HLTH 323 Lecture 12: Ch 12
12 Nov 2016
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Document Summary
In experimental studies the conditions of the study, particularly the exposure status, is directly controlled by the intervention of researchers rct and grt. Randomized controlled trials are the cornerstone for evidence based medicine because they are best in controlling bias and demonstrating cause and effect in humans. They can be characterized at preventative or therapeutic trials. Preventative trials can be further classified as primary or secondary prevention trials. Prevention trials (for individuals without the disease) used in stage of susceptibility. Intervention trials (for high risk individuals) used during the stage of presymptomatic disease and the stage of clinical disease. Therapeutic trials (patients with existing disease) used for later stages of clinical disease and stage of diminished capacity. Natural experiments are unplanned situations in nature where the levels of exposure to presumed causes differ among subgroups such that the situation resembles planned experiments (however they are observational studies).
