Experimental epidemiological methods

Experimental epidemiological methods

1. Experimental epidemiological methods Professor Maja Miskulin, MD, PhD

2. History James Lind – 1747. one of the first noted, controlled clinical experiment in the history of medicine

3. Experimental studies confounding factors are usually not a problem in experimental studies epidemiologists usually study human populations (mainly through observational studies) experimental studies are largely used in basic medical sciences where investigators design researches on animal models

4. Experimental studies in experimental studies, the investigator has "control" over the protective factor that is being investigated the investigator determines which of the subjects will get a drug that is being investigated, and who does not the control group gets either placebo or the best existing drug on the market – so called gold standard

5. Experimental studies the best way to classify subjects in the investigated groups (exposed to investigated drug and unexposed) is randomization, which indicates the random distribution of the subjects in the groups randomization is primarily used to eliminate the effects of confounding factors

6. Experimental studies when we use experimental studies in epidemiology, we can get very strong evidence these studies should not be implemented until the probability of a causal or risk relationship has been well determined using the other types of study designs

7. Types of experimental studies randomized controlled trial (RCT) controlled field trial (CFT) community trial (CT)

8. Randomized controlled trial (RCT) the main goal of RCT is to evaluate the therapeutic approach to the patients who are included in the study individually in RCT, we can investigate the effect of drugs, surgical procedures, certain physical therapeutic methods and other therapeutic approaches

9. Controlled field trial (CFT) in CFT we want to estimate the effect of preventive intervention most commonly on healthy subjects, which are included in the study individually CFT was most frequently applied when investigating the efficacy of a vaccine

10. Controlled field trial (CFT) The Salk Polio Vaccine Field Trial - Jonas Salk administers his polio vaccine on February 26, 1957 in the Commons Room of the Cathedral of Learning at the University of Pittsburgh where the vaccine was created by Salk and his team

11. Controlled field trial (CFT) unlike RCT, CFT most commonly includes healthy subjects, and sampling is carried out from the population when investigating the efficacy and safety of the vaccine, we need to divide the healthy subjects into two groups, one that will get the active substance (exposed group) and the other who will be given placebo (unexposed group)

12. Controlled field trial (CFT) in this type of experimental study we can show results in several ways: relative risk survival curves effectiveness of the investigated vaccine (calculation of the population preventable fraction - PPF)

13. Population preventable fraction (PPF) tells us about the proportion of newly diagnosed cases of the disease that can be prevented at the population level if we apply a preventative measure in that population p – the proportion of the population that is exposed to the protective factor RR – relative risk  

14. Community trial (CT) the community trial is a type of experimental study that involves at least two whole communities, one exposed and the other unexposed some of the protective factors cannot be investigated on individuals because all inhabitants of a particular geographic area are exposed to such factors

15. Community trial (CT) i n this case, all inhabitants of a geographic area that is exposed to a protective factor are included in the study, and as a control group all inhabitants of another geographic area, where such a factor is lacking

16. Community trial (CT) o ne of the best known community trials began in 1944 in the United States, and that was a study of the effect of water fluorination on health of the teeth in children

17. N atural experiment the natural experiment is not a type of experiment studies t he term natural experiment refers to the implementation of observational epidemiological studies in case of unfortunate events, such as natural disasters (e.g. flood, fire or earthquake), or accidents caused by human error and neglect (for example, Chernobyl catastrophe and methyl-mercury poisoning in the Gulf Minamata in Japan)

18. Experimental studies ? (mark the correct answer) confounding factors are usually big problem in experimental studies WRONG confounding factors are usually not a problem in experimental studies CORRECT

19. Controlled field trial (CFT) ? (mark the correct answer) CFT was most frequently applied when investigating the efficacy of a vaccine CORRECT CFT was most frequently applied when investigating the efficacy of a surgical procedure WRONG

20. Community trial (CT) ? (mark the correct answer) the community trial is a type of analytical study that involves at least two whole communities, one exposed and the other unexposed WRONG the community trial is a type of experimental study that involves at least two whole communities, one exposed and the other unexposed CORRECT

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