (Risk) fraction

    3. Attributable Risk (AR) The Incidence of disease in the Exposed population whose disease can be attributed to the exposure. AR=I e I u

    4. AR= 0.018 0.003= 0.015= 1.5% The cessation of the exposure would lower the risk in the exposed group from 0.018 to 0.0030

    5. Attributable (Risk) Fraction (ARF) The proportion of disease in the exposed population whose disease can be attributed to the exposure. AR= (I e I u )/I e ARF=( RR-1)/RR The obvious advantage of the formula is that it can be used in case-control studies, in which incidence data are unavailable, but the OR can be used as an estimate of RR, if the disease is relatively rare.

    6. ARF = 0.018 0.003/ 0.018 * 100 = 83.3% RR=0.018/0.003 = 6 ARF=( RR-1)/RR * 100=(6 1)/6 *100= 83.3%

    7. ARF= percent efficacy Risk of dis. In vaccinated group= 5% Risk of dis. In the placebo group= 15% ARF=Efficacy=((15 5) / 15) * 100 = 66.7% = (3-1)/3 * 100 = 66.7 %

    8. Population Attributable Risk (PAR) The Incidence of disease in the total population whose disease can be attributed to the exposure. PAR=I p I u

    9. Population Attributable (Risk) Fraction (PARF) The proportion of disease in the total population whose disease can be attributed to the exposure. The PARF is defined as the fraction of all cases (exposed and unexposed) that would not have occurred if exposure had not occurred. PARF= (I p I u )/I p

    10. PARF= (I p I u )/I p P=exposure prevalence=0.4 q+ = 0.2 q- = 0.15 q pop = (q+ *0.4)+(q- *0.6) =0.17 PAF = (0.17 0.15) / 0.17 = 0.12 PARF=(RR-1)*P/ 1+ (RR-1)*P

    11. PAF has two Formula: 1- classic ( Levin) formula: PARF=(RR-1)*P/ 1+ (RR-1)*P P= Exposure prevalence in total population

    12. 2-Miettinen or case-based formula: PARF=[(RR-1)/RR ]* P exposure in cases

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