Applied Epidemiology Sharla Smith

Discussion Assignments How to complete a discussion assignment –Read the chapters –Evaluate the question –Be very specific and details –Provide a reference –Spell check –Make sure your discussion is 100 words –Post by Saturday –Respond to your classmates Be detailed and present a case to support or disagree their position Respond to two classmates Use spell check

Group Assignments Check your s or announcements for group assignments Each team has been assigned a lead Contact your group If a group member doesn’t respond in 48 hours contact the professor Full credit will only be given to those who participate in the assignment

Study Designs by Validity Ranking Experimental Study- –enables us to overcome the deficiencies inherent in observational design –Uses experimentation to derive at knowledge about the causes of disease has intuitive appeal –More confidently may attribute cause and effect Prospective Cohort Study Retrospective Cohort Study Nested Case-Control Study Ecologic study Case study Anecdote

Experimental Design Steps involved in conducting an experimental study Identify and define the problem. Formulate hypotheses and deduce their consequences. Construct an experimental design that represents all the elements, conditions, and relations of the consequences. Identify and define the problem. Formulate hypotheses and deduce their consequences. Construct an experimental design that represents all the elements, conditions, and relations of the consequences. – Select sample of subjects. – Group or pair subjects. – Identify and control non experimental factors. – Select or construct, and validate instruments to measure outcomes. 5. Conduct pilot study. 6. Determine place, time, and duration of the experiment. Conduct the experiment. Compile raw data and reduce to usable form. Apply an appropriate test of significance. Conduct the experiment. Compile raw data and reduce to usable form. Apply an appropriate test of significance.

Intervention Studies Test the efficacy of a preventive or therapeutic measure Intervention Designs Include: –Controlled clinical trials (focus on the individual) –Community interventions (focus on the group or community)

Clinical Trials Outcomes: –Investigators compare rates of diseas –Death –Recovery Examples –Trials of a pharmaceutical product Cancer drugs –Product testing-cosmetics

BLINDING Single-blinded –Subjects are unaware of the group assignment –Informed content is obtained –Experimenter must treat and monitor all groups Double-Blind –Neither the subject or the participant are aware of the group assignment

Phases of a Clinical Trials Phase I Trials-safety in adult volunteers Phase II-Immunogenicity and reactogenicity in the target population Phase III-protective efficacy

Randomized The method of choice for assigning subjects to the treatment or control conditions of a clinical trial is randomized.

Cross Over Designs Any change of treatment for a patient in a clinical trial involving a switch of study treatments. Planned or unplanned Unplanned-refers to a switch of patients to different treatment conditions for various reasons.

Ethical Issues Informed consent Withholding tretment known to be effective Protecting the interest of individual patients Monitoring toxicity and side effects Deciding when to withdraw a patient

Community Trials Unlike clinical trials, these are not limited in terms of scope (representation) of their potential impact. Determine the potential benefit of new policies and programs Designed to produce changes in a target population

Measures of Effects Absolute Effects Relative Effects Statistical Measures of Effect

Absolute Effect Rate of difference or risk difference Attributable Risk May be based on: –Differences in incidence rates –Cumulative incidence –Prevalence –mortality

Significance Test Test the null hypothesis no difference Usually considered significant if pvalue is.05 or below.

Relative Effects Relative Ratio: –provides an estimate of the magnitude of association between exposure and disease –The ratio of the cumulative incidence rate in exposed to the cumulative incidence rate in the nonexposed

Q&A What’s Next? Unit 7-9