1 / 18

A Brief Introduction to Epidemiology - XI (Epidemiologic Research Designs: Experimental/Interventional Studies)

A Brief Introduction to Epidemiology - XI (Epidemiologic Research Designs: Experimental/Interventional Studies). Betty C. Jung, RN, MPH, CHES . Learning Objectives. To understand: What experimental studies are The value of such studies The basic methodology Pros and Cons of such studies.

albert
Download Presentation

A Brief Introduction to Epidemiology - XI (Epidemiologic Research Designs: Experimental/Interventional Studies)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. A Brief Introduction to Epidemiology - XI(Epidemiologic Research Designs:Experimental/Interventional Studies) Betty C. Jung, RN, MPH, CHES

  2. Learning Objectives • To understand: • What experimental studies are • The value of such studies • The basic methodology • Pros and Cons of such studies

  3. Introduction The primary purpose of research is to conduct a scientific, or, scholarly investigation into a phenomenon, or to answer a burning question. Research is defined as a systematic approach to problem solving.

  4. Epidemiological Study Designs • Observational Studies - examine associations between risk factors and outcomes (Analytical - determinants and risk of disease, and descriptive - patterns and frequency of disease) • Intervention Studies - explore the association between interventions and outcomes. (Experimental studies or clinical trials)

  5. Epidemiological Study Designs • Observational • Cross-Sectional • Case-control • Cohort • Interventional • Natural Experiment (Community Trial) • Field Trial • Experiment/Randomized Trails (ex. Clinical Trial)

  6. Examples of Experimental Epidemiologic Studies • Prophylactic vaccines tested on children populations to prove the efficacy of the vaccines in preventing the diseases (i.e., polio) • Prophylaxis with drugs in preventing disease (i.e., penicillin to prevent rheumatic fever) • Impact on health-related behavior and coronary heart disease in response to community-wide heart disease prevention intervention

  7. Value • Experiments are seen as the “Supreme Court” of epidemiologic research as they provide the strongest possible evidence of disease causation. • Experimental study designs can rule out with greater certainty factors that may confound potential cause and affect relationships. • A study’s degree of internal validity depends on the study design’s ability to determine whether an antecedent causes an effect (or outcome).

  8. Community Trials • Communities rather than individuals comprise the treatment groups • Appropriate for diseases that have their origins in social conditions that can be influenced by intervention directed at group behavior as well as individuals

  9. Limitations of Community Trials • Random allocation of communities is not practical • Only a small number of communities can be included • Other methods are needed to ensure any difference found can be attributed to the intervention rather than to any inherent differences between the communities studied

  10. Field Trials • Involve people who are disease-free but presumed to be at risk • Data collection – “in the field” – among non-institutionalized people in the general population • Used to evaluate interventions that reduce exposure without measuring the occurrence of health effects.

  11. Limitations of Field Trials • Hugh undertaking • Major logistic considerations • Major financial considerations • Think of how much work is required to randomize and allocate participants to various treatment groups!

  12. Experimental Study Design Time Treated - Improved Treated (T) Treated – Not Improved Sample of Cases Not Treated - Improved Not Treated (NT) (Control) Not Treated – Not Improved

  13. Randomized Trial Methodology • Random allocation - Each subject has an equal chance of being assigned to any group in the study, so that all groups in a study are similar in all characteristics not controlled by other methods, such as subject selection. • Random allocation can be used with matching to ensure the study groups are comparable

  14. Randomized Trial Design Time Improved R A N D O M I Z E D New Treatment Not Improved Defined Population Improved Current Treatment Not Improved

  15. Four Possibilities • The treatments do not differ and we correctly conclude they do not differ • The treatments do not differ but we conclude they do differ • The treatments differ but we conclude they do not differ • The treatments do differ and we correctly conclude that they do differ

  16. Pros • Helpful in assessing the value of new therapies to combat acute diseases in developing countries • Can evaluate a single variable in a precisely defined patient group • Prospective design • Eliminates bias by comparing two otherwise identical groups • Allows for meta-analysis

  17. Cons • Expensive and time consuming • Not always properly conducted – too few subjects, too short a time period • Influence of sponsorship • Use of surrogate endpoints may introduce “hidden bias” • Failure to randomize all eligible subjects • Failure to blind assessors to randomized status of subjects

  18. References • For Internet Resources on the topics covered in this lecture, check out my Web site: http://www.bettycjung.net/

More Related