Different Measures of Association PDF

10/15/2024 The Concept of Causality Different Measures of Association In the name of the Almighty Alipasha Meysamie, MD, MPH Professor in Community and Preventive...

10/15/2024 The Concept of Causality Different Measures of Association In the name of the Almighty Alipasha Meysamie, MD, MPH Professor in Community and Preventive Medicine Tehran University of Medical Sciences Association Measurement Students should be able to Describe the different measures for showing the Disease strength of relationships between + - T Calculate and explain different measures of association including: + – Relative Risk/Risk Ratio (RR) – Attributable Risk/Risk Difference (AR/RD) Exposure - – Attributable Risk Fraction (AF) – Population Attributable Risk (PAR) T – Population Attributable Fraction (PAF) – Odds Ratio (OR) – Leven`s Formula for PAF Calculation Association Measurement Association Measurement Disease Inc/Pre RR AR/RD AF Disease Incidence/ Relative Risk/ Attributable Risk/ Attributable + - T Prevalence Risk Ratio Risk Difference Fraction + - T a/a+b AR + a b a+b a/a+b c/c+d a/a+b-c/c+d a/a+b + a b a+b Exposure - c d c+d c/c+d Exposure - c d c+d a+ b+ a+b+c T c d +d T a+c b+d a+b+c+d 1  10/15/2024 Association Measurement Association Measurement Disease Inc/Pre RR AR/RD AF Disease Inc/Pre RR AR/RD AF Incidence/ Relative Risk/ Attributable Risk/ Attributable Incidence/ Relative Risk/ Attributable Risk/ Attributable + - T + - T Prevalence Risk Ratio Risk Difference Fraction Prevalence Risk Ratio Risk Difference Fraction a/a+b AR a/a+b AR Exposure Exposure + a b a+b a/a+b a/a+b-c/c+d + a b a+b a/a+b a/a+b-c/c+d c/c+d a/a+b c/c+d a/a+b - c d c+d c/c+d - c d c+d c/c+d T a+c b+d a+b+c+d T a+c b+d a+b+c+d Disease Inc/Pre RR AR/RD AF Disease Inc/Pre RR AR/RD AF Incidence/ Relative Risk/ Attributable Risk/ Attributable Incidence/ Relative Risk/ Attributable Risk/ Attributable + - T + - T Prevalence Risk Ratio Risk Difference Fraction Prevalence Risk Ratio Risk Difference Fraction + 30 9970 10000 30/10000 30/10000 30/10000- 24/10000 24%/30% Exposure Exposure + 30 70 100 %30 30%/6%=5 30%-6%=24% 6/10000 6/10000 30/10000 =80% - 6 9994 10000 6/10000 =5 =24/10000 =80% - 6 94 100 %6 T 36 164 20000 18/10000 T 36 164 200 %18 Association Measurement Disease In population Association Measurement PAR PAF Disease Inc/Pre RR AR/RD AF Prevalence Population Population Incidence/ Relative Risk/ Attributable Risk/ Attributable + - T + - T of exposure Attributable Attributable Prevalence Risk Ratio Risk Difference Fraction Risk Fraction a/a+b AR Exposure 𝑃𝐴𝑅 + a b a+b a/a+b a/a+b-c/c+d c/c+d a/a+b Exposure + a b a+b Pe 𝐴𝑅 ∗ 𝑃𝑒 𝐼𝑛𝑐𝑖𝑑𝑒𝑛𝑐𝑒𝑃𝑜𝑝𝑢𝑙𝑎𝑡𝑖𝑜𝑛 - c d c+d c/c+d - c d c+d T a+c b+d a+b+c+d T a+c b+d a+b+c+d Disease Inc/Pre RR AR/RD AF Disease In population Incidence/ Relative Risk/ Attributable Risk/ Attributable Prevalence PAR PAF + - T + - T Population Population Prevalence Risk Ratio Risk Difference Fraction of exposure Attributable Risk Attributable Fraction 70%/94% 24%/70% Exposure + 30 70 100 %70 70%-94%=-24% 24% ∗ 0.2 4.8% =0.75 =34% Exposure + 30 70 100 20% =4.8% 10.8% - 6 94 100 %94 - 6 94 100 𝐼𝑛𝑐𝑖𝑑𝑒𝑛𝑐𝑒𝑃𝑜𝑝𝑢𝑙𝑎𝑡𝑖𝑜𝑛 =44.44% T 36 164 200 %18 T 36 164 200 =30%*0.2+6%*0.8 =10.8% Association Measurement Disease Odds OR RR Leven`s Formula Association Measurement PAF Relative Risk/ Population + - T Odds Ratio Risk Ratio Attributable Leven`s Fraction Disease Odds OR RR Formula a/a+b 𝑎 a/b a/a+b 𝑃𝑒 𝑂𝑅 − 1 + a b a+b = PAF Exposure b/a+b 𝑏 c/d c/c+d 1 + 𝑃𝑒 𝑂𝑅 − 1 Relative Risk/ Population c/c+d 𝑐 𝑎𝑑 + - T Odds Ratio - c d c+d = = Risk Ratio Attributable d/c+d 𝑑 𝑏𝑐 Fraction T a+c b+d a+b+c+d Leven`s Disease Odds OR RR a/a+b 𝑎 a/b a/a+b 𝑃𝑒 𝑂𝑅 − 1 Formula + a b a+b = b/a+b 𝑏 c/d c/c+d 1 + 𝑃𝑒 𝑂𝑅 − 1 PAF Exposure Relative Risk/ Population + - T Odds Ratio Risk Ratio Attributable c/c+d 𝑐 𝑎𝑑 - c d c+d = = Fraction d/c+d 𝑑 𝑏𝑐 30/100 30 30/70 30% 0.2 6.71 − 1 + 30 70 100 = Exposure 70/100 70 6/94 6% 1 + 0.2 6.71 − 1 T a+c b+d a+b+c+d 6/100 6 30 ∗ 94 - 6 94 100 = = =5 =53.31% 94/100 94 70 ∗ 6 T 36 164 200 =6.71 2