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Causation
This document discusses association and causation in epidemiology. It defines association as the concurrence of two variables more often than expected by chance. There are different types of association, including spurious, indirect, and direct association. Causation requires considering criteria like temporality, strength of association, specificity, consistency, biological plausibility, and coherence. Together, these criteria help determine whether an observed association between factors is likely causal in nature. The goal of epidemiology is to identify potential causes of disease by studying associations between exposures and outcomes.
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Causation
- 1. Before the dawnof the 21st Century and before the advent of antibiotics , Public health since aegis has waged war against greatest threat to mankind, Plague, cholera & small pox and has won convincingly …… .
- 2. Association ,Causation Cause andeffect in Epidemiology D R D E O D AT T M S U R YAW A N S H I (MD COMMUNITY MEDICINE ,KEM,MUMBAI ) A S S I S TA N T P R O F E S S O R COMMUNITY MEDICINE DSMCH
- 3. The work ofepidemiology is related to unanswered questions ,but also unquestioned answers.
- 4. Learning Objectives Whatis Association?. Types of association. Criteria for causation. Uses of Epidemiology.
- 5. Association Find thecause of disease Hypothesis : two or more variables related /associated Proceed to measure the association between the two .
- 6. Definition of association Concurrence of two variables more often than would be expected by chance. Association does not always means casual relationship. Measure by correlation coefficient + 1 to – 1 + 1 positive correlation - 1 negative correlation
- 7. Learning Objectives Theoriesof disease causation What is cause effect ? Criteria for causal association.
- 8. Theories of causationof disease Supernatural theory – Old and medieval period Contagion theory (miasma)- Renaissance Germ theory (Koch postulates)-Early 19th century Epidemiological triad theory BEINGS model Web of causation Epidemiological wheel theory The theory of necessary and sufficient cause.
- 9. Types of association Spurious association. Indirect association. Direct association. One to one causal Multi factorial causation
- 10. Spurious association Total deliveries Died Fatalityrate Home deliveries 1000 25 2.5 % Hospital deliveries 10,000 400 4%
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- 15. Indirect association Vitamin def Seatravel Vitamin C Reddening of gums ,bleeding (Scurvy)
- 16. Direct causation : one toone causation Change in one causes change in another variable It is cause one to one causal relationship . Cause effect relation ship Factor A must be present to cause the outcome B
- 18. Multi factorial causation Multiple factors can individually cause same disease of Interest .
- 19. Multi factorial causation Highfat diet Cumulative effect of factors causing disease Lack of exercise Uncontrolled diabetes CHD
- 20. Criteria for judgingcausality Temporal association. Strength of association. Specificity of association. Consistency of association Biological plausibility Coherence of association
- 21. Criteria of causationTemporality The exposure variable should precede before the outcome. Temporal sequence is maintained.
- 22. Strength of association How much is the association : measure Relative risk & Odds ratio Dose response relationship Duration response relationship Cessation relationship.
- 23. Specificity of association 80 to 90 % of lung cancers are attributed to smoking
- 24. Consistency Studies conductedby various researchers at various times have indicated similar cause effect phenomena
- 25. Biological plausibility Isthe cause effect phenomena commensurate with already known facts Should stand to reasoning of present day knowledge.
- 26. Coherence Rise intobacco consumption has led to rise in lung cancer deaths. So when smoking and tobacco consumption was stopped ,the trend decreased.